On Jul 9, 2009, at 3:53 AM, Yaroslav Tykhiy wrote:
On 08/07/2009, at 8:39 PM, Alban Hertroys wrote:
On Jul 8, 2009, at 2:50 AM, Yaroslav Tykhiy wrote:
IIRC prefetch tries to keep data (disk blocks?) in memory that it
fetched recently.
What you described is just a disk cache. And a
Alban Hertroys wrote:
I don't know how you partitioned your zpools, but to me it seems like
it'd be preferable to have the PostgreSQL tablespaces (and possibly
other data that's likely to be accessed randomly) in a separate zpool
from the rest of the system so you can restrict disabling
On Jul 8, 2009, at 2:50 AM, Yaroslav Tykhiy wrote:
Hi All,
I have a mid-size database (~300G) used as an email store and
running on a FreeBSD + ZFS combo. Its PG_DATA is on ZFS whilst xlog
goes to a different FFS disk. ZFS prefetch was enabled by default
and disk time on PG_DATA was
On 08/07/2009, at 8:39 PM, Alban Hertroys wrote:
On Jul 8, 2009, at 2:50 AM, Yaroslav Tykhiy wrote:
Hi All,
I have a mid-size database (~300G) used as an email store and
running on a FreeBSD + ZFS combo. Its PG_DATA is on ZFS whilst
xlog goes to a different FFS disk. ZFS prefetch was
On Wed, Jul 8, 2009 at 7:53 PM, Yaroslav Tykhiyy...@barnet.com.au wrote:
Are you a local FreeBSD expert? ;-) Jokes apart, I don't think this topic
has to do with FreeBSD as such; it is mostly about making the advanced
technologies of Postgresql and ZFS go well together. Even ZFS developers
On Wed, 8 Jul 2009, Yaroslav Tykhiy wrote:
My conclusion is that although ZFS prefetch is supposed to be adaptive and
handle random access more or less OK, in reality there is plenty of room for
improvement, so to speak, and for now Postgresql performance can benefit from
its staying just
Hi All,
I have a mid-size database (~300G) used as an email store and running
on a FreeBSD + ZFS combo. Its PG_DATA is on ZFS whilst xlog goes to a
different FFS disk. ZFS prefetch was enabled by default and disk time
on PG_DATA was near 100% all the time with transfer rates heavily
