Date: Tue, 5 Jan 1999 14:38:16 -0800 (PST) From: Mike Meyer <mwm@phone.net> To: questions@FreeBSD.ORG Subject: Re: max partitions in one slice? Message-ID: <Pine.BSF.4.05.9901051425370.7183-100000@guru.phone.net> In-Reply-To: <19990106084715.S78349@freebie.lemis.com>
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On Wed, 6 Jan 1999, Greg Lehey wrote: > > > > 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. You said it twice now, and even provided circumstancial evidence the first time. I'd *still* rather be safe than sorry. I've repaired more than enough file systems in my time. > > 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. Inadequately. Since you're dumping by FS (and you are, otherwise you wouldn't worry about dump tape size vs. file system size), you wind up with mixed backup. I guess if you limit your file system size to one dump tape, there's no problem with lugging tapes full of OS software around to restore user stuff, but I'd rather not live with that limit. This one cuts in both directions, of course. > >> 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. No, it's the only one I mention *here*. If you'd finished reading what I wrote, you'd have found the other one. > >> 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? Nope. I don't, either. Tape changes only need to happen for full backups. Incrementals live on one type (or one CD-ROM, or one JAZ platter, or whatever). That's if you run large-iron backup software. If you run PC-style (clone the whole disk), then yeah, you have to live with that kind of restriction. As I already said, I'd rather not. > >> 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. Quotas are both more expensive (in terms of CPU) and less effective than putting potential offenders in different file systems. And it doesn't work particularly well when the potential offender is root. <mike To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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