| From: | Bruce Momjian <bruce(at)momjian(dot)us> |
|---|---|
| To: | "Jonah H(dot) Harris" <jonah(dot)harris(at)gmail(dot)com> |
| Cc: | Aidan Van Dyk <aidan(at)highrise(dot)ca>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>, Brian Hurt <bhurt(at)janestcapital(dot)com>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Block-level CRC checks |
| Date: | 2008-10-02 17:38:06 |
| Message-ID: | 200810021738.m92Hc6815139@momjian.us |
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| Lists: | pgsql-hackers |
Jonah H. Harris wrote:
> On Thu, Oct 2, 2008 at 1:07 PM, Bruce Momjian <bruce(at)momjian(dot)us> wrote:
> >> If we're double-buffering the write, I don't see where we could be
> >> introducing a torn-page, as we'd actually be writing a copied version
> >> of the buffer. Will look into this.
> >
> > The torn page is during kernel write to disk, I assume, so it is still
> > possible.
>
> Well, we can't really control too much of that. The most common
> solution to that I've seen is to double-write the page (which some
> OSes already do regardless). Or, are you meaning something else?
I just don't see how writing a copy of the page (rather than the
original) to the kernel affects issues about torn pages.
--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com
+ If your life is a hard drive, Christ can be your backup. +
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