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Re: Block-level CRC checks

From: Bruce Momjian <bruce(at)momjian(dot)us>
To: Simon Riggs <simon(at)2ndQuadrant(dot)com>
Cc: Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Aidan Van Dyk <aidan(at)highrise(dot)ca>, Alvaro Herrera <alvherre(at)commandprompt(dot)com>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Block-level CRC checks
Date: 2009-12-01 12:42:10
Message-ID: 200912011242.nB1CgAr22870@momjian.us (view raw or flat)
Thread:
Lists: pgsql-hackers
Simon Riggs wrote:
> On Tue, 2009-12-01 at 07:05 -0500, Bruce Momjian wrote:
> 
> > I assume torn pages are 99% of the reported problem, which are
> > expected and are fixed, and bad hardware 1%, quite the opposite of your
> > numbers above.
> 
> On what basis do you make that assumption?

Because we added full page write protection to fix the reported problem
of torn pages, which we had on occasion;  now we don't.  Bad hardware
reports are less frequent.

And we know we can reproduce torn pages by shutting of power to a server
without battery-backed cache.  We don't know how to produce I/O failures
on demand.

-- 
  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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Subject: Re: Block-level CRC checks
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