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Re: Block-level CRC checks

From: Andrew Chernow <ac(at)esilo(dot)com>
To: Joshua Drake <jd(at)commandprompt(dot)com>
Cc: Jeffrey Baker <jwbaker(at)gmail(dot)com>, Bruce Momjian <bruce(at)momjian(dot)us>, Alvaro Herrera <alvherre(at)commandprompt(dot)com>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Block-level CRC checks
Date: 2008-10-01 01:20:30
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-hackers
Joshua Drake wrote:
> During a 41-month period we observed more than 400,000 instances of
> checksum mistmatches, 8% of which were discovered during RAID
> reconstruction, creating the possibility of real data loss.
> They also have a wonderful term they mention, "Silent Data corruptions".


 From my experience, the only assumption to be made about storage is that it can 
and will fail ... frequently!  It is unreliable (not to mention slooow) and 
should not be trusted; regardless of the price tag or brand.

This could help detect:

- fs corruption
- vfs bug
- raid controller firmware bug
- bad disk sector
- power crash
- weird martian-like raid rebuilds

Although, this idea won't prevent anything.  Everything would still sinisterly 
fail on you.  The difference is, no more silence.

Andrew Chernow
eSilo, LLC
every bit counts

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