Raid 5 adding a 4th drive (Horizontal Migration ?)

I have a RAID 5 - 3 drive (4tb each) EX4 setup, can I now add a 4th drive and will the unit rebuild on all 4 drives without me having to lose any data?

From what I read on the forum there was to be a firmware update (January 2014) that would make it possible to do this. At the time of the posting December 2013, the EX4 could not do what was called “horizontal  migration”.



If you add the new drive, the unit will rebuild the RAID and the data will remain on the unit. You won’t loose any data.

I’m also having a problem adding a 4th drive to my EX4 Raid 5.  Last week I created a RAID 5 with 3 new WD Black 3TB drives.  Today I installed the new drive (also a WD Black 3TB drive) and the EX4 did its thing to format it and get it ready for use.  I can see it in the Storage > Disk Status on my dashboard, all drives show good and healthy.  I’m running firmware 1.03.41 and have gone through the steps to Change RAID Mode.  All through the process it warns that all data will be lost and there is no option to add an additional disk to the configuration.  However, I do get an option to add it as a a spare drive but thats not what I want to accomplish.

I guess what I’m getting at is, has this issue been resolved?


written by Ganesh_AT
Re: RAID Capacity Expansion

‎12-10-2013 10:14 AM

Yes, got answers for two questions:

  1. RAID expansion:

We currently support three RAID migration modes:
1. JBOD to RAID 1
2. JBOD to RAID 5
3. RAID 1 to RAID 5
With the online raid migration, we do not support that yet. This is scheduled to be released in a firmware update in late January.


Is it possable to add two new drives to an exsisting RAID 5 config? if so how. just installing them did not add them to the RAID. 

EX4 with two 3TB WD red in a RAID 5 config

Firmware ver: 1.04.04

Trying to add two more WD red 3TB