On 25 Mar 2015, at 12:45am, Keith Medcalf <kmedcalf at dessus.com> wrote:
> I don't know what sort of device cache your devices have, or whether it is > volatile or not. You would have to check with the manufacturer to see how > these settings (assuming they are available) affect the actual writing to the > non-volatile storage. Those Samsung SSD devices have a small volatile on-board cache. SSDs are arranged in a complicated way and writing one block sometimes involved more than one operation. Because of this the amount of time a write takes varies considerably. If power to the box is lost it might or might not be able to commit that cache to the real non-volatile storage before the SSD itself loses power. No way to tell. Your detailed description of the options available in devmgmt.msc (thank you for the education) makes me even more convinced that the OP's System 1 was lying to him about supporting in-order writes. Unfortunately, although tests for in-order writes exist for single drives it's not possible to test a mirroring RAID for the same thing unless you can get at the internals of the RAID firmware. But I like your suggestion of intentionally turning off ACID features to test the speed. Simon.
