Software RAID Problems under Mac OS X
From time to time, my software RAID 1 behaves ugly. After sleep periods for instance, it ejects and is no longer in sync.
Today, I read an article from Apple, which seems to address my problem.
They are using diskutil on the command line and it seems to provide more information about the RAID’s status than the Disk Utility GUI.
It presents information like this.
sudo diskutil checkRAID
AppleRAID sets (1 found)
====================================================================
Name: Backup
Unique ID: 0F11E679-27C7-4F05-BA57-1C7410EC048F
Type: Mirror
Status: Online
Size: 749.7 GB (749678166016 Bytes)
Rebuild: automatic
Device Node: disk4
--------------------------------------------------------------------
# Device Node UUID Status
--------------------------------------------------------------------
0 disk3s2 D560FCB5-14FE-4838-8D97-A03CA6B387B9 Online
- disk1s2 859CAE06-A75C-426C-944A-BBA5E28F6FDA Spare
====================================================================
Note, that this output was produced after I cleaned up some stuff.
I had a non existent third disk for example, which was identified to be in the RAID set - the UUID was similar to the one of device disk1s2.
The entry Rebuild was set to manual before I invoked:
sudo diskutil appleRAID update AutoRebuild 1 disk4
The fact, that disk1s2 has the status Spare still bugged me.
Hence, I removed the disk from the RAID set again using the following command:
diskutil appleRAID remove BD91D31E-E311-4980-B756-1E9343F6CEA7 0F11E679-27C7-4F05-BA57-1C7410EC048F
Then, I re-added the disk using the following command - note that you can no longer use the UUID, as the drive lost it:
diskutil appleRAID add member disk1s2 0F11E679-27C7-4F05-BA57-1C7410EC048F
Now, a three hour rebuild process has been initiated, for which end I am still waiting now ;)
Cheers,
iss