PERC 9 has a virtual disk setting for "disk cache policy". The help in OpenManage says it's disabled by default for SAS but with the latest OpenManage I find it's enabled.
Previous posts have described this setting as applying to write caching not read caching. Previous posts have discouraged turning it on because of what would happen if power failed to the drive and cache contents were not written to disk. Seems reasonable.
BUT now Seagate and HGST have things like 'Turbo Boost' and "NVC Quick Cache" that are non-volatile approaches to write caching.
So I'm wondering if the best practice to this setting:
1.) Depends on the way caching is implemented in the drive. If it's volatile caution is warranted concerning how much faith you have in your UPS.
2.) For any SAS drives shipped recently just turn it on?