From owner-freebsd-current Mon May 11 17:37:10 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id RAA26448 for freebsd-current-outgoing; Mon, 11 May 1998 17:37:10 -0700 (PDT) (envelope-from owner-freebsd-current@FreeBSD.ORG) Received: from Kitten.mcs.com (Kitten.mcs.com [192.160.127.90]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id RAA26407 for ; Mon, 11 May 1998 17:36:59 -0700 (PDT) (envelope-from karl@Mars.mcs.net) Received: from Mars.mcs.net (karl@Mars.mcs.net [192.160.127.85]) by Kitten.mcs.com (8.8.7/8.8.2) with ESMTP id TAA13493; Mon, 11 May 1998 19:36:47 -0500 (CDT) Received: (from karl@localhost) by Mars.mcs.net (8.8.7/8.8.2) id TAA06245; Mon, 11 May 1998 19:36:47 -0500 (CDT) Message-ID: <19980511193645.56745@mcs.net> Date: Mon, 11 May 1998 19:36:45 -0500 From: Karl Denninger To: Kirk McKusick Cc: Ollivier Robert , julian@whistle.com, Luoqi Chen , current@FreeBSD.ORG Subject: Re: Why Soft Updates are not a mount option References: <9805100336.AA06453@watermarkgroup.com> <199805112206.PAA28767@flamingo.McKusick.COM> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Mailer: Mutt 0.84 In-Reply-To: <199805112206.PAA28767@flamingo.McKusick.COM>; from Kirk McKusick on Mon, May 11, 1998 at 03:06:41PM -0700 Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG On Mon, May 11, 1998 at 03:06:41PM -0700, Kirk McKusick wrote: > Soft Updates are set in the superblock with tunefs for several reasons: > > 1) This is an interim measure during the testing phase of soft updates. > In the long run, they will always be used as the normal course of > events. I do not want legacy mount options lying around. Uh, how do you do that with the current licensing system? (ie: not everyone can play) > 2) The soft update code is not prepared to be turned on when the filesystem > is active. It currently has no code to find all files actively being > written and building up the necessary dependency information for them. > Writing such code is non-trivial and not a worthwhile exercise in my > opinion, especially given goal #1. > > 3) Fsck uses different algorithms for cleaning up on filesystems run with > soft updates. It is much more reliable to have it check for the bit in > the superblock than it is to try and figure out whether the flag was > set when it was mounted. Also, the algorithms can only be used if the > filesystem was continuously run with soft updates throughout the time > that it was mounted. If it could be updated, that would somehow have > to be recorded. > > Kirk McKusick These points certainly appear to be legit, however. But (1) concerns me. -- -- Karl Denninger (karl@MCS.Net)| MCSNet - Serving Chicagoland and Wisconsin http://www.mcs.net/ | T1's from $600 monthly / All Lines K56Flex/DOV | NEW! Corporate ISDN Prices dropped by up to 50%! Voice: [+1 312 803-MCS1 x219]| EXCLUSIVE NEW FEATURE ON ALL PERSONAL ACCOUNTS Fax: [+1 312 803-4929] | *SPAMBLOCK* Technology now included at no cost To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message