Replace damaged drive in EX4100 configuration in RAID 5

Hi all.
I have a WD EX4100 (OS 5) with four WD Red 3TB drives configured in RAID 5.
System is set to auto-rebuild RAID.
Recently drive 1 failed: first led is red, other leds are blue.
I bought one WD Red 4TB drive (higher capacity) to replace the damaged drive.
The capacity is higher because I couldn’t find a drive with the same capacity.
With system on, I removed first drive and insert the new unformatted one.
After a couple of minutes all leds went red and the system now says there’s no RAID configured.

So my questions are:

  • How do I let the system rebuild the RAID without losing data (I don’t mind losing 1TB for the unused space)?
  • If the system can’t auto-rebuild the RAID because it has higher capacity, how do I partition 3TB/1TB and format the drive from the EX4100 console or SSH? It’s network-attached and I can’t connect it to the computer using USB.

Thanks for your help.


Please refer to the following KB link: 2 and 4 Bay Internal Drive Replacement for WD My Cloud

Thanks for your reply, @Neha_07.
I’ve already followed the instructions.
RAID 5 is set to auto-rebuild but when I replace the drive, the system says that no RAID can be found.
The new drive I bought is 4TB, while the existing drives are 3TB. Could this be the problem?
Is there a way to prepare the new drive (partition and format) from the WD console in order to be accepted by the system and make the auto-rebuild process start?

Hi @roberto.tremonti , did you find a way to get your raid working again? I have the same problem

@WIWIWWII No solution, sorry. I had to recreate the RAID losing all my data.

Did you resolve this? I have a simlar issue. One of the four 3TB drives in a RAID 5 failed and I have ordered a 4TB drive to replace it. I am tempted to remove the failed drive (which now passes the disk) tests, reformat it using an external system, then re-insert and hope for the best.