Expanding RAID 5: 3 hdd -> 4hdd

Hi all,

my Cloud EX4 have 3 hdd. I want to expand the RAID 5 volume with one more hdd. Can i do it without losing data?



Welcome to the WD Community.

Yes, you can add a 4th drive and expand the RAID 5 without losing your data. 

Once you add the new drive, go to the dashboard and then storage, look for change RAID mode, then click on RAID 5 and under the option that says switch to JBOD it will show a new option to expand the RAID.

Further to @foschi’s question, I’ve already added a 4th drive to a 3 drive RAID 5 setup about 3 days ago. I’m not sure if it worked or not because the system has been busy ever since. The EX4 LCD screen says “SYSTEM BUSY, PLEASE WAIT”. The EX4 web interface says, “The system is busy. Please wait until the system LED turns solid blue before inserting another drive.” This is in a pop-up window which doesn’t allow me to close it or minimize it. I don’t have access to the EX4 home tab, users tab, etc.

Worse is that I can’t tell if it’s adding the fourth drive to the existing array or if it’s hung as there are no other messages. Each drive has a solid blue LED lit up, but the system LED is a blinking blue. 

My question is how long should I wait for the system to be ready? It’s already been three days! What would happen if I physically shut down the system using the power button or pulled the plug?

I have the exact same problem as previous post. Over 3 days here. Did it eventually complete whatever it was doing or did you have to do something else to fix?

I am currently going through a similar process. In my case changing from RAID1, adding a third disk and then changing to RAID5. I believe that I mistakenly chose the option to ‘migrate’. It has given me a time in minutes (just over 1000) and right now it has about 13 hours to go. It may be reasonable to assume that the job will complete by around 9:00 am tomorrow.

Just called support & was advised will take about 6 days & this is perfectly normal. 

Just an update…

Worked as expected. Did a bit of resizing and finished completely by 9:30 am. All orignal data left intact. Didn’t have much data as this was just a test set to allow me to get familiar with the system.

With mine I had originally installed 3 X 4TB drives & copied over nearly 4TB of data on RAID 5 setting before adding the 4th 4TB drive so maybe thta’s why WD have advised it will take 6 days. 4 days so far!

Hello there. This is exactly what I’m looking at doing with my EX4, adding a 4th 3tb drive to a RAID5. My question is, do the shares go offline while this process is happening? If I need an entire week of downtime on my server, I need to prepare. However, if I can still access files (perhaps no need to write) I can start now.


Can you do this in reverse? (4 hdd → 3 hdd)
I want to take one hdd out since I never use all the space but want to convert back to 3hdd setup raid 5 without losing data.