I have (another) Pro 6 with bays populated with 3tb WD Reds in Raid5. Or so I thought.
I purchased a 6tb hard drive to put in the 6th bay and create a separate volume for backups, DR for another NAS, etc...
The moment I added the 6th disk, the Pro6 immediately added to the data volume and started building that drive. Once I noticed it, I yanked it out, and I noticed the XRAID indicator on data volume. I switched to FlexRaid, and it started resyncing.
Meanwhile, I added the 6th disk again, I formated it and I created a new JBOD volume out of it, aptly called ‘SIX’. Twisted sense of humor. After a few minutes, Six was online and well. I created some shares, and even put the OneDrive app to dump data on a newly created share on Six.
This morning, volume data (4x3tb) finished rebuilding, all looks fine, but it says degraded.
So, you had XRAID turned on and added a disk to the NAS which will prompt an expansion of the raid. XRAID will immediately expand your raid5 to 5 disks, rather than 4. Now, that you pulled the 5th disk, you raid is degraded as it expects 5 disks.
To go back to 4 disks from that is not simple. You can possibly shrink the raid via mdadm but that might be a bad idea to mess with.
You have a spare bay... maybe get a disk for the raid5 to make it redundant and a 5xdisk raid instead of 4. Do you have plans for that spare bay?
Alternatively, factory reset and then create your volumes again...
The whole idea was to have a non-redundant scratch disk, independent from the data one. Not only it is more cost/space efficient, but also makes the backups independent from any hickups... such as now. 🙂
By first hand experience and reading through the forums, the most common solution to problems is “factory reset and restore your backups”. Don’t get me wrong, I am very grateful to this community and an active participant. But having all bays in a single volume is a mistake that I will not repeat.
And yes, the array was 4x3TB, and the scratch disk was a new 6TB disk, from a different brand/geometry/series.
