[Macpartners] "Degraded" OS X RAID volume...

[k_limon]

I toyed around with OS X RAID volumes back in 10.1 days, and ultimately ended
with a listable, but unreadable volume from which no data recovery was possible
(yes, I did have backups) even with our then Apple tech's attempts, so I
abandoned it seeing that it wasn't ready for primetime.

Now, I've been using it under 10.3 for some time. I currently have a workstation
with 10.3.9 and current software updates, which recently developed a "degraded"
condition on one of the two RAID1 volumes on it. But, I cannot get it fixed.

When I look at it under the Disk Utility, regardless of whether I look at the
RAID tab of the individual disks making up the mirror, or the virtual mirror
volume, [Rebuild] is grayed out.

When I run

diskutil list

and identify the virtual RAID volume/device node as disk7 and run

diskutil checkRAID disk7

I get

RAID SETS
---------

Name:           RAID1-120G
Unique ID:      RAID1-120Gbcd44c439daa11d99160003065b5fe2a
Type:           Mirror
Status:         Running
Device Node:    disk4
-------------------------------------------------------------
 #      Device Node             Status
-------------------------------------------------------------
0       disk1                   OK
1       disk2                   OK
-------------------------------------------------------------

Name:           RAID1-400G
Unique ID:      RAID1-400Gd8da5a55b61411d9ae0c003065b5fe2a
Type:           Mirror
Status:         Degraded
Device Node:    disk7
-------------------------------------------------------------
 #      Device Node             Status
-------------------------------------------------------------
0       disk5                   OK
1       disk6                   OK
-------------------------------------------------------------

I know how to repair a failed mirror with

sudo diskutil repairMirror disk7 X disk5 disk6

where X is the device node of the physical disk I want to replace, but neither
disk shows up as failed. So, as far as all indications go, the array is fine.
Why is the mirror in "Degraded" status, and how do I go about rectifying that?

-Kerem


Kerem B. Limon
kerem.limon at mit.edu /e-mail