Use a Workaround to Replace a Disk on a Model E or F Appliance

Use the following workaround to replace a disk on a model E or F appliance if the fdisk -l command fails to show you the name, for example, sda or sdb, of the faulty disk you want to replace. 

For this workaround, it is assumed that you have logged on to the appliance where you want to replace a disk and run the fdisk -l  command, see also Replace a Disk on a Model E or F Appliance.

When trying to locate the faulty disk with mwg-raid locate sd<x>, using the names that the fdisk -l command returned, the LED on the faulty disk did not start blinking.

Then proceed as follows:

1. Note the disk names that the fdisk -l command returned, for example, sda and sdc.

2. Try to locate the faulty disk with this command:
   
   mwg-raid locate sd<x>
   
   For <x> specify a letter that did not appear in the names returned by the fdisk -l command, for example, b. Try other letters if needed until you see that the LED on the faulty disk starts to blink.

3. Remove the disk from the RAID configuration before you remove it physically with this command:
   
   mwg-raid remove sd<x>
   
   For <x>, specify the letter found in step 2, for example, b.
   
   This removes the specified disk from all RAID volumes where it was a member. The LED on the disk turns to continuous red, as the disk status must be faulty before a disk can be physically removed.

4. Remove the old disk from the slot on the appliance hardware platform and insert the new.

5. Add the new disk to the RAID configuration with this command:
   
   mwg-raid add sd<x>
   
   For <x> specify the letter found for the faulty disk in step 2, for example, b.
   
   The new disk is added to the RAID configuration. The content of the disk that was removed is mirrored on the new disk. While this process is going on, the red LED blinks slowly.

6. Run the fdisk -l command to find out about the names of the disks that are now installed:
   
   fdisk -l | grep sd

7. To check whether the replacement has been performed correctly, run this command:
   
   mwg-raid list
   
   The command outputs, for example, the following:
    

   md0      raid1 clean
   md0:0    sda1
   md0:1    sdb1
   md1      raid1 clean
   md1:0    sda2
   md1:1    sdb2
   

   
   This shows that RAID-1 status has been set up again for the disks on the appliance.