Re: moving pg_xlog -- yeah, it's worth it!

From: Bruce Momjian
Subject: Re: moving pg_xlog -- yeah, it's worth it!
Date: ,
Msg-id: 201002111129.o1BBTK518798@momjian.us
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In response to: Re: moving pg_xlog -- yeah, it's worth it!  ("Kevin Grittner")
Responses: Re: moving pg_xlog -- yeah, it's worth it!  (Scott Marlowe)
List: pgsql-performance

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moving pg_xlog -- yeah, it's worth it!  ("Kevin Grittner", )
 Re: moving pg_xlog -- yeah, it's worth it!  (Jesper Krogh, )
  Re: moving pg_xlog -- yeah, it's worth it!  ("Kevin Grittner", )
   Re: moving pg_xlog -- yeah, it's worth it!  (Amitabh Kant, )
    Re: moving pg_xlog -- yeah, it's worth it!  ("Kevin Grittner", )
   Re: moving pg_xlog -- yeah, it's worth it!  (Bruce Momjian, )
    Re: moving pg_xlog -- yeah, it's worth it!  (Scott Marlowe, )
   Re: moving pg_xlog -- yeah, it's worth it!  ("Kevin Grittner", )
    Re: moving pg_xlog -- yeah, it's worth it!  (Alvaro Herrera, )
     Re: moving pg_xlog -- yeah, it's worth it!  (Aidan Van Dyk, )
      Re: moving pg_xlog -- yeah, it's worth it!  ("Kevin Grittner", )
 Re: moving pg_xlog -- yeah, it's worth it!  ("Kevin Grittner", )
  Re: moving pg_xlog -- yeah, it's worth it!  (Alvaro Herrera, )
   Re: moving pg_xlog -- yeah, it's worth it!  (Alvaro Herrera, )
    Re: moving pg_xlog -- yeah, it's worth it!  ("Kevin Grittner", )
     Re: moving pg_xlog -- yeah, it's worth it!  (Alvaro Herrera, )
  Re: moving pg_xlog -- yeah, it's worth it!  (Greg Smith, )
   Re: moving pg_xlog -- yeah, it's worth it!  ("Kevin Grittner", )
    Re: moving pg_xlog -- yeah, it's worth it!  (Ben Chobot, )

Kevin Grittner wrote:
> Jesper Krogh <> wrote:
>
> > Sorry if it is obvious.. but what filesystem/OS are you using and
> > do you have BBU-writeback on the main data catalog also?
>
> Sorry for not providing more context.
>
> ATHENA:/var/pgsql/data # uname -a
> Linux ATHENA 2.6.16.60-0.39.3-smp #1 SMP Mon May 11 11:46:34 UTC
> 2009 x86_64 x86_64 x86_64 GNU/Linux
> ATHENA:/var/pgsql/data # cat /etc/SuSE-release
> SUSE Linux Enterprise Server 10 (x86_64)
> VERSION = 10
> PATCHLEVEL = 2
>
> File system is xfs noatime,nobarrier for all data; OS is on ext3.  I
> *think* the pg_xlog mirrored pair is hanging off the same
> BBU-writeback controller as the big RAID, but I'd have to track down
> the hardware tech to confirm, and he's out today.  System has 16
> Xeon CPUs and 64 GB RAM.

I would be surprised if the RAID controller had a BBU-writeback cache.
I don't think having xlog share a BBU-writeback makes things slower, and
if it does, I would love for someone to explain why.

--
  Bruce Momjian  <>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

  + If your life is a hard drive, Christ can be your backup. +


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