From owner-freebsd-chat Thu Sep 28 8:55:31 2000 Delivered-To: freebsd-chat@freebsd.org Received: from neo.skynet.be (neo.skynet.be [195.238.2.53]) by hub.freebsd.org (Postfix) with ESMTP id B12FD37B422 for ; Thu, 28 Sep 2000 08:55:25 -0700 (PDT) Received: from [195.238.1.121] (brad.techos.skynet.be [195.238.1.121]) by neo.skynet.be (Postfix) with ESMTP id 20AAF6DD7; Thu, 28 Sep 2000 17:54:45 +0200 (MET DST) Mime-Version: 1.0 X-Sender: blk@pop.skynet.be Message-Id: In-Reply-To: References: Date: Thu, 28 Sep 2000 17:48:46 +0200 To: John Sconiers From: Brad Knowles Subject: Re: SGI releases XFS under GPL Cc: Johann Visagie , chat@FreeBSD.ORG Content-Type: text/plain; charset="us-ascii" ; format="flowed" Sender: owner-freebsd-chat@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org At 9:18 AM -0500 2000/9/28, John Sconiers wrote: > Can you please explain the difference in XFS and softupdates and why soft > updates would be more desireable than a journaling file system. I > understand what XFS is but based on your comments I get the feeling that > I have the wrong impression of what softupdates is and how it > performs. I know there are papers on the subject(s). Any one got a link? The key thing to "softupdates" is that it allows us to completely avoid writing certain disk meta-data updates to disk (so long as they continue to occur in a certain order), whereas log-structured journaling filesystems don't avoid those meta-data updates algtogether, they instead give us a more efficient way to handle them. A more efficient way to handle them is an improvement, but an even better improvement is to simply never do them at all. Unfortunately, I fear that "softupdates" and a log-structured journaling filesystem are mutually incompatible. Damn. You know, Kirk was just here. I should have asked him that question. -- These are my opinions -- not to be taken as official Skynet policy ====================================================================== Brad Knowles, || Belgacom Skynet SA/NV Systems Architect, Mail/News/FTP/Proxy Admin || Rue Colonel Bourg, 124 Phone/Fax: +32-2-706.13.11/12.49 || B-1140 Brussels http://www.skynet.be || Belgium "They that can give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety." -Benjamin Franklin, Historical Review of Pennsylvania. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-chat" in the body of the message