Re: WAL documentation changes

Josh Berkus wrote:
>
> >> First, none of the general purpose filesystems I've seen so far do data
> >> journalling per default, since it's a huge performance penalty, even for
> >> non-RDBMS workloads. The feature you talk about is ext3 specific (and
> >> should be pointed out as such) and only disables write ordering, meaning
> >> that metadata and file content updates are not synchronized.
> >
> > You are right that my docs were misleading. I have improved them by
> > mentioning that it is _data_ flush that as part of journalling that can
> > be a problem, and documented that the mount option listed is
> > ext3-specific, not linux-specific.
>
> Actually, I think that some of the other journalling filesystems allow
> data journalling (I know ReiserFS does), they just don't default to it.
> For that matter, a few (ZFS in particular) have data journalling which
> can't be turned off. While it's not a tuning parameter, users should be
> warned that they'll take a performance hit from it.

So I assume you are saying the docs are fine now.

--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com

+ If your life is a hard drive, Christ can be your backup. +