Date: Mon, 11 May 1998 19:36:45 -0500 From: Karl Denninger <karl@mcs.net> To: Kirk McKusick <mckusick@McKusick.COM> Cc: Ollivier Robert <roberto@keltia.freenix.fr>, julian@whistle.com, Luoqi Chen <luoqi@watermarkgroup.com>, current@FreeBSD.ORG Subject: Re: Why Soft Updates are not a mount option Message-ID: <19980511193645.56745@mcs.net> In-Reply-To: <199805112206.PAA28767@flamingo.McKusick.COM>; from Kirk McKusick on Mon, May 11, 1998 at 03:06:41PM -0700 References: <9805100336.AA06453@watermarkgroup.com> <199805112206.PAA28767@flamingo.McKusick.COM>
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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
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