RAID Group 1 status is 'degraded' and disk 1 status is 'not member'

[bobbymules]

Hi.

PROBLEM
I have a TS-453B (5.0.0.1932) with the error:
"Message: [Storage & Snapshots] RAID group "1" is degraded. Volume: backups."
- RAID Group 1 status is 'degraded' and disk 1 status is 'not member'

OBSERVATIONS
- disk 1 & 2 are part of RAID group 1 'backups' with 3TB capacity
- confirmed both disks in good health via 'storage & snapshots > storage > disks/VJBOD'
- FYI both disks used to be 3TB, they have both been replaced with 4TB but RAID Group 1 still showing as 3TB

TROUBLESHOOTING
- when opening 'storage & snapshots' app and goto storage/snapshots, a dialogue box comes up to 'rebuild RAID group' for RAID group 1, I click 'rebuild' but nothing happens, no task is added, no change
- tried swapping out disk 1 with fresh disk but doesn't change status of 'not member', no change
- tried 'check file system', no change
- 'storage & snapshots > storage > storage/snapshots > select 'backups', click manage > click manage > rebuild RAID group > there are no disks to select

This RAID group is my system group. I don't know what else to do. The only option I see is to 'remove' but don't know what this does.

Any ideas? Currently running on a single disk for this RAID group.

Thanks.

[bobbymules]

added screenshots

[dolbyman]

clear the problematic disk and try to hotswap it back in

after that follow the process to expand your volume to 4TB (3.6)

[bobbymules]

thanks @dolbyman - I raised a support case and got remote support
the engineer somehow removed the problematic disk and now it's a single disk / no raid > I can migrate this from single to raid 1 using manage > migrate?

questions:
1) how do you 'clear the problematic disk'? Is there a command? I tried replacing with multiple physical disks with no change. It's done now anyway but curious.
2) 'follow the process to expand your volume' - what is this? The 'Replace Disks One by One' option in the GUI?

I appreciate your help and input

[dolbyman]

1) externally via usb dock and a different system

2) check the user manual on how to expand volumes (yes the one by one interface)

[hybraq]

Hi, I'm having the same problem on a same QNAP NAS (TS-453b), new disk, WD RED PRO 4TB, wanted to swap the previous 5TB because all the other 3 disks were 4TB so I was wasting a 1TB from the 5TB disk, did a "Replace disk one by one" and hot removed the 5TB. then inserted the new 4TB and now RAID 5 says degraded and the new disk is "No member".
Anybody got a solution for this?
Thanks

[bobbymules]

hi hybraq,
my suggestion would be to log a ticket: https://service.qnap.com/en-us/user/create-ticket
I wanted to solve the issue myself but then the heldesk ended up resolving it for me via remote access. Only thing I had to do was change my user password to a temp one then change back after their work was completed.

these we my personal notes:
## 26/02/22
helpdesk removed disk 1 from group, changed from raid 1 to single
I am unable to migrate from single to raid 1, error 'checking disk status failed'

## 28/02/22
<engineer> magically fixed it:
x removed faulty member
x expanded single to raid 1
asked for commands / process but unlikely to get