How to upgrade PR4100 from 8TB to 16 or more without loosing data


Hi there I’m in a jam right now, I would like to know how can I upgrade my WD PR4100 I have 4 2TB drives right now i want to upgrade from 8TB to 16 or more safely without losing data, as I don’t have a backup and I’m running out of space.
My current Storage is on RAID 5 and I have Auto-Rebuild off.

Thanks in advance looking forward to your help


Hi talsudairy,

The drive cannot be upgraded without backing up the data. Upgrading the drives will need to have the raid rebuilt and that is data destructive. In order to upgrade the size if the drives in the RAID array you would need to backup the NAS then change the drives and configure the RAID and then restore the backup to the new RAID.


Thanks James, I think I figured it I went to Storage/RAID then I clicked on Chainge RAID Mode and on that page I clicked on Expand RAID, the upgrading and expansion started yesterday afternoon each drive takes about 4 hours plus to finish, as soon as the drive is done it asks to put in the next one and so on.
And the cool thing is, I am able to use the server as if all is ok and Plex is working great.

Thanks for replying to my question.


Everything went smoothly all my data is intact and my PR4100 has been upgraded from 8TB to 24TB it took about 48 hrs for it to happen but all is good.
I hope this can help anyone who faces the same issue I had


Thanks for sharing your progress.
I did see the 64bit flag on the RAID but I thought e2fsprogs was outdated. I guess they included the necessary patches.


You’re welcome Tfi


Deat Talsudairy,
Thanks for sharing.
I own a pretty much filled WD Book Duo 12TB (2x6TB in RAID1) and want to upgrade to a WD PR4100 empty and buy additional two 6TB RED NAS HDD.
I wonder if it would be possible to insert the two almost filled HDD from the WD Book Duo into the PR4100 and expand the RAID 1 on the additional 2x6TB.
Any suggestions?



RAID1 is mirror mode. You would end up with 4x copies of a single disk.
You should create a RAID5 volume with 3 disks on the PR4100, copy all data from the Book Duo (with 1 disk) to the new Volume on the PR4100 and then extend the volume from 3 to 4 disks.

Or you make a JBOD volume with 2 disk on the PR4100, copy all data, then plug 2 extra disks (they will be formatted in all cases).


Great suggestion! WILCO!
THX a lot