You won’t be able to expand an existing volume to a volume over 16TB.
The tools to resize EXT3 file systems are outdated (e2fsprogs and resize2fs)… you need at least v1.43
See here
You are able to
- create larger volumes from scratch
- rebuild an existing volume (after replacing 1 disk)
You may not be able to
- expand existing volumes over 16TB
Some time ago I tried to go from RAID5 4x4 TB to 4x8 TB and the rebuild was successful but I couldn’t expand my capacity. To top it off, my 8 TB drives were stuck as you can’t go back and rebuild with the 4 TB disks…
I hope that the support team can confirm this.
The link above does provide instructions to bypass this limitation but it’s quite challenging to do this on the PR4100.
I’d install entware on a USB flash drive with a recent version of e2fsprogs (it has v1.43.5) or use git to get the latest version.
Then find a way to unmount your RAID5 volume (stop all services first) … and follow the rest of the guide.
Disclaimer: this is quite advanced stuff, you may lose your data. Do it at your own risk.
Rebuilds take almost 24h for a single 4 TB disk. Use a backup UPS.
EDIT: I’ve heard reports that WD has patched their version of e2fsprogs so you can expand beyond 16TB.
