How do I "Expand Capacity" on my EX4100?


I started with the EX4100 (24TB) kit.
I had the typical drive failure due to the inferior standard 6TB drives provided with the unit.
I received the replacement and instead wanted to expand capacity with the 10TB drives so installed this. The RAID5 was rebuilt, but is missing some capacity and now have the remaining 4TB un-allocated currently. How do I add this into the RAID5 I have currently?.
What are the ACTUAL steps for doing this? I have not been able to find a step-by-step instruction on how to “Expand Capacity” of my RAID5. It seems like it wants to go through and force me to replace drives instead of just allowing me to allocate the remaining empty partition of the 10TB drive to be included in the current RAID5 designation.

Is there a standard process?
The ‘Search’ function is less than adequate here and does not return what I search for.

The closest I found was this thread depicting some steps, except I have already installed the 10TB drive.
o If I run this, remove the 10TB drive, and then just put it back in, will it reallocate or not?
o If I run this, will I have to replace all drives to redefine the RAID5?
o Is there an actual document that depicts this, or any, method involved based on my current RAID configuration and an already instilled drive? (This would be really nice to have WD!!, because there is NOTHING in the User Manual about this function and “Product Features” is a dead link.).

Thanks for help/advice/etc.


Hi offroadace,

You have setup the RAID5 on your device and your My Cloud enclosure have 3 * 6TB and one 10TB drive setup.

Due to RAID setup on your device, your device is able to rebuild the RAID with only 6TB partition on the 10TB drive and leaving the remaining 4TB space on the drive as un-allocated which cannot be used in anyway.

You can use the full storage of all the drives by using the JBOD setup on your My Cloud device.


Thanks. I have been finding more info on RAID5 and that it is a limitation of the software. Some allow different drive speeds and sizes, but the size is a limitation.

Do you know of a process that would allow for an upgrade of all 4 drives to 10TB?

If I replace the current drives 1 by 1 then the partition will remain at 6TB. How would I define them as 10TB?
Would I need to offload the data externally and then build the entire NAS with 10TB allocation?

Why have an Expand Capacity on RAID5 if you can’t actually do it?