On Jan 8, 2012, at 5:25 PM, Simon Riggs wrote: > On Mon, Dec 19, 2011 at 8:18 PM, Heikki Linnakangas > <heikki.linnakan...@enterprisedb.com> wrote: > >> Double-writes would be a useful option also to reduce the size of WAL that >> needs to be shipped in replication. >> >> Or you could just use a filesystem that does CRCs... > > Double writes would reduce the size of WAL and we discussed many times > we want that. > > Using a filesystem that does CRCs is basically saying "let the > filesystem cope". If that is an option, why not just turn full page > writes off and let the filesystem cope?
I don't think that just because a filesystem CRC's that you can't have a torn write. Filesystem CRCs very likely will not happen to data that's in the cache. For some users, that's a huge amount of data to leave un-protected. Filesystem bugs do happen... though presumably most of those would be caught by the filesystem's CRC check... but you never know! -- Jim C. Nasby, Database Architect j...@nasby.net 512.569.9461 (cell) http://jim.nasby.net -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
