Is there any reason to use multiple partitions with a hardware raid?

Question

Suppose you have a server with a hardware raid controller configured for Raid 1 (so if one of the hard disks goes bad, the other essentially acts as failover until you can replace the failed disk).

I know the reasoning for using multiple partitions in linux is so that if the filesystem goes bad then it only breaks part of your system (let's say /var) rather then the entire system.

I always imagined that this was meant specifically for hardware failures, which the raid 1 should prevent.

Is it safe to put everything under one partition (plus swap space of course) when using a raid 1 array, or are there other software issues relating to the filesystem (ext3) which can occur even if hardware failures can be prevented?

Thanks for you time

Answer 1

Some ideas:

Years ago I had a Suse server that encountered an error issue (quick and constant) causing the log (/var/log/messages) to rapidly grow and as it was not on a separate partition it soon took up all the drive space causing the system to halt. Had /var/log been on a separate partition logging would have stopped (due to lack of space) but the system would not have gone down.

Home (/home) is also nice to have a separate partition as it makes upgrading a bit easier (you can install a whole new OS but leave /home as is without partitioning it).

Also, except when upgrading, /boot does not need to be mounted for normal operation, so if /boot (and/or /boot/efi) are on separate partitions and not mounted (noauto in /etc/fstab) they're protected from normal follies during operation.

Answer 2

Yes.

RAID is about high-availability and redundancy to protect against hardware failure. Partitioning is about data organization. The two are not mutually exclusive.

A common use is to put OS/System on one partition, and user files on a separate partition, so that the OS can be easily wiped and reinstalled without losing user files. You would do this even on a RAID system.