On 17.12.2011 23:33, David Fetter wrote:
> What:
>
> Please find attached a patch for 9.2-to-be which implements page
> checksums. It changes the page format, so it's an initdb-forcing
> change.
>
> How:
> In order to ensure that the checksum actually matches the hint
> bits, this makes a copy of the page, calculates the checksum, then
> sends the checksum and copy to the kernel, which handles sending
> it the rest of the way to persistent storage.
>...
> If this introduces new failure modes, please detail, and preferably
> demonstrate, just what those new modes are.
Hint bits, torn pages -> failed CRC. See earlier discussion:
http://archives.postgresql.org/pgsql-hackers/2009-11/msg01975.php
-- Heikki Linnakangas EnterpriseDB http://www.enterprisedb.com