On Mon, Jul 9, 2012 at 08:00:48PM -0700, David Kerr wrote: > > On Jul 9, 2012, at 7:48 PM, Bruce Momjian wrote: > > > Rsync is popular with Postgres users, but I don't understand how they > > are using the default check mode (file size, modification time) to > > synchronize shut-down data directories? It seems they would have to use > > --checksum because it is too easy for files to change in the same > > second, and for a backend to write into the middle of a file. > > > > Is everyone who is using rsync with Postgres also using --checksum mode? > > > I must be missing something, if they're shut down you can't write to them. =) > > I do use rsync though for resyncing my mirror's, it's been working great so > far. I assume > that the WAL fixes anything that gets goofed up in the copy. (hopefully I've > been assuming correctly.)
If two writes happens in the middle of a file in the same second, it seems one might be missed. Yes, I suppose the WAL does fix that during replay, though if both servers were shut down cleanly, WAL would not be replayed. If you using it for a hot backup, and WAL would clean that up. -- Bruce Momjian <br...@momjian.us> http://momjian.us EnterpriseDB http://enterprisedb.com + It's impossible for everything to be true. + -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
