The scheduling server will attempt to send enough work to excede a hosts high water mark. If the amount of work the scheduling server is sending excedes four weeks, the scheduling server will not attach more work to a scheduler reply. This does not prevent the scheduling server from sending a work unit that takes more than four weeks, but merely from attaching more work after a scheduler reply has four weeks of work. If a work unit uses more disk resources than a host has available, the scheduling server will not attach that work unit. The scheduling server estimates the amount of time a work unit will take to complete with the formula (number of fpops)/(fpops per second)+(number of iops)/(iops per second). The number of fpops and number of iops are provided by the backend when creating the work unit, and the calculation speeds are included in a scheduler request. If no work is available, the scheduling server sends the message no work available with priority low, and requests that the client wait before sending another scheduler request.