WR aside size versus prefetch disable size

Prefetch is a read cache feature that reads blocks ahead of a set of previous reads in order to accelerate sequential read operations. Prefetch settings affect how the array detects sequential reads that would benefit from prefetch, and how close the reads need to be to each other on the disk for prefetching to continue once it starts.

Write Aside affects whether writes are cached or sent straight to the disks. If the write IO size is equal or larger than the Write Aside setting, the IO bypasses write cache as it’s written to the disk. This can relieve write cache pressure for high bandwidth writes, typically associated with sequential writes.

Richard J Anderson