From owner-freebsd-hackers Tue Feb 6 11:29:26 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 75FA237B401 for ; Tue, 6 Feb 2001 11:29:06 -0800 (PST) Received: (qmail 12070 invoked from network); 6 Feb 2001 19:25:55 -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 19:25:55 -0000 Message-ID: <3A805035.C71AAD5E@monzoon.net> Date: Tue, 06 Feb 2001 20:27:49 +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: Mike Silbersack , Poul-Henning Kamp , Charles Randall , 'Matt Dillon' , 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, Mike Silbersack wrote: > > On Tue, 6 Feb 2001, Rik van Riel wrote: > > > > > The system call used to guarantee this is fsync (and friends?); > > > if qmail doesn't use it but makes assumptions that aren't true > > > on any decent OS out there ... > > > > Well, the various qmail programs do seem to fsync (though I'm > > not sure if it's in the right places.) > > > ftp://elektroni.ee.tut.fi/pub/qmail_linux_metadata_message : > > > So what is this all about? qmail relies on the BSD semantics of > ^^^ > > immediate update of directories on the disk when link(), > > unlink(), open() and rename() calls are used. > > Pre-softupdate BSD semantics, apparently. Doesn't sound like > the smartest thing to do when you want a reliable MTA... This description is not entirely right. Qmail depends on ordered-metadata updates (Terry! :-). That means if you issue a link() to the new place and a unlink() in the old place it should guarantee that the link() happens *BEFORE* the unlink(). At least standard FFS/UFS does this. Linux ext2 might do the the unlink() before the link() and a crash in that moment will loose the file completely. It is all about the ordering guarantee. > > But Linux writes them to the disk asynchronously. My library > > loaded before libc changes those calls to do the corresponding > > directory writes too. Then qmail should be reliable against > > power outages also in Linux. > > If djb could be considered to take things like reliability > and the SMTP specification into account, and not just > security, then qmail would have the potential to be a pretty > decent mailer. He did and qmail is one of the best and most reliable mailers on the Internet. > As it is, I can only recommend people to go with something > like postfix, Exim or zmailer ... Have a look at the qmail source and the facts before you spill out such a *bullshit*! -- Andre To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message