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RE: Drastic performance difference with subversion client on Sola ris 9

From: Schernau, Ed <Edward.Schernau_at_CITIZENSBANK.com>
Date: 2004-03-30 19:49:04 CEST

Remember that if you're running Solaris 7 or later, you can always activate
journalling on a filesystem with the 'logging' option in /etc/vfstab.

-----Original Message-----
From: Greg Hudson [mailto:ghudson@MIT.EDU]
Sent: Tuesday, March 30, 2004 12:19 PM
To: ron@bieberlabs.com
Cc: dev@subversion.tigris.org; users@subversion.tigris.org
Subject: Re: Drastic performance difference with subversion client on
Solaris 9

On Tue, 2004-03-30 at 07:04, Ron Bieber wrote:
> As Linux file systems default to nosynch and I've never had a problem
> with boxes losing data in power failures here at home, I don't see a
> big problem with this as long as the box isn't running an oracle
production
> database or something like that. Given the fact that the computer room
> at work has interruptible power and backup generators anyway, I see
> even less of a problem.

The situation is somewhat more complicated than you give it credit for in
your first sentence.

The Linux ext2 filesystem behaves as you say, with completely asynch writes
and no particular attention to ensuring failure atomicity of any kind. But
it does have a pretty sophisticated fsck designed to get a filesystem back
into working order in the face of failures. (It can't protect against
certain kinds of problems, like data blocks containing data from the wrong
files, but at least it won't throw up its hands in disgust and tell you to
newfs.)

Modern Linux filesystems (reiser, xfs, ext3) have asynchronous file creation
but use techniques (careful ordering or journals) to make sure that the
on-disk filesystem is consistent at all times. As a result, they tend to be
a little slower than ext2, but most safer. Most people who use Linux these
days use one of these filesystems.

Solaris with asynch writes has neither the advantage of a sophisticated fsck
(as far as I know) nor the advantage of ordered writes or journaling.
Although you stand a pretty good chance of being okay in the face of an
unclean shutdown, it's not very safe at all.

So, feel free to rely on backups and uninterruptable power; those are fine
things. But I don't think you can rely on the experience of Linux users.

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Received on Tue Mar 30 19:51:03 2004

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