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. -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
