On 28/01/2021 10:02, Andrei Borzenkov wrote:
On Thu, Jan 28, 2021 at 10:40 AM Per Jessen <per@computer.org> wrote:
The built-in cache on the disk drive is for speeding up reads, not writes.
And begs the question about who backs up the hard disk buffer memory.
It is not used for write caching.
It is. Unless HDD has internal non-volatile backup (some have) it should really be disabled, and this is normally default when used with RAID controllers - except some vendors lie and retain write cache. Good for benchmarks ...
Yeah, you're right, I know there is a setting to enable it. We check every new drive when they are installed, just in case - we have not seen any IBM/Hitachi/Seagate/WDC drive with write cache enabled in at least 10 years. I don't know if we ever have, but we don't keep the test records for longer than that. -- Per Jessen, Herrliberg (2.6°C)