mjhjmtu

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

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.