On Sat, Jun 5, 2010 at 5:03 PM, Jon Schewe <jpschewe@xxxxxxx> wrote: > > > On 06/05/2010 05:52 PM, Greg Smith wrote: >> Jon Schewe wrote: >>>> If that's the case, what you've measured is which filesystems are >>>> safe because they default to flushing drive cache (the ones that take >>>> around 15 minutes) and which do not (the ones that take >=around 2 >>>> hours). You can't make ext3 flush the cache correctly no matter what >>>> you do with barriers, they just don't work on ext3 the way PostgreSQL >>>> needs them to. >>>> >>>> >>> So the 15 minute runs are doing it correctly and safely, but the slow >>> ones are doing the wrong thing? That would imply that ext3 is the safe >>> one. But your last statement suggests that ext3 is doing the wrong >>> thing. >>> >> >> I goofed and reversed the two times when writing that. As is always >> the case with this sort of thing, the unsafe runs are the fast ones. >> ext3 does not ever do the right thing no matter how you configure it, >> you have to compensate for its limitations with correct hardware setup >> to make database writes reliable. >> > OK, so if I want the 15 minute speed, I need to give up safety (OK in > this case as this is just research testing), or see if I can tune > postgres better. Or use a trustworthy hardware caching battery backed RAID controller, either in RAID mode or JBOD mode. -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
