It is more complicated with the RAID5 array. Disabling write-caching at low loads leads to a performance hit. At high loads, on the contrary, you may have a speed gain by turning it off. Keep it in mind, however, that the maximum speed loss from disabled caching is 165%, while the maximum speed gain is only 15%.

We will not venture a guess as to why the RAID5 array may be slower with enabled lazy writing.

The speed of the RAID10 array is always decreasing if you disable caching and as lower as there is a higher percentage of write requests.

So we can say that the WriteBack caching policy greatly improves the speed of processing write requests (once again, you must insert the battery into the controller to enable this mode). The only exception is the RAID5 array at very high loads, which are virtually impossible in practice.