Remove a disk from RAID1 without reinstalling system

Question

I have a remote server with 2 disks (2000 GB each) connected using software RAID1. Can I somehow disconnect the second disk from RAID and use it independently for storage without reinstalling system (Ubuntu) and keeping the data on the first disk?

cat /proc/mdstat:

Personalities : [raid1] [linear] [multipath] [raid0] [raid6] [raid5] [raid4] [raid10]
md0 : active raid1 sdb2[1] sda2[0]
  499392 blocks super 1.2 [2/2] [UU]

md1 : active raid1 sda3[0] sdb3[1]
  7996416 blocks super 1.2 [2/2] [UU]

md2 : active raid1 sda4[0] sdb4[1]
  1944881152 blocks super 1.2 [2/2] [UU]
  bitmap: 1/15 pages [4KB], 65536KB chunk

fdisk -l:

Disk /dev/sda: 1.8 TiB, 2000398934016 bytes, 3907029168 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: gpt
Disk identifier: 83BCC898-32B3-432D-B4E3-87B3995B386C

Device        Start        End    Sectors  Size Type
/dev/sda1      2048       4095       2048    1M BIOS boot
/dev/sda2      4096    1003519     999424  488M Linux RAID
/dev/sda3   1003520   17004543   16001024  7.6G Linux RAID
/dev/sda4  17004544 3907028991 3890024448  1.8T Linux RAID


Disk /dev/sdb: 1.8 TiB, 2000398934016 bytes, 3907029168 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: gpt
Disk identifier: A0DBD375-0E50-4C5A-A7A7-9584D2BF8950

Device        Start        End    Sectors  Size Type
/dev/sdb1      2048       4095       2048    1M BIOS boot
/dev/sdb2      4096    1003519     999424  488M Linux RAID
/dev/sdb3   1003520   17004543   16001024  7.6G Linux RAID
/dev/sdb4  17004544 3907028991 3890024448  1.8T Linux RAID


Disk /dev/md2: 1.8 TiB, 1991558299648 bytes, 3889762304 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes


Disk /dev/md1: 7.6 GiB, 8188329984 bytes, 15992832 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes


Disk /dev/md0: 487.7 MiB, 511377408 bytes, 998784 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes

score 0 · Answer 1 · answered May 03 '18 at 03:51

Technically, the removal of a disk from RAID 1 would count as a failed drive. It would continue functioning, but in a "degraded" state. It is theoretically possible, however, a bad idea in practice. Your best bet is to copy the files elsewhere if you can, even doing a drive clone.

If you can't do a drive clone to a spare hard drive, pull one, format it, duplicate files, use that as the main.

But please, back up your files, and don't assume the word of someone on the internet is law.

On the flipside, something something HW RAID ftw.

Remove a disk from RAID1 without reinstalling system

1 Answers1