Re: What is WAL used for?

On Fri, 2003-12-05 at 02:40, Thierry Missimilly wrote:

> With the data=writeback mode, I increase the TPS by 18% and dicrease the wait
> I/O from 54% to 30%.
> I did not change my filesystem to ext2 as I have to have to cancel the partition
> and recreate all the database. Futhermore, i have understood that journaled
> filesystem allowed better and faster fsck after a Power off crash and it is not
> redundant with the WAL Crash recovery.
> I think that "journaling" is at file system level and WAL is above in the
> Database level. What happen if the xlog filesystem has been breakdown by a power
> off. All the Data concisentcy done by PG will be lost. I hope that data stored
> in the FS journal, can avoid that.

What's the recommended method of changing an ext3 partition to
data=writeback mode on RH9?

I tried the tune2fs -j method to set the default journal type and
rebooted, but saw *no* performance differences, so I was wondering if
setting the default actually put it in writeback mode.

Does anyone know if there's an easy way to verify the mode, or if I'm
setting it wrong ?