Replace a RAID Hard Disk in OSX Based Servers

I recently had to replace a hard disk in our OSX server at work. It had been a while since I had done this so I noted down the steps here to run through and change it. Work out which disk in your machine is faulty and replace it with a new drive.

~

I recently had to replace a hard disk in our OSX server at work. It had been a while since I had done this so I noted down the steps here to run through and change it. Work out which disk in your machine is faulty and replace it with a new drive.

To get started, open up terminal and run:

sh-3.2# diskutil list

This will give you a list of all the disks in your machine:

/dev/disk0
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *1.0 TB     disk0
   1:                        EFI EFI                     209.7 MB   disk0s1
   2:                  Apple_HFS Macintosh HD            999.9 GB   disk0s2
/dev/disk1
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *1.0 TB     disk1
   1:                        EFI EFI                     209.7 MB   disk1s1
   2:                  Apple_HFS Server HD               999.3 GB   disk1s2
   3:                 Apple_Boot Recovery HD             650.0 MB   disk1s3
/dev/disk2
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *2.0 TB     disk2
   1:                        EFI EFI                     209.7 MB   disk2s1
   2:                  Apple_HFS Untitled 1              2.0 TB     disk2s2
/dev/disk3
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *2.0 TB     disk3
   1:                        EFI EFI                     209.7 MB   disk3s1
   2:                 Apple_RAID                         2.0 TB     disk3s2
   3:                 Apple_Boot Boot OS X               134.2 MB   disk3s3
/dev/disk4
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *2.0 TB     disk4
   1:                        EFI EFI                     209.7 MB   disk4s1
   2:                  Apple_HFS TimeMachine             2.0 TB     disk4s2
/dev/disk5
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                  Apple_HFS Work                   *2.0 TB     disk5

The new disk in this machine is /dev/disk2. We now need to work out the Unique ID for our RAID array. So we’ll run the following command so that we can get our Unique ID:

sh-3.2# diskutil appleraid list

Which will provide the following output:

AppleRAID sets (1 found)
===============================================================================
Name:                 2TB Mirror
Unique ID:            E07AE421-43C5-4778-B1E3-DC3365F3266B
Type:                 Mirror
Status:               Degraded
Size:                 2.0 TB (2000054943744 Bytes)
Rebuild:              manual
Device Node:          disk5
-------------------------------------------------------------------------------
#  DevNode   UUID                                  Status     Size
-------------------------------------------------------------------------------
-  -none-    82D0A9C3-5ACB-4B3C-A4FC-FD473709E186  Missing/Damaged
1  disk3s2   81D8BD2A-894F-4720-8924-D4654001CF69  Online     2000054943744
===============================================================================

Next, we’ll add this disk to the existing array, the bad disk is listed in the array above as missing, because we’ve replaced it with a new disk.

sh-3.2# diskutil appleraid add member disk2 E07AE421-43C5-4778-B1E3-DC3365F3266B

This will now perform an operation to add this disk to the RAID array:

Started RAID operation on disk5 Work
Unmounting disk
Repartitioning disk2 so it can be in a RAID set
Unmounting disk
Creating the partition map
Adding disk2s2 to the RAID Set
Finished RAID operation on disk5 Work 2012+

And you’re now done for the addition of the drive. You now need to remove the old slice from the array by using this command:

sh-3.2# diskutil appleraid remove 82D0A9C3-5ACB-4B3C-A4FC-FD473709E186 E07AE421-43C5-4778-B1E3-DC3365F3266B

You can now check that your RAID looks good by running:

sh-3.2# diskutil appleraid list

The RAID status should now be showing as online.


~

Comments