From: Anj Adu <fotographs@gmail.com>
To: Scott Marlowe <scott.marlowe@gmail.com>
Cc: Greg Smith <greg@2ndquadrant.com>
Cc: pgsql-admin@postgresql.org
Subject: Re: more 10K disks or less 15K disks
Date: Thu, 29 Apr 2010 12:35:01 -0700
Message-ID: <y2mf2fd819a1004291235wce7d12e8y6f4ae5feaf77d7f8@mail.gmail.com> (raw)
In-Reply-To: <z2gdcc563d11004291225g3e34196eu42379ae4356a1c1f@mail.gmail.com>
References: <i2pf2fd819a1004281127sf91d988cua1d95d13d09dae09@mail.gmail.com>
<4BD8DCEA.2020003@2ndquadrant.com>
<u2zf2fd819a1004282145wc60c3b39o7f0679fec9f607f8@mail.gmail.com>
<4BD9198E.904@2ndquadrant.com>
<u2yf2fd819a1004291026z89cbd919m7d11c74f9b14a1eb@mail.gmail.com>
<z2gdcc563d11004291225g3e34196eu42379ae4356a1c1f@mail.gmail.com>
With the increase in the number of disks that we can afford to have in
1 box..we will definitely plan on having WAL on dedicated disks.
Previously..we were stuck with the chassis limitation of 6 disks per
box.
On Thu, Apr 29, 2010 at 12:25 PM, Scott Marlowe <scott.marlowe@gmail.com> wrote:
> On Thu, Apr 29, 2010 at 11:26 AM, Anj Adu <fotographs@gmail.com> wrote:
>> All the disks are usually laid out in a single RAID 10 stripe . There
>> are no dedicated disks for the OS/WAL as storage is a premium
>
> You should at least investigate the performance difference of having a
> separate volume for WAL files on your system. Since WAL files are
> mostly sequential, and db access is generally random, the WAL files
> can run really quickly on a volume that does nothing else but handle
> WAL writes sequentially. Given the volume you're handling, I would
> expect that storage is not any more important than performance.
>
> The fact that you're asking whether to go with 12 or 24 600G disks
> shows that you're willing to give up a little storage for performance.
> I would bet that the 24 10k disks with one pair dedicated for OS /
> pg_xlog would be noticeably faster than any single large volume config
> you'd care to test, especially for lots of active connections.
>
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To: pgsql-admin@postgresql.org
Cc: fotographs@gmail.com, scott.marlowe@gmail.com, greg@2ndquadrant.com
Subject: Re: more 10K disks or less 15K disks
In-Reply-To: <y2mf2fd819a1004291235wce7d12e8y6f4ae5feaf77d7f8@mail.gmail.com>
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