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Message-ID: <535E9E09.1050502@denninger.net>
Date: Mon, 28 Apr 2014 13:29:29 -0500
From: Karl Denninger <karl@denninger.net>
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To: "pgsql-performance@postgresql.org" <pgsql-performance@postgresql.org>
Subject: Re: Revisiting disk layout on ZFS systems
References: <535E781A.5030708@denninger.net>	<535E9812.1090605@vmware.com>
	<535E98DA.7080702@denninger.net>
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On 4/28/2014 1:26 PM, Jeff Janes wrote:
> On Mon, Apr 28, 2014 at 11:07 AM, Karl Denninger <karl@denninger.net=20
> <mailto:karl@denninger.net>> wrote:
>
>
>
>     Isn't WAL essentially sequential writes during normal operation?
>
>
> Only if you have some sort of non-volatile intermediary, or are=20
> willing to risk your data integrity.  Otherwise, the fsync nature=20
> trumps the sequential nature.
>
That would be a "no" on the data integrity :-)

--=20
-- Karl
karl@denninger.net


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pe">
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    <br>
    <div class=3D"moz-cite-prefix">On 4/28/2014 1:26 PM, Jeff Janes wrote=
:<br>
    </div>
    <blockquote
cite=3D"mid:CAMkU=3D1zO6LQ0ESXswPeObOW0c538URd9Mw8LAtcps4qySRtWdQ@mail.gm=
ail.com"
      type=3D"cite">
      <div dir=3D"ltr">
        <div class=3D"gmail_extra">
          <div class=3D"gmail_quote">On Mon, Apr 28, 2014 at 11:07 AM,
            Karl Denninger <span dir=3D"ltr">&lt;<a
                moz-do-not-send=3D"true" href=3D"mailto:karl@denninger.ne=
t"
                target=3D"_blank">karl@denninger.net</a>&gt;</span> wrote=
:<br>
            <blockquote class=3D"gmail_quote" style=3D"margin:0 0 0
              .8ex;border-left:1px #ccc solid;padding-left:1ex"><br>
              <br>
              Isn't WAL essentially sequential writes during normal
              operation?</blockquote>
            <div><br>
            </div>
            <div>Only if you have some sort of non-volatile
              intermediary, or are willing to risk your data integrity.
              =C2=A0Otherwise, the fsync nature trumps the sequential nat=
ure.</div>
            <div><br>
            </div>
          </div>
        </div>
      </div>
    </blockquote>
    That would be a "no" on the data integrity :-)<br>
    <br>
    <pre class=3D"moz-signature" cols=3D"72">--=20
-- Karl
<a class=3D"moz-txt-link-abbreviated" href=3D"mailto:karl@denninger.net">=
karl@denninger.net</a></pre>
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