I have moved the data directory (xlog, base, global, and everything) to an ext4 file system. The result hasn't changed unfortuately. With the same load test the average response time: 80ms; from 40ms to 120 ms everything occurs.
This ext4 has default settings in fstab.
Have you got any other idea what is going on here?
Thanks,
Otto
2011/12/8 Marti Raudsepp
<marti@juffo.org>On Thu, Dec 8, 2011 at 06:37, Aidan Van Dyk <
aidan@highrise.ca> wrote:
> Let me guess, debian squeeze, with data and xlog on both on a single
> ext3 filesystem, and the fsync done by your commit (xlog) is flushing
> all the dirty data of the entire filesystem (including PG data writes)
> out before it can return...
(If it's the root file system, you need to add
rootfsflags=data=writeback to your kernel boot flags)
While this setting is safe and recommended for PostgreSQL and other
transactional databases, it can cause garbage to appear in recently
written files after a crash/power loss -- for applications that don't
correctly fsync data to disk.
Regards,
Marti