On Tue, Apr 28, 2009 at 12:06 PM, Kenneth Marshall <ktm@rice.edu> wrote:
> On Tue, Apr 28, 2009 at 11:56:25AM -0600, Scott Marlowe wrote:
>> On Tue, Apr 28, 2009 at 11:48 AM, Whit Armstrong
>> <armstrong.whit@gmail.com> wrote:
>> > Thanks, Scott.
>> >
>> > Just to clarify you said:
>> >
>> >> postgres. ?So, my pg_xlog and all OS and logging stuff goes on the
>> >> RAID-10 and the main store for the db goes on the RAID-10.
>> >
>> > Is that meant to be that the pg_xlog and all OS and logging stuff go
>> > on the RAID-1 and the real database (the
>> > /var/lib/postgresql/8.3/main/base directory) goes on the RAID-10
>> > partition?
>>
>> Yeah, and extra 0 jumped in there. Faulty keyboard I guess. :) OS
>> and everything but base is on the RAID-1.
>>
>> > This is very helpful. ?Thanks for your feedback.
>> >
>> > Additionally are there any clear choices w/ regard to filesystem
>> > types? ?Our choices would be xfs, ext3, or ext4.
>>
>> Well, there's a lot of people who use xfs and ext3. XFS is generally
>> rated higher than ext3 both for performance and reliability. However,
>> we run Centos 5 in production, and XFS isn't one of the blessed file
>> systems it comes with, so we're running ext3. It's worked quite well
>> for us.
>>
>
> The other optimizations are using data=writeback when mounting the
> ext3 filesystem for PostgreSQL and using the elevator=deadline for
> the disk driver. I do not know how you specify that for Ubuntu.
Yeah, we set the scheduler to deadline on our db servers and it
dropped the load and io wait noticeably, even with our rather fast
arrays and controller. We also use data=writeback.