Expand RAID 5 Array on PR4100

I have a WD PR4100 My Cloud on firmware 2.31.183 with 4 x 6TB drives configured as RAID 5 (giving me ~18 TB of space) with ~2.36 TB free.

I need to expand the RAID volume and want to add 2 more 6TB drives in an external USB 3 enclosure. I initialized the disks as GPT by connecting them to a PC, and formatted as NTFS without assigning a drive letter.

When I attach the drive enclosure to the PR4100, I only see 1 disk under USB connections (not the 2 that are inserted) and no way to add them to the existing volume.

How do I go about increasing the storage capacity of the PR4100?


See the dedicated subforum for the PR Series where people more familiar with that device may be able to assist.


This subforum, My Cloud, generally discusses the single bay My Cloud model which is different than the PR series.