Date: Wed, 6 Jan 1999 08:47:15 +1030 From: Greg Lehey <grog@lemis.com> To: Mike Meyer <mwm@phone.net> Cc: questions@FreeBSD.ORG Subject: Re: max partitions in one slice? Message-ID: <19990106084715.S78349@freebie.lemis.com> In-Reply-To: <Pine.BSF.4.05.9901051347330.7183-100000@guru.phone.net>; from Mike Meyer on Tue, Jan 05, 1999 at 02:03:55PM -0800 References: <19990106081353.O78349@freebie.lemis.com> <Pine.BSF.4.05.9901051347330.7183-100000@guru.phone.net>
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On Tuesday, 5 January 1999 at 14:03:55 -0800, Mike Meyer wrote: > > On Wed, 6 Jan 1999, Greg Lehey wrote: >>> Hmm - considering that two file systems is at least one two few for a >>> Unix system, I'm curious as to what you're going to do with those few? >>> >>> To justify my statement, and start a discussion of file system >>> allocation, you want the following (bare miminum): >>> >>> 1) OS installed software (/ & /usr) >>> >>> 2) Spool area (/var) >>> >>> 3) Things that didn't come with the OS (i.e. - your home directory). >>> >>> On second thought, if you don't ever spool anything (i.e. - no mail, >>> no printer, nothing logged, etc.), you can get away without >>> /var. That's not very likely, though. >> >> You haven't said why you think you need separate file systems for all >> these things. It's perfectly possible to have a UNIX system with only >> one file system; I have at least one on my network, and that may be >> too few. > > Fair enough. > > Heavily-trafficed things (mail spools, printer spools, the log files) > get pulled into one area so that writes to them will be isolated > during a crash. As I say below, this is no longer an issue. > Stuff that doesn't come from the vendor gets a separate file system so > that it's got separate backups, is well out of the way for OS > upgrades, etc. That gets handled by file name, not file system. >> In general, there are three possible reasons for having more than one >> file system: >> >> 1. Security. If you break one file system, you still have the >> other. This was once a serious problem, but nowadays the systems >> are so reliable that it hardly counts. I've been running BSD for >> nearly 7 years now, and I've only had one crash (on a BSD/OS root >> file system, FWIW). Still, this and superstition are the reason >> that I accept a separate root file system on the system disk. > > That's one reason for splitting /var off from /. Not the only one, > though. It's the only one you mention. And I already said that it's not an issue. >> 2. Because they are on different disks. Vinum will solve this >> problem too. See http://www.lemis.com/vinum.html for more >> details. > > Vinum? How is this different from a RAID implementation? Not at all. >> 3. Because otherwise it would be too big to make a backup on a single >> tape. > > That's only if your backup software is truly hosed. Since the stock > software that comes with BSD supports multi-tape backups just fine, > there's no reason to worry about that. Do you like getting up three times in the middle of the night to change a tape? >> The biggest disadvantage of separate partitions is that it fragments >> your data space. In this forum we continually see people running out >> of space, usually on /var, and wanting to know what to do. If they >> hadn't had a separate /var in the first place, they wouldn't have had >> the problem. > ... > > Which is another reason for having a seperate file system: to provide > firewalls (terminology courtesy of Mike O'Dell). I split /usr off from > / on my system, in part so I don't have to worry about filling / while > mucking about with /usr/ports and thus causing real problems. Ditto > for putting your own stuff on a different file system from root, or > one where you log files, etc. That way, a runaway user process can't > cripple the system by running something critical out of space (or, > given the 10% slop, so close that it'll finish the job itself). I've never had this problem myself, but that's what quotas are for. Greg -- See complete headers for address, home page and phone numbers finger grog@lemis.com for PGP public key To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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