Re: Finding bottleneck

From: Tom Lane
Subject: Re: Finding bottleneck
Date: ,
Msg-id: 8434.1123529245@sss.pgh.pa.us
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In response to: Re: Finding bottleneck  (Kari Lavikka)
List: pgsql-performance

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Finding bottleneck  (Kari Lavikka, )
 Re: Finding bottleneck  (Gavin Sherry, )
 Re: Finding bottleneck  (Claus Guttesen, )
 Re: Finding bottleneck  ("Merlin Moncure", )
 Re: Finding bottleneck  ("Luke Lonergan", )
  Re: Finding bottleneck  (Kari Lavikka, )
   Re: Finding bottleneck  (Tom Lane, )
 Re: Finding bottleneck  ("Merlin Moncure", )
  Re: Finding bottleneck  (Tom Lane, )
  Re: Finding bottleneck  (Kari Lavikka, )
   Re: Finding bottleneck  (Tom Lane, )
    Re: Finding bottleneck  (Kari Lavikka, )
     Re: Finding bottleneck  (Tom Lane, )
    Re: Finding bottleneck  (Kari Lavikka, )
     Re: Finding bottleneck  (Tom Lane, )
 Re: Finding bottleneck  (Ron, )
 Re: Finding bottleneck  ("Merlin Moncure", )
  Re: Finding bottleneck  (Tom Lane, )
 Re: Finding bottleneck  ("Merlin Moncure", )
 Re: Finding bottleneck  ("Merlin Moncure", )
  Re: Finding bottleneck  (Tom Lane, )
 Re: Finding bottleneck  ("Merlin Moncure", )

Kari Lavikka <> writes:
> Disk configurations looks something like this:
>    sda: data (10 spindles, raid10)
>    sdb: xlog & clog (2 spindles, raid1)
>    sdc: os and other stuff

That's definitely wrong.  Put clog on the data disk.  The entire point
of giving xlog its own spindle is that you don't ever want the disk
heads moving off the current xlog file.  I'm not sure how much this is
hurting you, given that clog is relatively low volume, but if you're
going to go to the trouble of putting xlog on a separate spindle then
it should be a completely dedicated spindle.

            regards, tom lane


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