Short demonstration of raid10 with btrfs

Short demonstration of modern software raid options using btrfs. In this example raid10 is used to show what happens when a whole disc is lost. We use common btrfs commands to repare the raid10 architecture and as a result can see that no data is lost.

The demonstration shows all current filesystems btrfs filesystem show && lsblk. Then the partition is mounted by mounting any of the drives that are part of the raid. /dev/sdd till /dev/sdg are part of the raid10 configuration. In the mounted partition we see a 862 megabyte file. We override /dev/sdd with random bits dd if=/dev/urandom of=/dev/sdd. When we query btrfs to list the filesystems it shows the drive is missing. By mounting the drive with the -o degraded we can restore the partition. Even though one disc is missing we can still use it although is really unrecommended.

btrfs filesystem show
mount /dev/sdd /mnt
ls -lah /mnt
umount /mnt
dd if=/dev/urandom /dev/sdd
btrfs filesystem show
mount -o degraded /dev/sde /mnt
btrfs replace start 1 /dev/sdd /mnt
btrfs replace status /mnt
btrfs filesystem show

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