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.b...@nibio.no> 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 <hlinn...@iki.fi> 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 > > > > -- > Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org) > To make changes to your subscription: > http://www.postgresql.org/mailpref/pgsql-performance >
