Flushing cache memory of dirty metadata in a plurality of file systems without either letting the caches reach their maximum capacity, or using so much of the total system IO process bandwidth that host system IO process requests are unreasonably delayed, may include determining the length of an interval between sync operations for each individual one of the plurality of file system, and how to divide a system wide maximum sync process IO operation bandwidth fairly between various ones of the plurality of file systems. A computer dynamically measures overall system operation rates, and calculates an available portion of a current calculated sync operation bandwidth for each file system. The computer also measures file system operation rates and determines how long a time period should be between sync operations in each file system.