Date: Fri, 17 Feb 2012 16:54:36 -0800 From: Devin Teske <devin.teske@fisglobal.com> To: "'Chuck Swiger'" <cswiger@mac.com> Cc: 'FreeBSD -' <freebsd-questions@freebsd.org> Subject: RE: One or Four? Message-ID: <021901ccedd7$e3724490$aa56cdb0$@fisglobal.com> In-Reply-To: <FF97816E-74EE-434C-BB04-A8F21C07AF10@mac.com> References: <4F3ECF23.5000706@fisglobal.com> <20120217234623.cf7e169c.freebsd@edvax.de> <20120217225329.GB30014@gizmo.acns.msu.edu> <021101ccedc9$89445cf0$9bcd16d0$@fisglobal.com> <290E977C-E361-4C7D-8F1E-C1D6D03BAD63@mac.com> <021501ccedd1$ef4201d0$cdc60570$@fisglobal.com> <FF97816E-74EE-434C-BB04-A8F21C07AF10@mac.com>
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> -----Original Message----- > From: Chuck Swiger [mailto:cswiger@mac.com] > Sent: Friday, February 17, 2012 4:41 PM > To: Devin Teske > Cc: 'FreeBSD -' > Subject: Re: One or Four? > > On Feb 17, 2012, at 4:11 PM, Devin Teske wrote: > >> However, for whatever reasons, the overwhelming majority of folks using > MacOS > >> X don't have problems using a single root partition, and while they sometimes > do > >> fill up their disks, that's a situation which they should be able to recover from > >> without needing expert assistance. I don't recall having unusual issues in > running > >> a partition out of space under FreeBSD, either, or difficulty fixing things > >> afterwards-- > > > > Recipe for disaster: > > > > 1. You have a cron-job that pulls down /etc/master.passwd daily > > 2. Your cron-job also runs pwd_mkdb after "SUP"ing down /etc/master.passwd > > Yes, I agree that this is a recipe for disaster; the reasons not very correlated to > disk space, however. > > Even twenty years ago, handling this via YP/NIS or NetInfo would have made > more sense, and nowadays folks would be far more likely to use LDAP as the > network user database, instead of pushing system password database changes > via SUP or similar replication mechanism locally to individual hosts. > > > 3. A program fills "/" > > 4. cron fires > > 5. pwd_mkdb can't generate databases because not enough room on > filesystem > > 6. System can no longer be logged into > > #5 does not imply #6: if pwd_mkdb can't build a temporary version to > /etc/pwd.db.tmp & /etc/spwd.db.tmp, it will exit with an error rather than > invoke rename(2) to replace the working version of the password database with > something that might be broken. > Ok, then this is a departure from versions of yester-year. Glad to know that a temporary DB is built rather than rebuilding on-top of the existing DB (which last I checked 4.11 still does). > To be very specific, I would expect one to get: > > "/: write failed, filesystem is full > pwd_mkdb: /etc/pwd.db to /etc/pwd.db.tmp: No space left on device" > Yeah, 4.11 wasn't so nice. > > 7. System is rebooted > > 8. Can't log in (not even as root) > > 9. Go into single-user mode > > 10. No space to work in > > > > Sure... you can call it an "edge-case," but it's pretty common and this is only > > one of a myriad of ways we can reproduce the problem of filling-up "/" to cause > > major headaches. > > > I've never heard of such a thing happening to a real FreeBSD system in the past > decade or more. Only only needs to go back to 4.11 for this time-bomb (which still bites us at least once every 6-12 months in production -- mind you we still employ about 3,000 4.x systems and are migrating to 8.x this year). -- Devin _____________ The information contained in this message is proprietary and/or confidential. If you are not the intended recipient, please: (i) delete the message and all copies; (ii) do not disclose, distribute or use the message in any manner; and (iii) notify the sender immediately. In addition, please be aware that any message addressed to our domain is subject to archiving and review by persons other than the intended recipient. Thank you.
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