Path: utzoo!attcan!uunet!decwrl!ucbvax!THUMPER.BELLCORE.COM!nsb From: nsb@THUMPER.BELLCORE.COM (Nathaniel Borenstein) Newsgroups: comp.soft-sys.andrew Subject: Re: Why isn't ATK more widely used? Message-ID: Date: 30 Jul 90 13:39:44 GMT References: <104405@convex.convex.com> Sender: daemon@ucbvax.BERKELEY.EDU Organization: The Internet Lines: 38 Excerpts from internet.info-andrew: 27-Jul-90 Re: Why isn't ATK more wide.. Anthony A. Datri@uunet.u (720) > My concern is that AMS/Messages might read /var/spool/mail/datri (for > example) and truncate it at the same time that binmail on the server is > trying to deliver new mail into that mailbox. This is a valid concern, but it is equally valid with ANY mailer that removes things from the spool file. Messages carefully follows the file locking conventions that were established on /usr/spool/mail files in early versions of UNIX. However, these simply DO NOT WORK RELIABLY ON NFS. That's all there is to it. AMS is no worse than any other mail reader in this situation. (Where the spool files are on local disks or AFS, or anything else that supports flock, AMS will be as reliable as any mail reader, and more reliable than the many that don't do proper locking.) You're right to be concerned about locking on /usr/spool/mail files, but you're wrong to think that AMS makes the situation any worse. You should either A. Not have your spool files on NFS (that's what we do at Bellcore), or B. Only use mailers that always leave everything in the spool files, never even deleting messages, which is ridiculous, or C. Give up on reliability. Blaming AMS for this situation is just ridiculous; AMS follows every convention there is regarding the spool file, but there is simply no established way to make the spool file mechanism secure against lost mail in the absence of flock. There are ways I could imagine doing it, but you'd have to modify the delivery program AND all the mail readers. At CMU, we build a whole new delivery system because of problems like this. I'm not saying you should do the same, just don't fool yourself into thinking that this problem has anything to do with using AMS user interfaces and you're safe if you don't use them, because it doesn't and you aren't. -- Nathaniel