Message-ID: <5559EABB.1060405@neteven.com>
Date: Mon, 18 May 2015 15:35:55 +0200
From: Thomas SIMON <tsimon@neteven.com>
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To: pgsql-admin@postgresql.org
Subject: Re: Performances issues with SSD volume ?
References: <5559E3AD.7090109@neteven.com>
 <CAJghg4+91Hs26D23s0Dt-i7n4iYRQVN9zae5OBS2+OoFcojw5g@mail.gmail.com>
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Hi matheus,
thanks for reply.

Kernel is slightly different ; with a 3.10.23-xxxx-std-ipv6-64 kernel 
(OVH kernel) on HDD server, and  3.2.65-1+deb7u1 kernel on SSD server.
I'm using debian wheezy on both servers.

I didn't changed the 2 parameters you talk about.

Thanks,

Thomas

Le 18/05/2015 15:13, Matheus de Oliveira a écrit :
>
> On Mon, May 18, 2015 at 10:05 AM, Thomas SIMON <tsimon@neteven.com 
> <mailto:tsimon@neteven.com>> wrote:
>
>     After the change, I had the following behavior, and I don't
>     understand why : everything seems to work fine (load is ~6/7, when
>     it was previously ~25/30 on the HDD server), so the SSD server is
>     faster than the HDD one, and my apps run faster too, but after
>     some time (can be 5 minutes or 2 hours), the load average
>     increases suddently (can reach 150 !) and does not decrease, so
>     postgres and my application are almost unusable. (even small
>     requests are in statement timeout)
>
>
> Before we go mad, what is the OS/kernel/distro that you are using? Did 
> it change from the previous one?
>
> If Linux, have you disabled transparent_huge_pages and 
> zone_reclaim_mode (two known problematic Linux features)?
>
> Best regards,
> -- 
> Matheus de Oliveira
> Analista de Banco de Dados
> Dextra Sistemas - MPS.Br nível F!
> www.dextra.com.br/postgres <http://www.dextra.com.br/postgres/>
>


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    <div class="moz-cite-prefix">Hi matheus,<br>
      thanks for reply.<br>
      <br>
      Kernel is slightly different ; with a 3.10.23-xxxx-std-ipv6-64
      kernel (OVH kernel) on HDD server, and  3.2.65-1+deb7u1 kernel on
      SSD server.<br>
      I'm using debian wheezy on both servers.<br>
      <br>
      I didn't changed the 2 parameters you talk about.<br>
      <br>
      Thanks,
      <pre class="moz-signature" cols="72">Thomas</pre>
      Le 18/05/2015 15:13, Matheus de Oliveira a écrit :<br>
    </div>
    <blockquote
cite="mid:CAJghg4+91Hs26D23s0Dt-i7n4iYRQVN9zae5OBS2+OoFcojw5g@mail.gmail.com"
      type="cite">
      <div dir="ltr">
        <div class="gmail_extra"><br>
          <div class="gmail_quote">On Mon, May 18, 2015 at 10:05 AM,
            Thomas SIMON <span dir="ltr">&lt;<a moz-do-not-send="true"
                href="mailto:tsimon@neteven.com" target="_blank">tsimon@neteven.com</a>&gt;</span>
            wrote:<br>
            <blockquote class="gmail_quote" style="margin:0 0 0
              .8ex;border-left:1px #ccc solid;padding-left:1ex">
              After the change, I had the following behavior, and I
              don't understand why : everything seems to work fine (load
              is ~6/7, when it was previously ~25/30 on the HDD server),
              so the SSD server is faster than the HDD one, and my apps
              run faster too, but after some time (can be 5 minutes or 2
              hours), the load average increases suddently (can reach
              150 !) and does not decrease, so postgres and my
              application are almost unusable. (even small requests are
              in statement timeout)</blockquote>
          </div>
          <br>
        </div>
        <div class="gmail_extra">Before we go mad, what is the
          OS/kernel/distro that you are using? Did it change from the
          previous one?<br>
          <br>
          If Linux, have you disabled transparent_huge_pages and
          zone_reclaim_mode (two known problematic Linux features)?<br>
        </div>
        <div class="gmail_extra"><br clear="all">
        </div>
        <div class="gmail_extra">Best regards,<br>
        </div>
        <div class="gmail_extra">-- <br>
          <div class="gmail_signature">Matheus de Oliveira<br>
            Analista de Banco de Dados<br>
            Dextra Sistemas - MPS.Br nível F!<br>
            <a moz-do-not-send="true"
              href="http://www.dextra.com.br/postgres/" target="_blank">www.dextra.com.br/postgres</a><br>
            <br>
          </div>
        </div>
      </div>
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