Re: Best OS for Postgres 8.2

On May 8, 2007, at 2:59 AM, david@lang.hm wrote:
> one issue with journaling filesystems, if you journal the data as  
> well as the metadata you end up with a very reliable setup, however  
> it means that all your data needs to be written twice, oncce to the  
> journal, and once to the final location. the write to the journal  
> can be slightly faster then a normal write to the final location  
> (the journal is a sequential write to an existing file), however  
> the need to write twice can effectivly cut your disk I/O bandwidth  
> in half when doing heavy writes. worse, when you end up writing mor  
> ethen will fit in the journal (128M is the max for ext3) the entire  
> system then needs to stall while the journal gets cleared to make  
> space for the additional writes.

That's why you want to mount ext3 partitions used with PostgreSQL  
with data=writeback.

Some folks will also use a small filesystem for pg_xlog and mount  
that as ext2.
--
Jim Nasby                                            jim@nasby.net
EnterpriseDB      http://enterprisedb.com      512.569.9461 (cell)