Re: Perfomance Tuning

Bruce Momjian <pgman@candle.pha.pa.us> writes:
> Rod Taylor wrote:
>> On Fri, 2003-08-08 at 14:53, Andrew Sullivan wrote:
>>> I would give you exactly the opposite advice: _never_ use a
>>> non-journalling fs for your data and WAL.  I suppose if you can
>>> afford to lose some transactions, you can do without journalling.
>>> Otherwise, you're just borrowing trouble, near as I can tell.
>>
>> Agreed.. WAL cannot recover something when WAL no longer exists due to a
>> filesystem corruption.

> It is true that ext2 isn't good because the file system may not recover,
> but BSD UFS isn't a journalled file system, but does guarantee file
> system recovery after a crash --- it is especially good using soft
> updates.

The main point here is that the filesystem has to be able to take care
of itself; we expect it not to lose any files or forget where the data
is.  If it wants to use journalling to accomplish that, fine.

Journalling file contents updates, as opposed to filesystem metadata,
should be redundant with what we do in WAL.  So I'd recommend
journalling metadata only, if that option is available (and if Postgres
stuff is the only stuff on the disk...)

            regards, tom lane