How to Create and Manage Btrfs File System in Linux - Part 3

Mounting Btrfs Subvolume

19. First to know the ID of subvolumes list the subvolumes using below command.

# btrfs subvolume list /mnt/tecmint_btrfs1/

20. Then to mount the subvolumes we should umount the parent volume (our mount) /mnt/tecmint_btrfs1/.

# umount /mnt/tecmint_btrfs1/

21. Then mount the subvolume using it’s ID which we get from listing the subvolumes in above step.

# mount -o subvolid=272 /dev/tecmint_vg/tecmint_lv1 /mnt/tecmint_btrfs1/

This will mount the subvol1 using it’s ID to /mnt/tecmint_btrfs1/. Just list the mount point and check.

If we need to make our subvolume default we can use the following command.

# btrfs subvolume set-default 272 /mnt/tecmint_btrfs1/

22. To list the default subvolume we can use the following command.

# btrfs subvolume get-default /mnt/tecmint_btrfs1/

Mounting Btrfs Subvolume

Here I have listed the subvolume1 which I have mounted, Before while listing the mount point we have seen subvol1 & subvol2 inside the mount point /mnt/tecmint_btrfs1/, but here now i have mounted the subvol1 in /mnt/tecmint_btrfs1/ and we can see the files which we have before.

Confirm Btrfs Subvolume Creating Snapshots

23. To create a snapshot of source we can use below command.

# btrfs subvolume snapshot /source /destination

Here I want to take a snapshot of /mnt/tecmint_btrfs1/ to same location.

# btrfs subvolume snapshot /mnt/tecmint_btrfs1/ /mnt/tecmint_btrfs1/

While listing we can get the snapshot in same location as shown in the below image.

Create Btrfs Snapshots

24. In above steps I have not given a name for snapshot because of that we get the same name while creating a snapshot inside /mnt/tecmint_btrfs1/. Let we try to create a snapshot with snap_tec into /mnt/tecmint_btrfs1/.

# btrfs subvolume snapshot /mnt/tecmint_btrfs1/ /mnt/tecmint_btrfs1/snap_tec/
# ls -l /mnt/tecmint_btrfs1/snap_tec/tecmint_btrfs1/

Name Btrfs Snapshots

25. In above snapshots we can read and write any contents, If we need to create a read-only snapshot we can use -r option while we create a snapshot as shown below.

# btrfs subvolume snapshot -r /mnt/tecmint_btrfs1/ /mnt/tecmint_btrfs1/snap_readonly

Create Readonly Btrfs Snapshots Permanent Btrfs Mounting

26. Permanent mounting will be done using fstab entry. Open fstab file using your choice of editor.

# vi /etc/fstab

Next, add the following line to it. save and quit the file.

/dev/tecmint_vg/tecmint_lv1 /mnt/tecmint_btrfs1/ btrfs defaults 0 0

Permanent Btrfs Mounting

27. After mounting, verify whether mount are working after exiting from fstab.

# mount -a

To know more about Btrfs use manual.

# man btrfs

That’s it for now, Here we have seen how to setup brtfs file-system in Linux.

Conclusion

Btrfs file-system are still under experimental (testing) not into production, but soon it will be in production. Hope this article help you to know about the btrfs file-system. Let us know from your side through firing some comments below.

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