From: | Josh Berkus <josh(at)agliodbs(dot)com> |
---|---|
To: | pgsql-hackers(at)postgresql(dot)org |
Subject: | Re: Page Checksums |
Date: | 2011-12-19 04:21:48 |
Message-ID: | 4EEEBBDC.1020005@agliodbs.com |
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Lists: | pgsql-hackers |
On 12/18/11 5:55 PM, Greg Stark wrote:
> There is another way to look at this problem. Perhaps it's worth
> having a checksum *even if* there are ways for the checksum to be
> spuriously wrong. Obviously having an invalid checksum can't be a
> fatal error then but it might still be useful information. Rright now
> people don't really know if their system can experience torn pages or
> not and having some way of detecting them could be useful. And if you
> have other unexplained symptoms then having checksum errors might be
> enough evidence that the investigation should start with the hardware
> and get the sysadmin looking at hardware logs and running memtest
> sooner.
Frankly, if I had torn pages, even if it was just hint bits missing, I
would want that to be logged. That's expected if you crash, but if you
start seeing bad CRC warnings when you haven't had a crash? That means
you have a HW problem.
As long as the CRC checks are by default warnings, then I don't see a
problem with this; it's certainly better than what we have now.
--
Josh Berkus
PostgreSQL Experts Inc.
http://pgexperts.com
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