On Tue, 2005-05-03 at 10:30 -0400, Brandon Craig Rhodes wrote:
> theories:
>
> a) Putting the WAL on a separate device from the database tables
> not only increases efficiency, but reliability as well - because
> as long as one keeps a database backup and a WAL history that
> goes back to the last backup (as described in 22.3 of the 8.0.1
> manual), then one is insulated from losing data from a single
> disk failure:
>
> - If the drive holding the tables fails, then take the most
> recent backup and bring it up to date using the WAL.
I assume the WAL history you mention are the WAL segments archived
for PITR. they are usually shipped to a safe place, as soon as they
are archived, but not kept on the same device as the WAL itself, if
at all possible.(often near the database backup)
Then, if either of the devices holding the database or WAL fails,
the database can be rebuilt using backup+archived WALs upto the point
of the last WAL archive.
gnari