diff --git a/src/od_auth.c b/src/od_auth.c
index b6adb660..0b14c367 100644
--- a/src/od_auth.c
+++ b/src/od_auth.c
@@ -10,6 +10,7 @@
 #include <stdint.h>
 #include <stdio.h>
 #include <string.h>
+#include <inttypes.h>
 #include <signal.h>
 
 #include <machinarium.h>
@@ -56,8 +57,9 @@ od_auth_frontend_cleartext(od_client_t *client)
 		return -1;
 	rc = od_write(client->io, stream);
 	if (rc == -1) {
-		od_error(&instance->log, client->io, "C (auth): write error: %s",
-		         machine_error(client->io));
+		od_error_client(&instance->log, client->id,
+		                "auth", "write error: %s",
+		                machine_error(client->io));
 		return -1;
 	}
 
@@ -66,12 +68,14 @@ od_auth_frontend_cleartext(od_client_t *client)
 		so_stream_reset(stream);
 		rc = od_read(client->io, stream, UINT32_MAX);
 		if (rc == -1) {
-			od_error(&instance->log, client->io, "C (auth): read error: %s",
-			         machine_error(client->io));
+			od_error_client(&instance->log, client->id, "auth",
+			                "read error: %s",
+			                machine_error(client->io));
 			return -1;
 		}
 		uint8_t type = *stream->s;
-		od_debug(&instance->log, client->io, "C (auth): %c", *stream->s);
+		od_debug_client(&instance->log,
+		                client->id, "auth", "%c", *stream->s);
 		/* PasswordMessage */
 		if (type == 'p')
 			break;
@@ -83,8 +87,8 @@ od_auth_frontend_cleartext(od_client_t *client)
 	rc = so_beread_password(&client_token, stream->s,
 	                        so_stream_used(stream));
 	if (rc == -1) {
-		od_error(&instance->log, client->io,
-		         "C (auth): password read error");
+		od_error_client(&instance->log, client->id, "auth",
+		                "password read error");
 		so_password_free(&client_token);
 		return -1;
 	}
@@ -99,9 +103,9 @@ od_auth_frontend_cleartext(od_client_t *client)
 	int check = so_password_compare(&client_password, &client_token);
 	so_password_free(&client_token);
 	if (! check) {
-		od_log(&instance->log, client->io,
-		       "C (auth): user '%s' incorrect password",
-		        client->startup.user);
+		od_log_client(&instance->log, client->id, "auth",
+		              "user '%s' incorrect password",
+		              client->startup.user);
 		return -1;
 	}
 	return 0;
@@ -124,8 +128,9 @@ od_auth_frontend_md5(od_client_t *client)
 		return -1;
 	rc = od_write(client->io, stream);
 	if (rc == -1) {
-		od_error(&instance->log, client->io, "C (auth): write error: %s",
-		         machine_error(client->io));
+		od_error_client(&instance->log, client->id, "auth",
+		                "write error: %s",
+		                machine_error(client->io));
 		return -1;
 	}
 
@@ -135,12 +140,14 @@ od_auth_frontend_md5(od_client_t *client)
 		so_stream_reset(stream);
 		rc = od_read(client->io, stream, UINT32_MAX);
 		if (rc == -1) {
-			od_error(&instance->log, client->io, "C (auth): read error: %s",
-			         machine_error(client->io));
+			od_error_client(&instance->log, client->id, "auth",
+			                "read error: %s",
+			                machine_error(client->io));
 			return -1;
 		}
 		uint8_t type = *stream->s;
-		od_debug(&instance->log, client->io, "C (auth): %c", *stream->s);
+		od_debug_client(&instance->log, client->id, "auth",
+		                "%c", *stream->s);
 		/* PasswordMessage */
 		if (type == 'p')
 			break;
@@ -151,8 +158,8 @@ od_auth_frontend_md5(od_client_t *client)
 	so_password_init(&client_token);
 	rc = so_beread_password(&client_token, stream->s, so_stream_used(stream));
 	if (rc == -1) {
-		od_error(&instance->log, client->io,
-		         "C (auth): password read error");
+		od_error_client(&instance->log, client->id, "auth",
+		                "password read error");
 		so_password_free(&client_token);
 		return -1;
 	}
@@ -167,7 +174,8 @@ od_auth_frontend_md5(od_client_t *client)
 	                     client->scheme->password_len,
 	                     (uint8_t*)&salt);
 	if (rc == -1) {
-		od_error(&instance->log, NULL, "memory allocation error");
+		od_error_client(&instance->log, client->id, "auth",
+		                "memory allocation error");
 		so_password_free(&client_password);
 		so_password_free(&client_token);
 		return -1;
@@ -178,9 +186,9 @@ od_auth_frontend_md5(od_client_t *client)
 	so_password_free(&client_password);
 	so_password_free(&client_token);
 	if (! check) {
-		od_log(&instance->log, client->io,
-		       "C (auth): user '%s' incorrect password",
-		        client->startup.user);
+		od_log_client(&instance->log, client->id, "auth",
+		              "user '%s' incorrect password",
+		              client->startup.user);
 		return -1;
 	}
 	return 0;
@@ -198,9 +206,9 @@ int od_auth_frontend(od_client_t *client)
 		/* try to use default user */
 		user_scheme = instance->scheme.users_default;
 		if (user_scheme == NULL) {
-			od_error(&instance->log, client->io,
-			         "C (auth): user '%s' not found",
-			         so_parameter_value(client->startup.user));
+			od_error_client(&instance->log, client->id, "auth"
+			                "user '%s' not found",
+			                so_parameter_value(client->startup.user));
 			return -1;
 		}
 	}
@@ -208,9 +216,9 @@ int od_auth_frontend(od_client_t *client)
 
 	/* is user access denied */
 	if (user_scheme->is_deny) {
-		od_log(&instance->log, client->io,
-		       "C (auth): user '%s' access denied",
-		       so_parameter_value(client->startup.user));
+		od_log_client(&instance->log, client->id, "auth",
+		              "user '%s' access denied",
+		              so_parameter_value(client->startup.user));
 		return -1;
 	}
 
@@ -242,8 +250,9 @@ int od_auth_frontend(od_client_t *client)
 		return -1;
 	rc = od_write(client->io, stream);
 	if (rc == -1) {
-		od_error(&instance->log, client->io, "C (auth): write error: %s",
-		         machine_error(client->io));
+		od_error_client(&instance->log, client->id, "auth",
+		                "write error: %s",
+		                machine_error(client->io));
 		return -1;
 	}
 	return 0;
@@ -256,14 +265,14 @@ od_auth_backend_cleartext(od_server_t *server)
 	od_route_t *route = server->route;
 	assert(route != NULL);
 
-	od_debug(&instance->log, server->io,
-	         "S (auth): requested clear-text authentication");
+	od_debug_server(&instance->log, server->id, "auth",
+	                "requested clear-text authentication");
 
 	/* validate route scheme */
 	if (route->scheme->password == NULL) {
-		od_error(&instance->log, server->io,
-		         "S (auth): password required for route '%s'",
-		          route->scheme->target);
+		od_error_server(&instance->log, server->id, "auth"
+		                "password required for route '%s'",
+		                route->scheme->target);
 		return -1;
 	}
 
@@ -275,13 +284,15 @@ od_auth_backend_cleartext(od_server_t *server)
 	                         route->scheme->password,
 	                         route->scheme->password_len + 1);
 	if (rc == -1) {
-		od_error(&instance->log, NULL, "memory allocation error");
+		od_error_server(&instance->log, server->id, "auth",
+		                "memory allocation error");
 		return -1;
 	}
 	rc = od_write(server->io, stream);
 	if (rc == -1) {
-		od_error(&instance->log, server->io, "S (auth): write error: %s",
-		         machine_error(server->io));
+		od_error_server(&instance->log, server->id, "auth",
+		                "write error: %s",
+		                machine_error(server->io));
 		return -1;
 	}
 	return 0;
@@ -294,15 +305,15 @@ od_auth_backend_md5(od_server_t *server, uint8_t salt[4])
 	od_route_t *route = server->route;
 	assert(route != NULL);
 
-	od_debug(&instance->log, server->io,
-	         "S (auth): requested md5 authentication");
+	od_debug_server(&instance->log, server->id, "auth",
+	                "requested md5 authentication");
 
 	/* validate route scheme */
 	if (route->scheme->user == NULL ||
 	    route->scheme->password == NULL) {
-		od_error(&instance->log, server->io,
-		         "S (auth): user and password required for route '%s'",
-		          route->scheme->target);
+		od_error_server(&instance->log, server->id, "auth",
+		                "user and password required for route '%s'",
+		                route->scheme->target);
 		return -1;
 	}
 
@@ -317,7 +328,8 @@ od_auth_backend_md5(od_server_t *server, uint8_t salt[4])
 	                     route->scheme->password_len,
 	                     (uint8_t*)salt);
 	if (rc == -1) {
-		od_error(&instance->log, NULL, "memory allocation error");
+		od_error_server(&instance->log, server->id, "auth",
+		                "memory allocation error");
 		so_password_free(&client_password);
 		return -1;
 	}
@@ -330,13 +342,15 @@ od_auth_backend_md5(od_server_t *server, uint8_t salt[4])
 	                         client_password.password_len);
 	so_password_free(&client_password);
 	if (rc == -1) {
-		od_error(&instance->log, NULL, "memory allocation error");
+		od_error_server(&instance->log, server->id, "auth",
+		                "memory allocation error");
 		return -1;
 	}
 	rc = od_write(server->io, stream);
 	if (rc == -1) {
-		od_error(&instance->log, server->io, "S (auth): write error: %s",
-		         machine_error(server->io));
+		od_error_server(&instance->log, server->id, "auth",
+		                "write error: %s",
+		                machine_error(server->io));
 		return -1;
 	}
 	return 0;
@@ -355,8 +369,8 @@ int od_auth_backend(od_server_t *server)
 	rc = so_feread_auth(&auth_type, salt, stream->s,
 	                    so_stream_used(stream));
 	if (rc == -1) {
-		od_error(&instance->log, server->io,
-		         "S (auth): failed to parse authentication message");
+		od_error_server(&instance->log, server->id, "auth",
+		                "failed to parse authentication message");
 		return -1;
 	}
 	switch (auth_type) {
@@ -377,8 +391,8 @@ int od_auth_backend(od_server_t *server)
 		break;
 	/* unsupported */
 	default:
-		od_error(&instance->log, server->io,
-		         "S (auth): unuspported authentication method");
+		od_error_server(&instance->log, server->id, "auth",
+		                "unsupported authentication method");
 		return -1;
 	}
 
@@ -388,32 +402,32 @@ int od_auth_backend(od_server_t *server)
 		so_stream_reset(stream);
 		rc = od_read(server->io, &server->stream, UINT32_MAX);
 		if (rc == -1) {
-			od_error(&instance->log, server->io, "S (auth): read error: %s",
-			         machine_error(server->io));
+			od_error_server(&instance->log, server->id, "auth",
+			                "read error: %s",
+			                machine_error(server->io));
 			return -1;
 		}
 		char type = *server->stream.s;
-		od_debug(&instance->log, server->io, "S (auth): %c",
-		         type);
+		od_debug_server(&instance->log, server->id, "auth",
+		                "%c", type);
 		switch (type) {
-		case 'R': {
+		case 'R':
 			rc = so_feread_auth(&auth_type, salt, stream->s,
 			                    so_stream_used(stream));
 			if (rc == -1) {
-				od_error(&instance->log, server->io,
-				         "S (auth): failed to parse authentication message");
+				od_error_server(&instance->log, server->id, "auth",
+				                "failed to parse authentication message");
 				return -1;
 			}
 			if (auth_type != 0) {
-				od_error(&instance->log, server->io,
-				        "S (auth): incorrect authentication flow");
+				od_error_server(&instance->log, server->id, "auth",
+				                "incorrect authentication flow");
 				return 0;
 			}
 			return 0;
-		}
 		case 'E':
-			od_error(&instance->log, server->io,
-			         "S (auth): authentication error");
+			od_error_server(&instance->log, server->id, "auth",
+			                "authentication error");
 			return -1;
 		}
 	}
diff --git a/src/od_backend.c b/src/od_backend.c
index 8564ce9e..648050b7 100644
--- a/src/od_backend.c
+++ b/src/od_backend.c
@@ -10,6 +10,7 @@
 #include <stdint.h>
 #include <stdio.h>
 #include <string.h>
+#include <inttypes.h>
 #include <signal.h>
 
 #include <machinarium.h>
@@ -97,8 +98,9 @@ od_backend_startup(od_server_t *server)
 		return -1;
 	rc = od_write(server->io, stream);
 	if (rc == -1) {
-		od_error(&instance->log, server->io, "S (startup): write error: %s",
-		         machine_error(server->io));
+		od_error_server(&instance->log, server->id, "startup",
+		                "write error: %s",
+		                 machine_error(server->io));
 		return -1;
 	}
 	server->count_request++;
@@ -138,14 +140,15 @@ od_backend_ready_wait(od_server_t *server, char *procedure, int time_ms)
 		rc = od_read(server->io, stream, time_ms);
 		if (rc == -1) {
 			if (! machine_timedout()) {
-				od_error(&instance->log, server->io, "S (%s): read error: %s",
-				         procedure, machine_error(server->io));
+				od_error_server(&instance->log, server->id, procedure,
+				                "read error: %s",
+				                machine_error(server->io));
 			}
 			return -1;
 		}
 		uint8_t type = stream->s[rc];
-		od_debug(&instance->log, server->io, "S (%s): %c",
-		         procedure, type);
+		od_debug_server(&instance->log, server->id, procedure,
+		                "%c", type);
 		/* ReadyForQuery */
 		if (type == 'Z') {
 			od_backend_ready(server, stream->s + rc,
@@ -166,12 +169,15 @@ od_backend_setup(od_server_t *server)
 		int rc;
 		rc = od_read(server->io, &server->stream, UINT32_MAX);
 		if (rc == -1) {
-			od_error(&instance->log, server->io, "S (setup): read error: %s",
-			         machine_error(server->io));
+			od_error_server(&instance->log, server->id, "setup",
+			                "read error: %s",
+			                machine_error(server->io));
 			return -1;
 		}
 		uint8_t type = *server->stream.s;
-		od_debug(&instance->log, server->io, "S (setup): %c", type);
+		od_debug_server(&instance->log, server->id, "setup",
+		                "%c", type);
+
 		switch (type) {
 		/* ReadyForQuery */
 		case 'Z':
@@ -188,8 +194,8 @@ od_backend_setup(od_server_t *server)
 			rc = so_feread_key(&server->key,
 			                   stream->s, so_stream_used(stream));
 			if (rc == -1) {
-				od_error(&instance->log, server->io,
-				         "S (setup): failed to parse BackendKeyData message");
+				od_error_server(&instance->log, server->id, "setup",
+				                "failed to parse BackendKeyData message");
 				return -1;
 			}
 			break;
@@ -203,8 +209,8 @@ od_backend_setup(od_server_t *server)
 		case 'E':
 			return -1;
 		default:
-			od_debug(&instance->log, server->io,
-			         "S (setup): unknown packet: %c", type);
+			od_debug_server(&instance->log, server->id, "setup",
+			                "unknown packet: %c", type);
 			return -1;
 		}
 	}
@@ -225,9 +231,10 @@ od_backend_connect(od_server_t *server)
 	int rc;
 	rc = machine_getaddrinfo(server_scheme->host, port, NULL, &ai, 0);
 	if (rc < 0) {
-		od_error(&instance->log, NULL, "failed to resolve %s:%d",
-		         server_scheme->host,
-		         server_scheme->port);
+		od_error_server(&instance->log, server->id, "connect",
+		                "failed to resolve %s:%d",
+		                server_scheme->host,
+		                server_scheme->port);
 		return -1;
 	}
 	assert(ai != NULL);
@@ -236,9 +243,10 @@ od_backend_connect(od_server_t *server)
 	rc = machine_connect(server->io, ai->ai_addr, UINT32_MAX);
 	freeaddrinfo(ai);
 	if (rc < 0) {
-		od_error(&instance->log, NULL, "failed to connect to %s:%d",
-		         server_scheme->host,
-		         server_scheme->port);
+		od_error_server(&instance->log, server->id, "connect",
+		                "failed to connect to %s:%d",
+		                server_scheme->host,
+		                server_scheme->port);
 		return -1;
 	}
 
@@ -254,7 +262,10 @@ od_backend_connect(od_server_t *server)
 	}
 #endif
 
-	od_log(&instance->log, server->io, "S: new connection");
+	od_log_server(&instance->log, server->id, NULL,
+	              "new server connection (%s:%d)",
+	              server_scheme->host,
+	              server_scheme->port);
 
 	/* startup */
 	rc = od_backend_startup(server);
@@ -294,8 +305,9 @@ od_backend_new(od_router_t *router, od_route_t *route)
 	int rc;
 	rc = machine_set_readahead(server->io, instance->scheme.readahead);
 	if (rc == -1) {
+		od_error_server(&instance->log, server->id, NULL,
+		                "failed to set readahead");
 		od_server_free(server);
-		od_error(&instance->log, NULL, "failed to set readahead");
 		return NULL;
 	}
 
@@ -332,8 +344,9 @@ od_backend_query(od_server_t *server, char *procedure, char *query, int len)
 		return -1;
 	rc = od_write(server->io, stream);
 	if (rc == -1) {
-		od_error(&instance->log, server->io, "S (%s): write error: %s",
-		         procedure, machine_error(server->io));
+		od_error_server(&instance->log, server->id, procedure,
+		                "write error: %s",
+		                machine_error(server->io));
 		return -1;
 	}
 	server->count_request++;
@@ -365,8 +378,8 @@ int od_backend_configure(od_server_t *server, so_bestartup_t *startup)
 	}
 	if (size == 0)
 		return 0;
-	od_debug(&instance->log, server->io,
-	         "S (configure): %s", query_configure);
+	od_debug_server(&instance->log, server->id, "configure",
+	                "%s", query_configure);
 	int rc;
 	rc = od_backend_query(server, "configure", query_configure,
 	                      size + 1);
@@ -380,16 +393,16 @@ int od_backend_reset(od_server_t *server)
 
 	/* server left in copy mode */
 	if (server->is_copy) {
-		od_debug(&instance->log, server->io,
-		         "S (reset): in copy, closing");
+		od_debug_server(&instance->log, server->id, "reset",
+		                "in copy, closing");
 		goto drop;
 	}
 
 	/* support route rollback off */
 	if (! route->scheme->rollback) {
 		if (server->is_transaction) {
-			od_debug(&instance->log, server->io,
-			         "S (reset): in active transaction, closing");
+			od_debug_server(&instance->log, server->id, "reset",
+			                "in active transaction, closing");
 			goto drop;
 		}
 	}
@@ -397,8 +410,8 @@ int od_backend_reset(od_server_t *server)
 	/* support route cancel off */
 	if (! route->scheme->cancel) {
 		if (! od_server_is_sync(server)) {
-			od_debug(&instance->log, server->io,
-			         "S (reset): not synchronized, closing");
+			od_debug_server(&instance->log, server->id, "reset",
+			                "not synchronized, closing");
 			goto drop;
 		}
 	}
@@ -428,10 +441,10 @@ int od_backend_reset(od_server_t *server)
 	int rc = 0;
 	for (;;) {
 		while (! od_server_is_sync(server)) {
-			od_debug(&instance->log, server->io,
-			         "S (reset): not synchronized, wait for %d msec (#%d)",
-			         wait_timeout,
-			         wait_try);
+			od_debug_server(&instance->log, server->id, "reset",
+			                "not synchronized, wait for %d msec (#%d)",
+			                wait_timeout,
+			                wait_try);
 			wait_try++;
 			rc = od_backend_ready_wait(server, "reset", wait_timeout);
 			if (rc == -1)
@@ -441,13 +454,13 @@ int od_backend_reset(od_server_t *server)
 			if (! machine_timedout())
 				goto error;
 			if (wait_try_cancel == wait_cancel_limit) {
-				od_debug(&instance->log, server->io,
-				         "S (reset): server cancel limit reached, closing");
+				od_debug_server(&instance->log, server->id, "reset",
+				                "server cancel limit reached, closing");
 				goto error;
 			}
-			od_debug(&instance->log, server->io,
-			         "S (reset): not responded, cancel (#%d)",
-			         wait_try_cancel);
+			od_debug_server(&instance->log, server->id, "reset",
+			                "not responded, cancel (#%d)",
+			                wait_try_cancel);
 			wait_try_cancel++;
 			rc = od_cancel(instance, route->scheme->server, &server->key);
 			if (rc < 0)
@@ -457,7 +470,8 @@ int od_backend_reset(od_server_t *server)
 		assert(od_server_is_sync(server));
 		break;
 	}
-	od_debug(&instance->log, server->io, "S (reset): synchronized");
+	od_debug_server(&instance->log, server->id, "reset",
+	                "synchronized");
 
 	/* send rollback in case server has an active
 	 * transaction running */
diff --git a/src/od_cancel.c b/src/od_cancel.c
index 8526a411..2a1c833c 100644
--- a/src/od_cancel.c
+++ b/src/od_cancel.c
@@ -10,6 +10,7 @@
 #include <stdint.h>
 #include <stdio.h>
 #include <string.h>
+#include <inttypes.h>
 #include <signal.h>
 
 #include <machinarium.h>
@@ -61,7 +62,7 @@ int od_cancel(od_instance_t *instance,
 	int rc;
 	rc = machine_getaddrinfo(server_scheme->host, port, NULL, &ai, 0);
 	if (rc < 0) {
-		od_error(&instance->log, NULL, "failed to resolve %s:%d",
+		od_error(&instance->log, "(cancel) failed to resolve %s:%d",
 		         server_scheme->host,
 		         server_scheme->port);
 		return -1;
@@ -74,7 +75,7 @@ int od_cancel(od_instance_t *instance,
 		machine_set_keepalive(io, 1, instance->scheme.keepalive);
 	rc = machine_set_readahead(io, instance->scheme.readahead);
 	if (rc == -1) {
-		od_error(&instance->log, NULL, "(cancel) failed to set readahead");
+		od_error(&instance->log, "(cancel) failed to set readahead");
 		return -1;
 	}
 
@@ -82,7 +83,7 @@ int od_cancel(od_instance_t *instance,
 	rc = machine_connect(io, ai->ai_addr, UINT32_MAX);
 	freeaddrinfo(ai);
 	if (rc < 0) {
-		od_error(&instance->log, NULL,
+		od_error(&instance->log,
 		         "(cancel) failed to connect to %s:%d",
 		         server_scheme->host,
 		         server_scheme->port);
@@ -100,7 +101,7 @@ int od_cancel(od_instance_t *instance,
 	if (server_scheme->tls_verify != OD_TDISABLE) {
 		tls = od_tlsbe(pooler->env, server_scheme);
 		if (tls == NULL) {
-			od_error(&pooler->od->log, NULL,
+			od_error(&pooler->od->log,
 			         "(cancel) failed to create tls context",
 			         server_scheme->host,
 			         server_scheme->port);
@@ -134,7 +135,7 @@ int od_cancel(od_instance_t *instance,
 	}
 	rc = od_write(io, &stream);
 	if (rc == -1) {
-		od_error(&instance->log, io, "(cancel): write error: %s",
+		od_error(&instance->log, "(cancel): write error: %s",
 		         machine_error(io));
 	}
 	machine_close(io);
diff --git a/src/od_client_pool.c b/src/od_client_pool.c
index 4163b8c8..945d6a75 100644
--- a/src/od_client_pool.c
+++ b/src/od_client_pool.c
@@ -10,6 +10,7 @@
 #include <stdint.h>
 #include <stdio.h>
 #include <string.h>
+#include <inttypes.h>
 #include <assert.h>
 
 #include <machinarium.h>
diff --git a/src/od_config.c b/src/od_config.c
index 7c4d3ca0..aa53c726 100644
--- a/src/od_config.c
+++ b/src/od_config.c
@@ -10,6 +10,7 @@
 #include <stdint.h>
 #include <stdio.h>
 #include <string.h>
+#include <inttypes.h>
 #include <ctype.h>
 
 #include <unistd.h>
@@ -99,28 +100,26 @@ od_config_open(od_config_t *config, char *file)
 	struct stat st;
 	int rc = lstat(file, &st);
 	if (rc == -1) {
-		od_error(config->log, NULL, "failed to open config file '%s'",
+		od_error(config->log, "failed to open config file '%s'",
 		         file);
 		return -1;
 	}
 	char *config_buf = malloc(st.st_size);
 	if (config_buf == NULL) {
-		od_error(config->log, NULL, "memory allocation error");
+		od_error(config->log, "memory allocation error");
 		return -1;
 	}
 	FILE *f = fopen(file, "r");
 	if (f == NULL) {
 		free(config_buf);
-		od_error(config->log, NULL, "failed to open config file '%s'",
-		         file);
+		od_error(config->log, "failed to open config file '%s'", file);
 		return -1;
 	}
 	rc = fread(config_buf, st.st_size, 1, f);
 	fclose(f);
 	if (rc != 1) {
 		free(config_buf);
-		od_error(config->log, NULL, "failed to open config file '%s'",
-		         file);
+		od_error(config->log, "failed to open config file '%s'", file);
 		return -1;
 	}
 	od_lex_open(&config->lex, od_config_keywords, config_buf,
@@ -146,7 +145,7 @@ od_config_error(od_config_t *config, od_token_t *tk, char *fmt, ...)
 	int line = config->lex.line;
 	if (tk)
 		line = tk->line;
-	od_error(config->log, NULL, "%s:%d %s",
+	od_error(config->log, "%s:%d %s",
 	         config->scheme->config_file, line, msg);
 }
 
diff --git a/src/od_daemon.c b/src/od_daemon.c
index 02de82d7..b026c1d0 100644
--- a/src/od_daemon.c
+++ b/src/od_daemon.c
@@ -10,6 +10,7 @@
 #include <stdint.h>
 #include <stdio.h>
 #include <string.h>
+#include <inttypes.h>
 
 #include <unistd.h>
 #include <sys/fcntl.h>
diff --git a/src/od_frontend.c b/src/od_frontend.c
index 80ba3c0c..f7966457 100644
--- a/src/od_frontend.c
+++ b/src/od_frontend.c
@@ -10,6 +10,7 @@
 #include <stdint.h>
 #include <stdio.h>
 #include <string.h>
+#include <inttypes.h>
 #include <signal.h>
 
 #include <machinarium.h>
@@ -73,8 +74,8 @@ od_frontend_startup_read(od_client_t *client)
 		if (to_read == 0)
 			break;
 		if (to_read == -1) {
-			od_error(&instance->log, client->io,
-			         "C (startup): bad startup packet");
+			od_error_client(&instance->log, client->id, "startup",
+			                "bad startup packet");
 			return -1;
 		}
 		int rc = so_stream_ensure(stream, to_read);
@@ -82,9 +83,9 @@ od_frontend_startup_read(od_client_t *client)
 			return -1;
 		rc = machine_read(client->io, (char*)stream->p, to_read, UINT32_MAX);
 		if (rc < 0) {
-			od_error(&instance->log, client->io,
-			         "C (startup): read error: %s",
-			         machine_error(client->io));
+			od_error_client(&instance->log, client->id, "startup",
+			                "read error: %s",
+			                machine_error(client->io));
 			return -1;
 		}
 		so_stream_advance(stream, to_read);
@@ -157,8 +158,9 @@ od_frontend_setup(od_client_t *client)
 		return -1;
 	rc = od_write(client->io, stream);
 	if (rc == -1) {
-		od_error(&instance->log, client->io, "C (setup): write error: %s",
-		         machine_error(client->io));
+		od_error_client(&instance->log, client->id, "setup",
+		                "write error: %s",
+		                machine_error(client->io));
 		return -1;
 	}
 	return 0;
@@ -177,8 +179,9 @@ od_frontend_ready(od_client_t *client)
 		return -1;
 	rc = od_write(client->io, stream);
 	if (rc == -1) {
-		od_error(&instance->log, client->io, "C: write error: %s",
-		         machine_error(client->io));
+		od_error_client(&instance->log, client->id,
+		                "write error: %s",
+		                machine_error(client->io));
 		return -1;
 	}
 	return 0;
@@ -214,7 +217,8 @@ od_frontend_copy_in(od_client_t *client)
 		if (rc == -1)
 			return OD_RS_ECLIENT_READ;
 		type = *stream->s;
-		od_debug(&instance->log, client->io, "C (copy): %c", *stream->s);
+		od_debug_client(&instance->log, client->id, "copy",
+		                "%c", *stream->s);
 
 		rc = od_write(server->io, stream);
 		if (rc == -1)
@@ -240,8 +244,10 @@ od_frontend_session(od_client_t *client)
 	if (status != OD_ROK)
 		return OD_RS_EPOOL;
 
-	od_server_t *server;
-	server = client->server;
+	od_server_t *server = client->server;
+	od_debug_client(&instance->log, client->id, NULL,
+	                "attached to S%" PRIu64,
+	                server->id);
 
 	/* assign client session key */
 	server->key_client = client->key;
@@ -262,7 +268,7 @@ od_frontend_session(od_client_t *client)
 			return OD_RS_ECLIENT_READ;
 		int type;
 		type = stream->s[rc];
-		od_debug(&instance->log, client->io, "C: %c", type);
+		od_debug_client(&instance->log, client->id, NULL, "%c", type);
 
 		/* client graceful shutdown */
 		if (type == 'X')
@@ -289,12 +295,13 @@ od_frontend_session(od_client_t *client)
 					return OD_RS_ESERVER_READ;
 				if (machine_connected(client->io))
 					continue;
-				od_debug(&instance->log, server->io,
-				         "S (watchdog): client disconnected");
+				od_debug_server(&instance->log, server->id, "watchdog",
+				                "client disconnected");
 				return OD_RS_ECLIENT_READ;
 			}
 			type = stream->s[rc];
-			od_debug(&instance->log, server->io, "S: %c", type);
+			od_debug_server(&instance->log, server->id, NULL,
+			                "%c", type);
 
 			/* ReadyForQuery */
 			if (type == 'Z') {
@@ -343,13 +350,18 @@ void od_frontend(void *arg)
 	od_client_t *client = arg;
 	od_instance_t *instance = client->system->instance;
 
-	od_log(&instance->log, client->io, "C: new connection");
+	char peer[128];
+	od_getpeername(client->io, peer, sizeof(peer));
+	od_log_client(&instance->log, client->id, NULL,
+	              "new client connection (%s)",
+	              peer);
 
 	/* attach client io to relay machine event loop */
 	int rc;
 	rc = machine_io_attach(client->io);
 	if (rc == -1) {
-		od_error(&instance->log, client->io, "failed to transfer client io");
+		od_error_client(&instance->log, client->id, NULL,
+		                "failed to transfer client io");
 		machine_close(client->io);
 		od_client_free(client);
 		return;
@@ -364,7 +376,8 @@ void od_frontend(void *arg)
 
 	/* client cancel request */
 	if (client->startup.is_cancel) {
-		od_debug(&instance->log, client->io, "C: cancel request");
+		od_debug_client(&instance->log, client->id, NULL,
+		                "cancel request");
 		od_router_cancel(client);
 		od_frontend_close(client);
 		return;
@@ -406,27 +419,27 @@ void od_frontend(void *arg)
 	status = od_route(client);
 	switch (status) {
 	case OD_RERROR:
-		od_error(&instance->log, client->io,
-		         "C: routing failed, closing");
+		od_error_client(&instance->log, client->id, NULL,
+		                "routing failed, closing");
 		od_frontend_close(client);
 		return;
 	case OD_RERROR_NOT_FOUND:
-		od_error(&instance->log, client->io,
-		         "C: database route '%s' is not declared, closing",
-		         so_parameter_value(client->startup.database));
+		od_error_client(&instance->log, client->id, NULL,
+		                "database route '%s' is not declared, closing",
+		                 so_parameter_value(client->startup.database));
 		od_frontend_close(client);
 		return;
 	case OD_RERROR_LIMIT:
-		od_error(&instance->log, client->io,
-		         "C: route connection limit reached, closing");
+		od_error_client(&instance->log, client->id, NULL,
+		                "route connection limit reached, closing");
 		od_frontend_close(client);
 		return;
 	case OD_ROK:;
 		od_route_t *route = client->route;
-		od_debug(&instance->log, client->io,
-		         "C: route to '%s' (using '%s' server)",
-		          route->scheme->target,
-		          route->scheme->server->name);
+		od_debug_client(&instance->log, client->id, NULL,
+		                "route to '%s' (using '%s' server)",
+		                route->scheme->target,
+		                route->scheme->server->name);
 		break;
 	}
 
@@ -445,12 +458,12 @@ void od_frontend(void *arg)
 		 * link in case of client errors and
 		 * graceful shutdown */
 		if (rc == OD_RS_OK)
-			od_log(&instance->log, client->io,
-			       "C: disconnected");
+			od_log_client(&instance->log, client->id, NULL,
+			              "disconnected");
 		else
-			od_log(&instance->log, client->io,
-			       "C: disconnected (read/write error): %s",
-			       machine_error(client->io));
+			od_log_client(&instance->log, client->id, NULL,
+			              "disconnected (read/write error): %s",
+			               machine_error(client->io));
 
 		rc = od_backend_reset(server);
 		if (rc != 1) {
@@ -462,9 +475,9 @@ void od_frontend(void *arg)
 		od_router_detach_and_unroute(client);
 		break;
 	case OD_RS_ESERVER_CONFIGURE:
-		od_log(&instance->log, server->io,
-		       "S: disconnected (server configure error): %s",
-		       machine_error(server->io));
+		od_log_server(&instance->log, server->id, NULL,
+		              "disconnected (server configure error): %s",
+		              machine_error(server->io));
 
 		/* close backend connection */
 		od_router_close_and_unroute(client);
@@ -473,9 +486,9 @@ void od_frontend(void *arg)
 	case OD_RS_ESERVER_WRITE:
 		/* close client connection and close server
 		 * connection in case of server errors */
-		od_log(&instance->log, server->io,
-		       "S: disconnected (read/write error): %s",
-		       machine_error(server->io));
+		od_log_server(&instance->log, server->id, NULL,
+		              "disconnected (read/write error): %s",
+		              machine_error(server->io));
 
 		/* close backend connection */
 		od_router_close_and_unroute(client);
diff --git a/src/od_instance.c b/src/od_instance.c
index 56a88a84..8b37bded 100644
--- a/src/od_instance.c
+++ b/src/od_instance.c
@@ -10,6 +10,7 @@
 #include <stdint.h>
 #include <stdio.h>
 #include <string.h>
+#include <inttypes.h>
 #include <signal.h>
 
 #include <machinarium.h>
@@ -67,10 +68,10 @@ void od_instance_free(od_instance_t *instance)
 static inline void
 od_usage(od_instance_t *instance, char *path)
 {
-	od_log(&instance->log, NULL, "odissey (build: %s %s)",
+	od_log(&instance->log, "odissey (build: %s %s)",
 	       OD_VERSION_GIT,
 	       OD_VERSION_BUILD);
-	od_log(&instance->log, NULL, "usage: %s <config_file>", path);
+	od_log(&instance->log, "usage: %s <config_file>", path);
 }
 
 int od_instance_main(od_instance_t *instance, int argc, char **argv)
@@ -111,7 +112,7 @@ int od_instance_main(od_instance_t *instance, int argc, char **argv)
 	if (instance->scheme.log_file) {
 		rc = od_log_open(&instance->log, instance->scheme.log_file);
 		if (rc == -1) {
-			od_error(&instance->log, NULL, "failed to open log file '%s'",
+			od_error(&instance->log, "failed to open log file '%s'",
 			         instance->scheme.log_file);
 			return 1;
 		}
@@ -122,10 +123,10 @@ int od_instance_main(od_instance_t *instance, int argc, char **argv)
 		               instance->scheme.syslog_ident,
 		               instance->scheme.syslog_facility);
 	}
-	od_log(&instance->log, NULL, "odissey (build: %s %s)",
+	od_log(&instance->log, "odissey (build: %s %s)",
 	       OD_VERSION_GIT,
 	       OD_VERSION_BUILD);
-	od_log(&instance->log, NULL, "");
+	od_log(&instance->log, "");
 	/* validate configuration scheme */
 	rc = od_scheme_validate(&instance->scheme, &instance->log);
 	if (rc == -1)
@@ -133,7 +134,7 @@ int od_instance_main(od_instance_t *instance, int argc, char **argv)
 	/* print configuration scheme */
 	if (instance->scheme.log_verbosity >= 1) {
 		od_scheme_print(&instance->scheme, &instance->log);
-		od_log(&instance->log, NULL, "");
+		od_log(&instance->log, "");
 	}
 	/* create pid file */
 	if (instance->scheme.pid_file)
@@ -152,7 +153,7 @@ int od_instance_main(od_instance_t *instance, int argc, char **argv)
 	};
 	system.task_queue = machine_queue_create();
 	if (system.task_queue == NULL) {
-		od_error(&instance->log, NULL, "failed to create task queue");
+		od_error(&instance->log, "failed to create task queue");
 		return 1;
 	}
 
diff --git a/src/od_io.c b/src/od_io.c
index cf446066..1ca541b6 100644
--- a/src/od_io.c
+++ b/src/od_io.c
@@ -10,6 +10,7 @@
 #include <stdint.h>
 #include <stdio.h>
 #include <string.h>
+#include <inttypes.h>
 
 #include <netinet/in.h>
 #include <arpa/inet.h>
diff --git a/src/od_lex.c b/src/od_lex.c
index 97145c00..d53bb41d 100644
--- a/src/od_lex.c
+++ b/src/od_lex.c
@@ -10,6 +10,7 @@
 #include <stdint.h>
 #include <stdio.h>
 #include <string.h>
+#include <inttypes.h>
 #include <ctype.h>
 
 #include "od_macro.h"
diff --git a/src/od_log.c b/src/od_log.c
index 7025e909..2fe4e451 100644
--- a/src/od_log.c
+++ b/src/od_log.c
@@ -10,6 +10,7 @@
 #include <stdint.h>
 #include <stdio.h>
 #include <string.h>
+#include <inttypes.h>
 
 #include <time.h>
 #include <unistd.h>
@@ -27,41 +28,45 @@
 #include "od_log.h"
 #include "od_io.h"
 
-int od_log_init(od_log_t *l, od_pid_t *pid, od_syslog_t *syslog)
+int od_log_init(od_log_t *log, od_pid_t *pid, od_syslog_t *syslog)
 {
-	l->verbosity = 0;
-	l->pid = pid;
-	l->syslog = syslog;
-	l->fd = 0;
+	log->verbosity = 0;
+	log->pid = pid;
+	log->syslog = syslog;
+	log->fd = 0;
 	return 0;
 }
 
-int od_log_open(od_log_t *l, char *path)
+int od_log_open(od_log_t *log, char *path)
 {
 	int rc = open(path, O_RDWR|O_CREAT|O_APPEND, 0644);
 	if (rc == -1)
 		return -1;
-	l->fd = rc;
+	log->fd = rc;
 	return 0;
 }
 
-int od_log_close(od_log_t *l)
+int od_log_close(od_log_t *log)
 {
-	if (l->fd == -1)
+	if (log->fd == -1)
 		return 0;
-	int rc = close(l->fd);
-	l->fd = -1;
+	int rc = close(log->fd);
+	log->fd = -1;
 	return rc;
 }
 
-int od_logv(od_log_t *l, od_syslogprio_t prio,
-            machine_io_t peer,
+int od_logv(od_log_t *log, od_syslogprio_t prio,
             char *ident,
+            char *object,
+            uint64_t object_id,
+            char *state,
             char *fmt, va_list args)
 {
 	char buffer[512];
+
 	/* pid */
-	int len = snprintf(buffer, sizeof(buffer), "%d ", l->pid->pid);
+	int len;
+	len = snprintf(buffer, sizeof(buffer), "%d ", log->pid->pid);
 	/* time */
 	struct timeval tv;
 	gettimeofday(&tv, NULL);
@@ -69,20 +74,27 @@ int od_logv(od_log_t *l, od_syslogprio_t prio,
 	                localtime(&tv.tv_sec));
 	len += snprintf(buffer + len, sizeof(buffer) - len, "%03d  ",
 	                (int)tv.tv_usec / 1000);
-	/* message ident */
+	/* ident */
 	if (ident)
 		len += snprintf(buffer + len, sizeof(buffer) - len, "%s ", ident);
-	/* peer */
-	if (peer) {
-		char peer_name[128];
-		od_getpeername(peer, peer_name, sizeof(peer_name));
-		len += snprintf(buffer + len, sizeof(buffer) - len, "%s ", peer_name);
+
+	/* object and id */
+	if (object) {
+		len += snprintf(buffer + len, sizeof(buffer) - len, "%s%" PRIu64": ",
+		                object, object_id);
 	}
+
+	/* state */
+	if (state) {
+		len += snprintf(buffer + len, sizeof(buffer) - len, "(%s) ", state);
+	}
+
 	/* message */
 	len += vsnprintf(buffer + len, sizeof(buffer) - len, fmt, args);
 	va_end(args);
 	len += snprintf(buffer + len, sizeof(buffer), "\n");
-	int rc = write(l->fd, buffer, len);
-	od_syslog(l->syslog, prio, buffer);
+
+	int rc = write(log->fd, buffer, len);
+	od_syslog(log->syslog, prio, buffer);
 	return rc > 0;
 }
diff --git a/src/od_log.h b/src/od_log.h
index 76eacffc..f23490ef 100644
--- a/src/od_log.h
+++ b/src/od_log.h
@@ -20,41 +20,96 @@ struct od_log
 int od_log_init(od_log_t*, od_pid_t*, od_syslog_t*);
 int od_log_open(od_log_t*, char*);
 int od_log_close(od_log_t*);
-int od_logv(od_log_t*, od_syslogprio_t, machine_io_t, char*, char*, va_list);
+int od_logv(od_log_t*, od_syslogprio_t, char*,
+            char*, uint64_t, char*,
+			char*, va_list);
 
 static inline void
-od_logset_verbosity(od_log_t *l, int level) {
-	l->verbosity = level;
+od_logset_verbosity(od_log_t *log, int level)
+{
+	log->verbosity = level;
 }
 
 static inline int
-od_log(od_log_t *l, machine_io_t peer, char *fmt, ...)
+od_log(od_log_t *log, char *fmt, ...)
 {
 	va_list args;
 	va_start(args, fmt);
-	int rc = od_logv(l, OD_SYSLOG_INFO, peer, NULL, fmt, args);
+	int rc = od_logv(log, OD_SYSLOG_INFO, NULL, NULL, 0, NULL, fmt, args);
 	va_end(args);
 	return rc;
 }
 
 static inline int
-od_debug(od_log_t *l, machine_io_t peer, char *fmt, ...)
+od_error(od_log_t *log, char *fmt, ...)
 {
-	if (l->verbosity < 2)
-		return 0;
 	va_list args;
 	va_start(args, fmt);
-	int rc = od_logv(l, OD_SYSLOG_DEBUG, peer, "debug:", fmt, args);
+	int rc = od_logv(log, OD_SYSLOG_ERROR, "error:", NULL, 0, NULL, fmt, args);
+	va_end(args);
+	return rc;
+}
+
+/* client */
+
+static inline int
+od_log_client(od_log_t *log, uint64_t id, char *state, char *fmt, ...)
+{
+	va_list args;
+	va_start(args, fmt);
+	int rc = od_logv(log, OD_SYSLOG_INFO, NULL, "C", id, state, fmt, args);
 	va_end(args);
 	return rc;
 }
 
 static inline int
-od_error(od_log_t *l, machine_io_t peer, char *fmt, ...)
+od_debug_client(od_log_t *log, uint64_t id, char *state, char *fmt, ...)
 {
 	va_list args;
 	va_start(args, fmt);
-	int rc = od_logv(l, OD_SYSLOG_ERROR, peer, "error:", fmt, args);
+	int rc = od_logv(log, OD_SYSLOG_INFO, "debug:", "C", id, state, fmt, args);
+	va_end(args);
+	return rc;
+}
+
+static inline int
+od_error_client(od_log_t *log, uint64_t id, char *state, char *fmt, ...)
+{
+	va_list args;
+	va_start(args, fmt);
+	int rc = od_logv(log, OD_SYSLOG_ERROR, "error:", "C", id, state, fmt, args);
+	va_end(args);
+	return rc;
+}
+
+/* server */
+
+static inline int
+od_log_server(od_log_t *log, uint64_t id, char *state, char *fmt, ...)
+{
+	va_list args;
+	va_start(args, fmt);
+	int rc = od_logv(log, OD_SYSLOG_INFO, NULL, "S", id, state, fmt, args);
+	va_end(args);
+	return rc;
+}
+
+static inline int
+od_debug_server(od_log_t *log, uint64_t id, char *state, char *fmt, ...)
+{
+	va_list args;
+	va_start(args, fmt);
+	int rc = od_logv(log, OD_SYSLOG_INFO, "debug:", "S", id, state, fmt, args);
+	va_end(args);
+	return rc;
+}
+
+static inline int
+od_error_server(od_log_t *log, uint64_t id, char *state, char *fmt, ...)
+{
+	va_list args;
+	va_start(args, fmt);
+	int rc = od_logv(log, OD_SYSLOG_ERROR, "error:", "S", id, state, fmt, args);
 	va_end(args);
 	return rc;
 }
diff --git a/src/od_periodic.c b/src/od_periodic.c
index 89bc68ec..e074c94b 100644
--- a/src/od_periodic.c
+++ b/src/od_periodic.c
@@ -10,6 +10,7 @@
 #include <stdint.h>
 #include <stdio.h>
 #include <string.h>
+#include <inttypes.h>
 #include <signal.h>
 
 #include <machinarium.h>
@@ -51,15 +52,15 @@ od_periodic_stats (od_router_t *router)
 	od_instance_t *instance = router->system->instance;
 	if (router->route_pool.count == 0)
 		return;
-	od_log(&instance->log, NULL, "statistics");
+	od_log(&instance->log, "statistics");
 	od_list_t *i;
 	od_list_foreach(&router->route_pool.list, i) {
 		od_route_t *route;
 		route = od_container_of(i, od_route_t, link);
-		od_log(&instance->log, NULL,
+		od_log(&instance->log,
 		       "  [%.*s, %.*s] clients %d, "
-			   "pool_active %d, "
-			   "pool_idle %d ",
+		       "pool_active %d, "
+		       "pool_idle %d ",
 		       route->id.database_len,
 		       route->id.database,
 		       route->id.user_len,
@@ -86,8 +87,9 @@ od_expire_mark(od_server_t *server, void *arg)
 	*/
 	if (! route->scheme->ttl)
 		return 0;
-	od_debug(&instance->log, server->io, "S: idle time: %d",
-	         server->idle_time);
+	od_debug_server(&instance->log, server->id, "expire",
+	                "idle time: %d",
+	                server->idle_time);
 	if (server->idle_time < route->scheme->ttl) {
 		server->idle_time++;
 		return 0;
@@ -97,7 +99,6 @@ od_expire_mark(od_server_t *server, void *arg)
 	return 0;
 }
 
-
 void od_periodic(void *arg)
 {
 	od_router_t *router = arg;
@@ -145,9 +146,9 @@ void od_periodic(void *arg)
 			server = od_routepool_next(&router->route_pool, OD_SEXPIRE);
 			if (server == NULL)
 				break;
-			od_debug(&instance->log, server->io,
-			         "S: closing idle connection (%d secs)",
-			         server->idle_time);
+			od_debug_server(&instance->log, server->id, "expire",
+			                "closing idle connection (%d secs)",
+			                server->idle_time);
 			server->idle_time = 0;
 
 			od_route_t *route = server->route;
diff --git a/src/od_pid.c b/src/od_pid.c
index e6bc189f..afa2ad7d 100644
--- a/src/od_pid.c
+++ b/src/od_pid.c
@@ -10,6 +10,7 @@
 #include <stdint.h>
 #include <stdio.h>
 #include <string.h>
+#include <inttypes.h>
 
 #include <time.h>
 #include <unistd.h>
diff --git a/src/od_pooler.c b/src/od_pooler.c
index 8a533158..04fd7f22 100644
--- a/src/od_pooler.c
+++ b/src/od_pooler.c
@@ -10,6 +10,7 @@
 #include <stdint.h>
 #include <stdio.h>
 #include <string.h>
+#include <inttypes.h>
 #include <signal.h>
 
 #include <machinarium.h>
@@ -42,6 +43,8 @@ od_pooler(void *arg)
 	od_pooler_t *pooler = arg;
 	od_instance_t *instance = pooler->system->instance;
 
+	od_log(&instance->log, "(pooler) started");
+
 	/* init pooler tls */
 	int rc;
 #if 0
@@ -77,7 +80,7 @@ od_pooler(void *arg)
 	struct addrinfo *ai = NULL;
 	rc = machine_getaddrinfo(host, port, hints_ptr, &ai, UINT32_MAX);
 	if (rc < 0) {
-		od_error(&instance->log, NULL, "failed to resolve %s:%d",
+		od_error(&instance->log, "failed to resolve %s:%d",
 		          instance->scheme.host,
 		          instance->scheme.port);
 		return;
@@ -87,7 +90,7 @@ od_pooler(void *arg)
 	/* io */
 	pooler->server = machine_io_create();
 	if (pooler->server == NULL) {
-		od_error(&instance->log, NULL, "failed to create pooler io");
+		od_error(&instance->log, "failed to create pooler io");
 		return;
 	}
 
@@ -95,16 +98,16 @@ od_pooler(void *arg)
 	rc = machine_bind(pooler->server, ai->ai_addr);
 	freeaddrinfo(ai);
 	if (rc < 0) {
-		od_error(&instance->log, NULL, "bind %s:%d failed",
+		od_error(&instance->log, "bind %s:%d failed",
 		          instance->scheme.host,
 		          instance->scheme.port);
 		return;
 	}
 
-	od_log(&instance->log, NULL, "listening on %s:%d",
+	od_log(&instance->log, "(pooler) listening on %s:%d",
 	        instance->scheme.host,
 	        instance->scheme.port);
-	od_log(&instance->log, NULL, "");
+	od_log(&instance->log, "");
 
 	/* main loop */
 	while (machine_active())
@@ -113,7 +116,7 @@ od_pooler(void *arg)
 		rc = machine_accept(pooler->server, &client_io,
 		                    instance->scheme.backlog, UINT32_MAX);
 		if (rc < 0) {
-			od_error(&instance->log, NULL, "accept failed");
+			od_error(&instance->log, "pooler accept failed");
 			continue;
 		}
 		/* todo: client_max limit */
@@ -124,7 +127,7 @@ od_pooler(void *arg)
 			machine_set_keepalive(client_io, 1, instance->scheme.keepalive);
 		rc = machine_set_readahead(client_io, instance->scheme.readahead);
 		if (rc == -1) {
-			od_error(&instance->log, NULL, "failed to set client readahead");
+			od_error(&instance->log, "failed to set client readahead");
 			machine_close(client_io);
 			machine_io_free(client_io);
 			continue;
@@ -133,8 +136,7 @@ od_pooler(void *arg)
 		/* detach io from pooler event loop */
 		rc = machine_io_detach(client_io);
 		if (rc == -1) {
-			od_error(&instance->log, client_io,
-			         "failed to transfer client io");
+			od_error(&instance->log, "failed to transfer client io");
 			machine_close(client_io);
 			machine_io_free(client_io);
 			continue;
@@ -143,8 +145,7 @@ od_pooler(void *arg)
 		/* allocate new client */
 		od_client_t *client = od_client_allocate();
 		if (client == NULL) {
-			od_error(&instance->log, client_io,
-			         "failed to allocate client object");
+			od_error(&instance->log, "failed to allocate client object");
 			machine_close(client_io);
 			machine_io_free(client_io);
 			continue;
@@ -175,7 +176,7 @@ int od_pooler_start(od_pooler_t *pooler)
 	od_instance_t *instance = pooler->system->instance;
 	pooler->machine = machine_create("pooler", od_pooler, pooler);
 	if (pooler->machine == -1) {
-		od_error(&instance->log, NULL, "failed to start server");
+		od_error(&instance->log, "failed to start server");
 		return 1;
 	}
 	return 0;
diff --git a/src/od_relay.c b/src/od_relay.c
index 56d055af..04adda70 100644
--- a/src/od_relay.c
+++ b/src/od_relay.c
@@ -10,6 +10,7 @@
 #include <stdint.h>
 #include <stdio.h>
 #include <string.h>
+#include <inttypes.h>
 #include <signal.h>
 
 #include <machinarium.h>
@@ -46,7 +47,7 @@ od_relay(void *arg)
 	od_relay_t *relay = arg;
 	od_instance_t *instance = relay->system->instance;
 
-	od_log(&instance->log, NULL, "relay: started");
+	od_log(&instance->log, "(relay) started");
 
 	for (;;)
 	{
@@ -66,7 +67,8 @@ od_relay(void *arg)
 			int64_t coroutine_id;
 			coroutine_id = machine_coroutine_create(od_frontend, client);
 			if (coroutine_id == -1) {
-				od_error(&instance->log, client->io, "failed to create coroutine");
+				od_error_client(&instance->log, client->id, "relay",
+				                "failed to create coroutine");
 				machine_close(client->io);
 				od_client_free(client);
 				break;
@@ -82,7 +84,7 @@ od_relay(void *arg)
 		machine_msg_free(msg);
 	}
 
-	od_log(&instance->log, NULL, "relay: stopped");
+	od_log(&instance->log, "(relay) stopped");
 }
 
 void od_relay_init(od_relay_t *relay, od_system_t *system)
@@ -96,7 +98,7 @@ int od_relay_start(od_relay_t *relay)
 	od_instance_t *instance = relay->system->instance;
 	relay->machine = machine_create("relay", od_relay, relay);
 	if (relay->machine == -1) {
-		od_error(&instance->log, NULL, "failed to start relay");
+		od_error(&instance->log, "failed to start relay");
 		return 1;
 	}
 	return 0;
diff --git a/src/od_route_pool.c b/src/od_route_pool.c
index d170c3be..2d627a91 100644
--- a/src/od_route_pool.c
+++ b/src/od_route_pool.c
@@ -10,6 +10,7 @@
 #include <stdint.h>
 #include <stdio.h>
 #include <string.h>
+#include <inttypes.h>
 #include <assert.h>
 
 #include <machinarium.h>
diff --git a/src/od_router.c b/src/od_router.c
index 68552a5b..3338fd81 100644
--- a/src/od_router.c
+++ b/src/od_router.c
@@ -10,6 +10,7 @@
 #include <stdint.h>
 #include <stdio.h>
 #include <string.h>
+#include <inttypes.h>
 #include <signal.h>
 
 #include <machinarium.h>
@@ -96,7 +97,7 @@ od_router_fwd(od_router_t *router, so_bestartup_t *startup)
 		return route;
 	route = od_routepool_new(&router->route_pool, route_scheme, &id);
 	if (route == NULL) {
-		od_error(&instance->log, NULL, "failed to allocate route");
+		od_error(&instance->log, "failed to allocate route");
 		return NULL;
 	}
 	return route;
@@ -124,13 +125,17 @@ od_router_attacher(void *arg)
 
 	/* TODO: wait */
 
+	od_router_t *router;
+	router = client->system->router;
+
 	/* create new backend connection */
-	server = od_backend_new(client->system->router, route);
+	server = od_backend_new(router, route);
 	if (server == NULL) {
 		msg_attach->status = OD_RERROR;
 		machine_queue_put(msg_attach->response, msg);
 		return;
 	}
+	server->id = router->server_seq++;
 
 	/* detach server io from router context */
 	machine_io_detach(server->io);
@@ -150,14 +155,13 @@ od_router(void *arg)
 	od_router_t *router = arg;
 	od_instance_t *instance = router->system->instance;
 
-	od_log(&instance->log, NULL, "router: started");
+	od_log(&instance->log, "(router) started");
 
 	/* start periodic task coroutine */
 	int64_t coroutine_id;
 	coroutine_id = machine_coroutine_create(od_periodic, router);
 	if (coroutine_id == -1) {
-		od_error(&instance->log, NULL,
-		         "failed to create periodic coroutine");
+		od_error(&instance->log, "failed to create periodic coroutine");
 		return;
 	}
 
@@ -189,8 +193,8 @@ od_router(void *arg)
 			int client_total;
 			client_total = od_clientpool_total(&route->client_pool);
 			if (client_total >= route->scheme->client_max) {
-				od_log(&instance->log, NULL,
-				       "router: route '%s' client_max reached (%d)",
+				od_log(&instance->log,
+				       "(router) route '%s' client_max reached (%d)",
 				       route->scheme->target,
 				       route->scheme->client_max);
 				msg_route->status = OD_RERROR_LIMIT;
@@ -319,9 +323,10 @@ int od_router_init(od_router_t *router, od_system_t *system)
 	od_routepool_init(&router->route_pool);
 	router->machine = -1;
 	router->system = system;
+	router->server_seq = 0;
 	router->queue = machine_queue_create();
 	if (router->queue == NULL) {
-		od_error(&instance->log, NULL, "failed to create router queue");
+		od_error(&instance->log, "failed to create router queue");
 		return -1;
 	}
 	return 0;
@@ -332,7 +337,7 @@ int od_router_start(od_router_t *router)
 	od_instance_t *instance = router->system->instance;
 	router->machine = machine_create("router", od_router, router);
 	if (router->machine == -1) {
-		od_error(&instance->log, NULL, "failed to start router");
+		od_error(&instance->log, "failed to start router");
 		return 1;
 	}
 	return 0;
diff --git a/src/od_router.h b/src/od_router.h
index f853982e..5cc9f30a 100644
--- a/src/od_router.h
+++ b/src/od_router.h
@@ -22,6 +22,7 @@ struct od_router
 	int64_t         machine;
 	od_routepool_t  route_pool;
 	machine_queue_t queue;
+	uint64_t        server_seq;
 	od_system_t    *system;
 };
 
diff --git a/src/od_scheme.c b/src/od_scheme.c
index 059ed9b5..e1b97d0c 100644
--- a/src/od_scheme.c
+++ b/src/od_scheme.c
@@ -9,6 +9,7 @@
 #include <stdarg.h>
 #include <stdio.h>
 #include <string.h>
+#include <inttypes.h>
 
 #include <machinarium.h>
 
@@ -178,7 +179,7 @@ int od_scheme_validate(od_scheme_t *scheme, od_log_t *log)
 {
 	/* pooling mode */
 	if (scheme->pooling == NULL) {
-		od_error(log, NULL, "pooling mode is not set");
+		od_error(log, "pooling mode is not set");
 		return -1;
 	}
 	if (strcmp(scheme->pooling, "session") == 0)
@@ -188,20 +189,20 @@ int od_scheme_validate(od_scheme_t *scheme, od_log_t *log)
 		scheme->pooling_mode = OD_PTRANSACTION;
 
 	if (scheme->pooling_mode == OD_PUNDEF) {
-		od_error(log, NULL, "unknown pooling mode");
+		od_error(log, "unknown pooling mode");
 		return -1;
 	}
 
 	/* routing mode */
 	if (scheme->routing == NULL) {
-		od_error(log, NULL, "routing mode is not set");
+		od_error(log, "routing mode is not set");
 		return -1;
 	}
 	if (strcmp(scheme->routing, "forward") == 0)
 		scheme->routing_mode = OD_RFORWARD;
 
 	if (scheme->routing_mode == OD_RUNDEF) {
-		od_error(log, NULL, "unknown routing mode");
+		od_error(log, "unknown routing mode");
 		return -1;
 	}
 
@@ -226,14 +227,14 @@ int od_scheme_validate(od_scheme_t *scheme, od_log_t *log)
 		if (strcmp(scheme->tls_mode, "verify_full") == 0) {
 			scheme->tls_verify = OD_TVERIFY_FULL;
 		} else {
-			od_error(log, NULL, "unknown tls mode");
+			od_error(log, "unknown tls mode");
 			return -1;
 		}
 	}
 
 	/* servers */
 	if (od_list_empty(&scheme->servers)) {
-		od_error(log, NULL, "no servers defined");
+		od_error(log, "no servers defined");
 		return -1;
 	}
 	od_list_t *i;
@@ -241,7 +242,7 @@ int od_scheme_validate(od_scheme_t *scheme, od_log_t *log)
 		od_schemeserver_t *server;
 		server = od_container_of(i, od_schemeserver_t, link);
 		if (server->host == NULL) {
-			od_error(log, NULL, "server '%s': no host is specified",
+			od_error(log, "server '%s': no host is specified",
 			         server->name);
 			return -1;
 		}
@@ -261,7 +262,7 @@ int od_scheme_validate(od_scheme_t *scheme, od_log_t *log)
 			if (strcmp(server->tls_mode, "verify_full") == 0) {
 				server->tls_verify = OD_TVERIFY_FULL;
 			} else {
-				od_error(log, NULL, "unknown server tls mode");
+				od_error(log, "unknown server tls mode");
 				return -1;
 			}
 		}
@@ -274,19 +275,19 @@ int od_scheme_validate(od_scheme_t *scheme, od_log_t *log)
 		od_schemeroute_t *route;
 		route = od_container_of(i, od_schemeroute_t, link);
 		if (route->route == NULL) {
-			od_error(log, NULL, "route '%s': no route server is specified",
+			od_error(log, "route '%s': no route server is specified",
 			         route->target);
 			return -1;
 		}
 		route->server = od_schemeserver_match(scheme, route->route);
 		if (route->server == NULL) {
-			od_error(log, NULL, "route '%s': no route server '%s' found",
+			od_error(log, "route '%s': no route server '%s' found",
 			         route->target);
 			return -1;
 		}
 		if (route->is_default) {
 			if (default_route) {
-				od_error(log, NULL, "more than one default route");
+				od_error(log, "more than one default route");
 				return -1;
 			}
 			default_route = route;
@@ -296,7 +297,7 @@ int od_scheme_validate(od_scheme_t *scheme, od_log_t *log)
 
 	/* users */
 	if (od_list_empty(&scheme->users)) {
-		od_error(log, NULL, "no users defined");
+		od_error(log, "no users defined");
 		return -1;
 	}
 
@@ -307,9 +308,9 @@ int od_scheme_validate(od_scheme_t *scheme, od_log_t *log)
 		user = od_container_of(i, od_schemeuser_t, link);
 		if (! user->auth) {
 			if (user->is_default)
-				od_error(log, NULL, "default user authentication mode is not defined");
+				od_error(log, "default user authentication mode is not defined");
 			 else
-				od_error(log, NULL, "user '%s' authentication mode is not defined",
+				od_error(log, "user '%s' authentication mode is not defined",
 				         user->user);
 			return -1;
 		}
@@ -319,7 +320,7 @@ int od_scheme_validate(od_scheme_t *scheme, od_log_t *log)
 		if (strcmp(user->auth, "clear_text") == 0) {
 			user->auth_mode = OD_ACLEAR_TEXT;
 			if (user->password == NULL) {
-				od_error(log, NULL, "user '%s' password is not set",
+				od_error(log, "user '%s' password is not set",
 				         user->user);
 				return -1;
 			}
@@ -327,18 +328,18 @@ int od_scheme_validate(od_scheme_t *scheme, od_log_t *log)
 		if (strcmp(user->auth, "md5") == 0) {
 			user->auth_mode = OD_AMD5;
 			if (user->password == NULL) {
-				od_error(log, NULL, "user '%s' password is not set",
+				od_error(log, "user '%s' password is not set",
 				         user->user);
 				return -1;
 			}
 		} else {
-			od_error(log, NULL, "user '%s' has unknown authentication mode",
+			od_error(log, "user '%s' has unknown authentication mode",
 			         user->user);
 			return -1;
 		}
 		if (user->is_default) {
 			if (default_user) {
-				od_error(log, NULL, "more than one default user");
+				od_error(log, "more than one default user");
 				return -1;
 			}
 			default_user = user;
@@ -350,102 +351,102 @@ int od_scheme_validate(od_scheme_t *scheme, od_log_t *log)
 
 void od_scheme_print(od_scheme_t *scheme, od_log_t *log)
 {
-	od_log(log, NULL, "using configuration file '%s'",
+	od_log(log, "using configuration file '%s'",
 	       scheme->config_file);
 	if (scheme->log_verbosity)
-		od_log(log, NULL, "log_verbosity %d", scheme->log_verbosity);
+		od_log(log, "log_verbosity %d", scheme->log_verbosity);
 	if (scheme->log_file)
-		od_log(log, NULL, "log_file %s", scheme->log_file);
+		od_log(log, "log_file %s", scheme->log_file);
 	if (scheme->pid_file)
-		od_log(log, NULL, "pid_file %s", scheme->pid_file);
+		od_log(log, "pid_file %s", scheme->pid_file);
 	if (scheme->syslog)
-		od_log(log, NULL, "syslog %d", scheme->syslog);
+		od_log(log, "syslog %d", scheme->syslog);
 	if (scheme->syslog_ident)
-		od_log(log, NULL, "syslog_ident %s", scheme->syslog_ident);
+		od_log(log, "syslog_ident %s", scheme->syslog_ident);
 	if (scheme->syslog_facility)
-		od_log(log, NULL, "syslog_facility %s", scheme->syslog_facility);
+		od_log(log, "syslog_facility %s", scheme->syslog_facility);
 	if (scheme->stats_period)
-		od_log(log, NULL, "stats_period %d", scheme->stats_period);
+		od_log(log, "stats_period %d", scheme->stats_period);
 	if (scheme->daemonize)
-		od_log(log, NULL, "daemonize %s",
+		od_log(log, "daemonize %s",
 		       scheme->daemonize ? "yes" : "no");
-	od_log(log, NULL, "");
-	od_log(log, NULL, "pooling %s", scheme->pooling);
-	od_log(log, NULL, "");
-	od_log(log, NULL, "listen");
-	od_log(log, NULL, "  host            %s ", scheme->host);
-	od_log(log, NULL, "  port            %d", scheme->port);
-	od_log(log, NULL, "  backlog         %d", scheme->backlog);
-	od_log(log, NULL, "  nodelay         %d", scheme->nodelay);
-	od_log(log, NULL, "  keepalive       %d", scheme->keepalive);
-	od_log(log, NULL, "  readahead       %d", scheme->readahead);
+	od_log(log, "");
+	od_log(log, "pooling %s", scheme->pooling);
+	od_log(log, "");
+	od_log(log, "listen");
+	od_log(log, "  host            %s ", scheme->host);
+	od_log(log, "  port            %d", scheme->port);
+	od_log(log, "  backlog         %d", scheme->backlog);
+	od_log(log, "  nodelay         %d", scheme->nodelay);
+	od_log(log, "  keepalive       %d", scheme->keepalive);
+	od_log(log, "  readahead       %d", scheme->readahead);
 	if (scheme->tls_mode)
-	od_log(log, NULL, "  tls_mode        %s", scheme->tls_mode);
+	od_log(log, "  tls_mode        %s", scheme->tls_mode);
 	if (scheme->tls_ca_file)
-	od_log(log, NULL, "  tls_ca_file     %s", scheme->tls_ca_file);
+	od_log(log, "  tls_ca_file     %s", scheme->tls_ca_file);
 	if (scheme->tls_key_file)
-	od_log(log, NULL, "  tls_key_file    %s", scheme->tls_key_file);
+	od_log(log, "  tls_key_file    %s", scheme->tls_key_file);
 	if (scheme->tls_cert_file)
-	od_log(log, NULL, "  tls_cert_file   %s", scheme->tls_cert_file);
+	od_log(log, "  tls_cert_file   %s", scheme->tls_cert_file);
 	if (scheme->tls_protocols)
-	od_log(log, NULL, "  tls_protocols   %s", scheme->tls_protocols);
-	od_log(log, NULL, "");
-	od_log(log, NULL, "servers");
+	od_log(log, "  tls_protocols   %s", scheme->tls_protocols);
+	od_log(log, "");
+	od_log(log, "servers");
 	od_list_t *i;
 	od_list_foreach(&scheme->servers, i) {
 		od_schemeserver_t *server;
 		server = od_container_of(i, od_schemeserver_t, link);
-		od_log(log, NULL, "  <%s> %s",
+		od_log(log, "  <%s> %s",
 		       server->name ? server->name : "",
 		       server->is_default ? "default" : "");
-		od_log(log, NULL, "    host          %s", server->host);
-		od_log(log, NULL, "    port          %d", server->port);
+		od_log(log, "    host          %s", server->host);
+		od_log(log, "    port          %d", server->port);
 		if (server->tls_mode)
-		od_log(log, NULL, "    tls_mode      %s", server->tls_mode);
+		od_log(log, "    tls_mode      %s", server->tls_mode);
 		if (server->tls_ca_file)
-		od_log(log, NULL, "    tls_ca_file   %s", server->tls_ca_file);
+		od_log(log, "    tls_ca_file   %s", server->tls_ca_file);
 		if (server->tls_key_file)
-		od_log(log, NULL, "    tls_key_file  %s", server->tls_key_file);
+		od_log(log, "    tls_key_file  %s", server->tls_key_file);
 		if (server->tls_cert_file)
-		od_log(log, NULL, "    tls_cert_file %s", server->tls_cert_file);
+		od_log(log, "    tls_cert_file %s", server->tls_cert_file);
 		if (server->tls_protocols)
-		od_log(log, NULL, "    tls_protocols %s", server->tls_protocols);
+		od_log(log, "    tls_protocols %s", server->tls_protocols);
 	}
-	od_log(log, NULL, "");
-	od_log(log, NULL, "routing");
-	od_log(log, NULL, "  mode %s", scheme->routing);
+	od_log(log, "");
+	od_log(log, "routing");
+	od_log(log, "  mode %s", scheme->routing);
 	od_list_foreach(&scheme->routing_table, i) {
 		od_schemeroute_t *route;
 		route = od_container_of(i, od_schemeroute_t, link);
-		od_log(log, NULL, "  <%s>", route->target);
-		od_log(log, NULL, "    server        %s", route->route);
+		od_log(log, "  <%s>", route->target);
+		od_log(log, "    server        %s", route->route);
 		if (route->database)
-		od_log(log, NULL, "    database      %s", route->database);
+		od_log(log, "    database      %s", route->database);
 		if (route->user)
-		od_log(log, NULL, "    user          %s", route->user);
-		od_log(log, NULL, "    ttl           %d", route->ttl);
-		od_log(log, NULL, "    cancel        %s",
+		od_log(log, "    user          %s", route->user);
+		od_log(log, "    ttl           %d", route->ttl);
+		od_log(log, "    cancel        %s",
 		       route->discard ? "yes" : "no");
-		od_log(log, NULL, "    rollback      %s",
+		od_log(log, "    rollback      %s",
 			   route->discard ? "yes" : "no");
-		od_log(log, NULL, "    discard       %s",
+		od_log(log, "    discard       %s",
 		       route->discard ? "yes" : "no");
-		od_log(log, NULL, "    pool_size     %d", route->pool_size);
-		od_log(log, NULL, "    pool_timeout  %d", route->pool_timeout);
+		od_log(log, "    pool_size     %d", route->pool_size);
+		od_log(log, "    pool_timeout  %d", route->pool_timeout);
 	}
 	if (! od_list_empty(&scheme->users)) {
-		od_log(log, NULL, "");
-		od_log(log, NULL, "users");
+		od_log(log, "");
+		od_log(log, "users");
 		od_list_foreach(&scheme->users, i) {
 			od_schemeuser_t *user;
 			user = od_container_of(i, od_schemeuser_t, link);
 			if (user->is_default)
-				od_log(log, NULL, "  default");
+				od_log(log, "  default");
 			else
-				od_log(log, NULL, "  <%s>", user->user);
+				od_log(log, "  <%s>", user->user);
 			if (user->is_deny)
-				od_log(log, NULL, "    deny");
-			od_log(log, NULL, "    authentication %s", user->auth);
+				od_log(log, "    deny");
+			od_log(log, "    authentication %s", user->auth);
 		}
 	}
 }
diff --git a/src/od_server.h b/src/od_server.h
index b90f2137..29b33b1e 100644
--- a/src/od_server.h
+++ b/src/od_server.h
@@ -20,6 +20,7 @@ typedef enum
 struct od_server
 {
 	od_serverstate_t  state;
+	uint64_t          id;
 	so_stream_t       stream;
 	machine_io_t      io;
 	machine_tls_t     tls;
@@ -44,6 +45,7 @@ static inline void
 od_server_init(od_server_t *server)
 {
 	server->state          = OD_SUNDEF;
+	server->id             = 0;
 	server->route          = NULL;
 	server->system         = NULL;
 	server->io             = NULL;
diff --git a/src/od_server_pool.c b/src/od_server_pool.c
index 4a0a3bcb..a8894e07 100644
--- a/src/od_server_pool.c
+++ b/src/od_server_pool.c
@@ -10,6 +10,7 @@
 #include <stdint.h>
 #include <stdio.h>
 #include <string.h>
+#include <inttypes.h>
 #include <assert.h>
 
 #include <machinarium.h>
diff --git a/src/od_syslog.c b/src/od_syslog.c
index aff13af4..ab939777 100644
--- a/src/od_syslog.c
+++ b/src/od_syslog.c
@@ -10,6 +10,7 @@
 #include <stdint.h>
 #include <stdio.h>
 #include <string.h>
+#include <inttypes.h>
 
 #include <syslog.h>