Agreed, and I apologize for the imprecision of my post below.
I should have written:
"Best practice seems to be to use a journaling fs and log metadata
only and put it on separate dedicated spindles."
I've seen enough HD failures that I tend to be paranoid and log the
metadata of fs dedicated to WAL as well, but that may very well be overkill.
Ron
At 01:57 PM 12/1/2005, Tom Lane wrote:
Ron <rjpeace@xxxxxxxxxxxxx> writes:
> Agreed. Also the odds of fs corruption or data loss are higher in a
> non journaling fs. Best practice seems to be to use a journaling fs
> but to put the fs log on dedicated spindles separate from the actual
> fs or pg_xlog.
I think we've determined that best practice is to journal metadata only
(not file contents) on PG data filesystems. PG does expect the filesystem
to remember where the files are, so you need metadata protection, but
journalling file content updates is redundant with PG's own WAL logging.
On a filesystem dedicated to WAL, you probably do not need any
filesystem journalling at all --- we manage the WAL files in a way
that avoids changing metadata for a WAL file that's in active use.
A conservative approach would be to journal metadata here too, though.
regards, tom lane
