Hi.
How would BBU cache help you if it lies about fsync? I suppose any RAID controller removes data from BBU cache after it was fsynced by the drive. As I know, there is no other "magic command" for drive to tell controller that the data is safe now and can be removed from BBU cache.
Вт, 7 лип. 2015 11:59 Graeme B. Bell <graeme.bell@xxxxxxxx> пише:
Yikes. I would not be able to sleep tonight if it were not for the BBU cache in front of these disks...
diskchecker.pl consistently reported several examples of corruption post-power-loss (usually 10 - 30 ) on unprotected M500s/M550s, so I think it's pretty much open to debate what types of madness and corruption you'll find if you look close enough.
G
On 07 Jul 2015, at 16:59, Heikki Linnakangas <hlinnaka@xxxxxx> wrote:
>
> So it lies about fsync()... The next question is, does it nevertheless enforce the correct ordering of persisting fsync'd data? If you write to file A and fsync it, then write to another file B and fsync it too, is it guaranteed that if B is persisted, A is as well? Because if it isn't, you can end up with filesystem (or database) corruption anyway.
>
> - Heikki
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