(no subject)

[markw at mohawksoft.com (markw at mohawksoft.com)]

Sorry to top post, but I'm getting this off the digest.

Contrary to this message, etx3 is a bad file system for databases. Every
benchmark I have seen and run show that the cost of journalling is
overwhelming. Under heavy load, I've seen ext3 affect performance
dramatically, sometimes on an order of magnitude.

Databases like PostgreSQL and Oracle, and probably Domino, manage
"fsync()" calls. That is, they take care of making sure page file is
flushed to disk.




From: dsr at tao.merseine.nu
Date: Fri, 8 Oct 2004 01:03:05 +0000
To: "Mark J. Dulcey" <mark at buttery.org>
Cc: Eric <235u at comcast.net>, discuss at blu.org
Subject: Re: What version and is it free for download

On Thu, Oct 07, 2004 at 04:37:06PM -0400, Mark J. Dulcey wrote:
> Eric wrote:
> >markw at mohawksoft.com wrote:
> >| Domino is "more or less" a database, and as such, you should make sure
> >| that the distribution you use supports IBM's jfs, or default to ext2.
> >ext3
> >| is horrible for database work.
> >
> >Why is ext3 horrible for database work?  My experience with databases
> >are minimal and I'm just curious.  Thanks.
>
> Linux Gazette did some benchmarking of Linux file systems
> (http://linuxgazette.net/102/piszcz.html). Their tests concluded that
> ext3 is the slowest overall of the journaling file systems, and
> particularly bad at handling large files, which will happen a lot when
> you're using it to store a database.

They forgot, however, how infrequently a real database will
create or delete a large file.... essentially never.

If you are using the filesystem *as* a database, there are
better choices. But for storing an Oracle, MySQL or PostgreSQL
db, the filesystems all handle about the same... and ext3 comes
out ahead for stability.

-dsr-