[PLUG] RAID 1 suggestions

Steve Bonds 1s7k8uhcd001 at sneakemail.com
Wed Nov 26 09:41:02 UTC 2003


On Tue, 25 Nov 2003, Steve Bonds 1s7k8uhcd001-at-sneakemail.com |PDX Linux| wrote:

> I've not had any problems putting boot, root, and even swap on a
> software RAID partition with RedHat 7 or newer.  The /boot partition
> needs separate LILO and/or GRUB entries for each half of the mirror for
> easier booting when one disk dies, but otherwise software mirroring is
> quite straightforward.

I should add that there is one problem I see often with the software
RAID-1.  Every now and then, for no apparent reason, a single disk
partition will be dropped out of the mirrored pair.  The only indication
is a message in syslog and the /proc/mdstat now shows "[U_]" instead of
the expected "[UU]".  I have a cron script that monitors this, but it can
be quite the annoyance.

I see no I/O errors logged at the time and SMART says all is well on the
drive.  It's also generally just a single partition, not the whole drive,
so I doubt it's a hardware problem.

To get the partition back I just:

raidhotadd /dev/mdX /dev/hdXX

Then wait for the resync to complete.

  -- Steve




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