WT caching negatively affects the array’s performance under linear workload. The speed loss amounts to 125%! However, the difference between the two caching modes becomes smaller as the request queue is getting longer. At request queue = 256, WT caching is even preferable, bringing about a 10% performance gain.

Switching from WB to WT caching, we see the same effect as with the RAID0 array, but the value of the loss is smaller (244%).

So WT caching very negatively affects performance of RAID0 and RAID10 arrays. You’ve got choice to make: between the high speed of WriteBack and the high reliability of WriteThrough. For the RAID5, the speed depends on the type of caching only under small workloads. This dependency diminishes suddenly under heavier loads, so you should enable WriteThrough for your RAID5.