Linux – How to change the file system of a partition in a RAID 1

First, sorry if the question has already been asked and correctly answered, I did not find anything that satisfies me.

I rent a dedicated machine in a datacenter, the machine run with a Debian 10 and has two drives in RAID 1, there are 3 partitions: one for the boot, one for the swap and one for the rest.

The third (/dev/md2) uses the ext4 file system and I would like to use XFS instead.

I am not used to changing the filesystem and this is the first time I have a machine with RAID so I do not know how to do it.

This is a new installation so there is no risk of losing data.

I tried a mkfs.xfs /dev/md2 but it didn't work:

root@Debian-105-buster-64-minimal ~ # mkfs.xfs /dev/md2
mkfs.xfs: /dev/md2 contains a mounted filesystem

And I don't know how it should be unmount/mount due to the RAID.

Thank you in advance for the help.

The df -Th command :

root@Debian-105-buster-64-minimal ~ # df -Th
Filesystem     Type      Size  Used Avail Use% Mounted on
udev           devtmpfs   32G     0   32G   0% /dev
tmpfs          tmpfs     6.3G  516K  6.3G   1% /run
/dev/md2       ext4      437G  1.2G  413G   1% /
tmpfs          tmpfs      32G     0   32G   0% /dev/shm
tmpfs          tmpfs     5.0M     0  5.0M   0% /run/lock
tmpfs          tmpfs      32G     0   32G   0% /sys/fs/cgroup
/dev/md1       ext3      487M   53M  409M  12% /boot
tmpfs          tmpfs     6.3G     0  6.3G   0% /run/user/1000

the fdisk -l command :

root@Debian-105-buster-64-minimal ~ # fdisk -l
Disk /dev/nvme0n1: 477 GiB, 512110190592 bytes, 1000215216 sectors
Disk model: SAMSUNG MZVLB512HAJQ-00000
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x0289e0d1

Device         Boot    Start        End   Sectors   Size Id Type
/dev/nvme0n1p1          2048   67110911  67108864    32G fd Linux raid autodetect
/dev/nvme0n1p2      67110912   68159487   1048576   512M fd Linux raid autodetect
/dev/nvme0n1p3      68159488 1000213167 932053680 444.4G fd Linux raid autodetect


Disk /dev/nvme1n1: 477 GiB, 512110190592 bytes, 1000215216 sectors
Disk model: SAMSUNG MZVLB512HAJQ-00000
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0xbcb5c0d2

Device         Boot    Start        End   Sectors   Size Id Type
/dev/nvme1n1p1          2048   67110911  67108864    32G fd Linux raid autodetect
/dev/nvme1n1p2      67110912   68159487   1048576   512M fd Linux raid autodetect
/dev/nvme1n1p3      68159488 1000213167 932053680 444.4G fd Linux raid autodetect


Disk /dev/md1: 511 MiB, 535822336 bytes, 1046528 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/md0: 32 GiB, 34325135360 bytes, 67041280 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/md2: 444.3 GiB, 477076193280 bytes, 931789440 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes

The mdstat :

root@Debian-105-buster-64-minimal ~ # cat /proc/mdstat
Personalities : [raid1] [linear] [multipath] [raid0] [raid6] [raid5] [raid4] [raid10]
md2 : active raid1 nvme0n1p3[0] nvme1n1p3[1]
      465894720 blocks super 1.2 [2/2] [UU]
      bitmap: 0/4 pages [0KB], 65536KB chunk

md0 : active (auto-read-only) raid1 nvme0n1p1[0] nvme1n1p1[1]
      33520640 blocks super 1.2 [2/2] [UU]
        resync=PENDING

md1 : active raid1 nvme0n1p2[0] nvme1n1p2[1]
      523264 blocks super 1.2 [2/2] [UU]

unused devices: <none>