From owner-freebsd-hackers Tue Feb 6 11:37:26 2001 Delivered-To: freebsd-hackers@freebsd.org Received: from mailtoaster1.pipeline.ch (mailtoaster1.pipeline.ch [62.48.0.70]) by hub.freebsd.org (Postfix) with SMTP id 77DC437B491 for ; Tue, 6 Feb 2001 11:37:08 -0800 (PST) Received: (qmail 12287 invoked from network); 6 Feb 2001 19:33:57 -0000 Received: from unknown (HELO monzoon.net) ([195.134.133.140]) (envelope-sender ) by mailtoaster1.pipeline.ch (qmail-ldap-1.03) with SMTP for ; 6 Feb 2001 19:33:57 -0000 Message-ID: <3A805217.1D045A00@monzoon.net> Date: Tue, 06 Feb 2001 20:35:51 +0100 From: Andre Oppermann X-Mailer: Mozilla 4.74 [en] (Windows NT 5.0; U) X-Accept-Language: en MIME-Version: 1.0 To: Rik van Riel Cc: Matt Dillon , Poul-Henning Kamp , Charles Randall , Dan Phoenix , Alfred Perlstein , Jos Backus , freebsd-hackers@FreeBSD.ORG Subject: Re: soft updates and qmail (RE: qmail IO problems) References: Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG Rik van Riel wrote: > > On Tue, 6 Feb 2001, Matt Dillon wrote: > > > QMail's FAQ is totally incorrect. No major filesystem -- be it > > FFS, EX2FS, Reiser, FFS+Softupdates, guarentees that when you > > write() and close() a file that the file will then survive a disk > > crash. All these filesystems guarentee is that if a crash occurs, > > when the system reboots the filesystems will be recovered into a > > consistent state. Softupdates is considerably better at guarenteeing > > this consistency (as is something like Reiser), but if you crash a > > softupdates disk may wind up unwinding 'more' of the last few moments > > worth of operations then a normal filesystem would. And, I might add, > > Reiser is the same way. > > Reiserfs and ext3 have write-ahead logs and, AFAIK, fsync() > will not return until there is a commit point in the log. Also FFS/UFS will not return before the file and directory entry is written to the disk. > This means that fsync() will guarantee that the transactions > won't be unwound (unless I've overlooked some weird special > case situations where it is needed after all...). > > The only filesystems I can see being completely resilient > against these destructive roll-backs would be LFS and tux2. This doesnt matter. If your machine crashes while receiving a message you're never going to issue a SMTP 250 to the sending mail server and it will try again later. We don't care if this incomplete queue file survives or gets purged. -- Andre To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message