FreeBSD Install config

Paul Richards paul at freebsd-services.com
Thu Dec 20 21:58:00 GMT 2001


--On Wednesday, December 19, 2001 17:18:34 +0000 Paul Robinson
<paul at akita.co.uk> wrote:

> On Wednesday 19 December 2001  4:58 pm, Ian Pallfreeman wrote:
> 
>> > 80% of disk for /
>> > 20% of disk for /var
>> > A little bit for swap
>> 
>> Um, if you're going in this direction, why not merge /var too?
> 
> I normally do! The commonly accepted reasons why it's not a great idea
> though  are:
> 
> 1. If stuff is writing to /var and fills the disk, you're screwed - DoS, 
> badly behavioured daemons, etc. - go away for a bank holiday and come
> back to  a very poorly box
> 2. If stuff is going on / you would like some logging to still go on
> generally 3. You have to give a little something back to the guys who
> insist everything  should have it's own mountpoint. ;-)

I'm not a big fan of everything in /.

You've highlighted one of those reasons, which is that the partition sizes
act as a natural guard of something going out of control and eating up disk
space.

The other is backup strategies. You backup filesystems, not disks or
directories, but filesystems. If all you system is one big filesystem then
you have to backup the whole thing. Depending on how much disk space you've
got that might be a problem, i.e. you'll be hard pressed to find a 75GB
tape for instance.

If you split the disk into filesystems, then you can back up one at a time
to different tapes, or only backup root or /usr once a month etc.

Also, if something goes wrong, you can restore just the part of the disk
that you screwed, e.g. /var or /usr/local and you can also home in on a
single file to restore if the backups are spread across more than one tape.

So, as well as preventing the filling up of filesystems, partitions are
also important when it comes to backup strategies.

The other reason of course is that if you screw something up, like newfs,
then you don't wipe the whole disk, just one filesystem.
 
> I'm not a big fan of loads of mountpoints (as you probably guessed),
> mainly  because they're messy, painful to admin, and people always get it
> wrong. But  then, these days, I deal with boxes that have a wide range of
> uses and have  to be really flexible. If I was building a pure SMTP
> server, the above  probably wouldn't be how I'd go...

Mountpoints and filesystems aren't really related, you can have as many or
as few mountpoints scattered over as many or as few of your filesystems as
you want or need. It's a very flexible mechanism that allows you to
organically grow your total disk layout as you need to.

e.g. if you suddenly find /usr/ports is filling up the filesystem that /usr
is mounted on, well you create another big filesystem on another disk and
mount that filesystem on /usr/ports.

Paul Richards
FreeBSD Services Ltd
http://www.freebsd-services.com




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