Is it Possible to detach a disk from a Raid 6 Volume

English Storage
1

Hi, Please be patient and understanding. I have search for the information, but can not seem to find what I want. I have a TS-853A(firmware QTS 5.2.5.3145) with 8 disks in there.
They are the WD Red Plus WD40EFRX 3.5" 4TB 5400rpm drives, all of them are the same. I am not sure what I was thinking back then, to have 8 x 4TB drives in Raid 6. I thought I would use all the storage space, but in fact I have only used 6.25TB of storage out of the 21TB.

That being said, it has been 8 years since I bought the beast and the Drives are starting to show their age. I have just had the first notification that there is a bad sector on disk 4. I plan on purchasing a new 4TB drive today to replace it.
However I have a couple of Questions:
Instead of having all 8 slots occupied, I was thinking of having just 4 drives. Say 4 x 8TB drive in RAID 6(I understand that 2 drives are lost to redundancy for Raid 6)
Can this be done without losing any data?

Also if I go to Storage and Volume, and then select the manage Volume option, there is an option to replace disk one by one, which is great, But I do not want to replace all disks.
How to I remove the disks from the volume without losing any data. Is this possible?

2

No you cannot remove any disks from a RAID without it going into degraded mode. Removing two disks from RAID6 would put it into degraded mode without redundancy and any further disk failure or removal would kill the RAID

If you are afraid of losing data, make sure you create or rethink your backup strategy

3

Hi. Thanks for the reply. I shall do another back up to my Synology NAS and then proceed to remove all disks from the QNAP device and use 8TB drives.
I suspected this was the case, but just had to be sure.

4

You can do that…it will be a fresh install as the OS is on the drives

5

You can SSH into the NAS and remove drives from the array and have it rebuild.
But you need to do it one at a time. So it would be 4 COMPLETE rebuilds.

You CAN do this. You SHOULD NOT do this.

Buying new drives and starting over is the correct choice in this case.