You've already received some good responses so I won't rehash a
lot of what was said. However here are few more comments without
a lot of backing detail (but it should give you enough info to
google for detail):
1. Despite the RedHat link someone provided, I think the advice of
putting almost everything on the root filesystem is a lot of
bunk, at least for servers. The old arguments for separate
filesystems still apply. I suspect that the single filesystem
perspective is coming from desktop scenarios, and especially
laptop users and those coming from MS Windows.
2. Putting /boot on its own filesystem and using LVM for everything
else is a generally good idea from both the management and
snapshot perspectives as someone previously described. However be
aware that most (if not all) LVM configurations will disable
write barriers -- this is probably mostly of interest for when
you're running a database. You need to put on your combined
DBA and sysadmin hat, have a look at your underlying disks,
disk controller, filesystem stack, database, UPS/powerfail
monitoring, and budget to see where your balancing point is.
Yes, I have databases on LVM on top of RAID on top of SATA;
but it's better to know your risks rather than having them
be a surprise.
3. Pay attention to whether your disks are using the old 512 byte
sector size or the new 4k sector size (sometimes called advanced
disk format), and whether or not your disks lie to the OS about
the sector size. The RAID, other MD layers, and filesystem
need to know the truth or you can run into performance and/or
lifespan issues.
4. Regarding swap: Yes, having it is still a good idea under most
circumstances. The old "2 * physical memory" rule no longer applies.
Follow the sizing guidelines from RedHat that someone posted.
The kernel is smart enough to use it when necessary and avoid it
otherwise. Having it can get your server through unusual circumstances
without crashing but you should have enough memory that you're not
paging under normal circumstances. See also point #6.
5. Consider encrypting swap. See crypttab(5), including the comments
about using /dev/urandom for the key.
6. Putting /tmp on tmpfs is a good idea in that it ensures that it
gets cleaned out at least when the system reboots. (Running cron
jobs to clear it out periodically can cause problems; under some
circumstances.) This is a good argument to have swap; you can
use tmpfs without a significant impact of /tmp using up physical
RAM. Also see the 'tmp' option in crypttab(5).
7. Under CentOS 5 having less than 2G for /var could cause problems
with updates, especially between minor versions. I've increased
my minimum to 4G under RHEL6 due to kdump concerns.
Devin
_______________________________________________
CentOS mailing list
CentOS@xxxxxxxxxx
http://lists.centos.org/mailman/listinfo/centos
