8.0-RELEASE -> -STABLE and size of /
Jeremy Chadwick
freebsd at jdc.parodius.com
Sat Jan 23 20:21:50 UTC 2010
On Sat, Jan 23, 2010 at 09:04:57PM +0100, Miroslav Lachman wrote:
> Jeremy Chadwick wrote:
>
> [...]
>
> >While I'm here, I figure I'd share how I end up partitioning most of the
> >server systems I maintain. I use this general "formula" when building a
> >new system, unless it's a 4-disk box (see bottom of mail):
> >
> >ad4s1a = / = UFS2 = 1GB
> >ad4s1b = swap = (2*RAM) or (2*MaxRAMPossible)
> >ad4s1d = /var = UFS2+SU = 16GB (mandatory: must be>= 2*RAM)
> >ad4s1e = /tmp = UFS2+SU = (2*RAM)
> >ad4s1f = /usr = UFS2+SU = 16GB
>
> Why you are suggesting /var >= 2*RAM? Is it just for saving crash
> dumps or anything else?
1) Kernel panics/crash dumps are a big focus, yes. There's nothing
worse than experiencing one, only to find out that savecore(8) can't do
its job because /var/crash lacks the space. The system then boots
anyway, swap starts getting used as normal, and the dump is therefore
lost. Chance of debugging this post-mortem: zero.
Additionally, people these days are often upgrading RAM in their systems
as well; they start out with 1-2GB and create /var possibly with the
knowledge of the above ordeal (re: crash dumps). Then they later
upgrade to 4GB or 8GB RAM, and suddenly realise that they can't grow
/var to deal with a crash dump.
2) I tend to keep a large amount of logs on systems, going back weeks if
not months. This is intentional; it's amazing how often a customer or
user will ask for some information from 3 or 4 months prior.
FreeBSD's Apache port out-of-the-box logs to /var/log/httpd-*, and what
we do is mostly web content serving. Let's also not forget about
/var/log/maillog. I also advocate use of /var/log/all.log.
I think it's fairly well-established at this point that I focus on
server environments and not workstations (where /var probably doesn't
need to be anywhere near that size). Folks should always review their
needs, keeping expansion possibility in mind, when doing filesystem
creation.
> And why so big /tmp? I am running servers with smaller sizes for years
> without any problem.
My recommendation above doesn't imply those who don't use it will have
problems -- each environment/system is different.
That said, it's amazing how much software out there blindly uses /tmp.
Last year I ran into this situation: an older server (1GB /tmp) started
behaving oddly due to /tmp filling. A user of the system was using lynx
to download some large files (an ISO image and something else, I forget
what). lynx saves data its downloading to /tmp, and once it completes,
the user is prompted where to save the data (CWD being the default).
"So tune lynx to use /var/tmp or some other path" -- sure, that'd work,
except lynx is just one of many programs which could do this. I'd
rather not "tune them all". :-) /tmp is more or less universal.
Hope this sheds some light on my decisions. :-)
--
| Jeremy Chadwick jdc at parodius.com |
| Parodius Networking http://www.parodius.com/ |
| UNIX Systems Administrator Mountain View, CA, USA |
| Making life hard for others since 1977. PGP: 4BD6C0CB |
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