RAID1 to single disk

English Storage
1

Hi! I’m trying to change NVME RAID1 to single disk configuration according to this: RAID1 to single disk - QNAP NAS Community Forum but I’m stuck at the “mdadm --grow /dev/md1 --raid-devices=1 --force” command to which I only get back: “mdadm: failed to set raid disks”.

Any idea why it doesn’t work anymore?

2

What is the NAS model and firmware used ?

3

TS-264 with QTS 5.2.6.3195

4

And it’s for sure running QTS and not QuTS ? (because the x64 devices support both)

QuTS has the same build here

5

I am sure

6

and you are logged in as ‘admin’ ? (some of these commands will not run via sudo)

7

Yes, factory admin and tried sudo as well

8

Can you post the result of

mdadm --query --datail /dev/md1

9 
/dev/md1:
        Version : 1.0
  Creation Time : Mon Jul  7 18:36:49 2025
     Raid Level : raid1
     Array Size : 1904688640 (1816.45 GiB 1950.40 GB)
  Used Dev Size : 1904688640 (1816.45 GiB 1950.40 GB)
   Raid Devices : 2
  Total Devices : 1
    Persistence : Superblock is persistent

  Intent Bitmap : Internal (in-memory)

    Update Time : Thu Aug 21 00:14:18 2025
          State : clean, degraded 
 Active Devices : 1
Working Devices : 1
 Failed Devices : 0
  Spare Devices : 0

           Name : 1
           UUID : 619a12d3:d90e08d2:1ac4973c:00a07a48
         Events : 6211

    Number   Major   Minor   RaidDevice State
       0     259        3        0      active sync   /dev/nvme0n1p3
       2       0        0        2      removed```
10

Have you tried removing the bitmap first ?

11

How’s that done?

12

It should work via GUI, but if it does not work on a degraded RAID you can try

mdadm --grow --bitmap=none /dev/md1

13

Seems like that was it! Thx!

Since I’m here…next step in the guide is to edit raid.conf, most of the stuf is clear, but I’m not sure why and what to change the “chunkSize” to as I never had these disks configured as single disks. Do you have any wisdom to share about that before I mess something up?

14

Never fiddled around in there, try the values advised in the old forum and see.

Chunk sizes would make sense on striped or parity RAIDs (0/5/6/10) no idea what they would be/do on a block copy RAID1.

15

Why not just backup the data, reconfigure, restore the data? You do have backups right?

16

That is my way of reasoning, why any chunk size for single drive at all? Ok I’ll try and see. Wish me luck

17

Because this is like 100 times faster? Besides my backups are off-site and my internet is like 50Mbps download, so no way I’m doing it that way. The spare I took out of the original RAID1 is my on-site backup right now so I have some space to experiment.

18

Faster?

Back up to a 2TB USB drive, reconfigure, restore, surely faster than the 17 hours you’ve been posting in this thread. Mangling a disk configuration manually may result in you having to restore your data anyway. RAID is not a backup. Splitting a RAID configuration opens you to all kinds of potential issues and data loss.

Your data, your time, just my opinion.

19

Did I mention it’s OS drive? So yeah, 100 times faster…obviously I didn’t spend 17hrs on this, maybe 1 hr, I need to sleep sometimes too :wink:

20

The OS would be on all internal drives (so if you stick another drive into the NAS, the OS will be on that too), I guess you meant ‘drive with the system volume’