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Xref: sserve comp.unix.bsd:11950 comp.mail.misc:10664 Newsgroups: comp.unix.bsd,comp.mail.misc Path: sserve!newshost.anu.edu.au!munnari.oz.au!constellation!convex!convex!cs.utexas.edu!zaphod.mps.ohio-state.edu!sol.ctr.columbia.edu!destroyer!cs.ubc.ca!unixg.ubc.ca!kakwa.ucs.ualberta.ca!acs.ucalgary.ca!cpsc.ucalgary.ca!xenlink!fsa.ca!deraadt From: deraadt@fsa.ca (Theo de Raadt) Subject: Re: mailbox locking In-Reply-To: conklin@kaleida.com's message of 28 Apr 93 12: 18:20 Message-ID: <DERAADT.93Apr29121043@newt.fsa.ca> Sender: news@fsa.ca Nntp-Posting-Host: newt.fsa.ca Organization: little lizard city References: <CONKLIN.93Apr28121820@ngai.kaleida.com> Date: Thu, 29 Apr 1993 19:10:43 GMT Lines: 31 In article <CONKLIN.93Apr28121820@ngai.kaleida.com> conklin@kaleida.com (J.T. Conklin) writes: > If I'm not mistaken, BSD once used a lock file to mail the mailbox. > 386BSD's mail.local uses kernel locks only. > > I've heard that using locking kernel locks over NFS has been > problematic. Have those problems been fixed, or should I avoid > networked mail directories? Yes, this is a problem. I myself feel that username.lock files should still be used for locking since 1) NFS is the usual case when this is needed, and there isn't a public rpc.lockd (any volunteers? I didn't think so :-) 2) as recent posts indicate, the NET2 lockf() system call has a few "problems". 3) Interoperability with mail agents on sunos and ultrix and other operating systems would be nice. I don't have a machine here that I can confirm with, but I suspect that SVR4 (the kitchen sink unix implimentation) would use BOTH varieties of locks for completeness (yuck). I don't advocate that though. At least on Sunos (probably also with NET2?), there is also the problem where /usr/ucb/Mail will loop forever (with SIGINT redirected) trying to create a lock file, forcing the user to type ^Z and kill %%. The lock files aren't perfect, but then, neither is rpc.lockd (nor will it ever). <tdr. -- This space not left unintentionally unblank. deraadt@fsa.ca