My experience to grow an existing BTRFS pool of disk

raulfg3 · Apr 15th 2023

I have a BTRFS Pool of 4 disk not redundant because I have a Backup on other location and want to grow it.

I only need to purchase a new 16TB disk:

Then add it to my NAS and reboot NAS, the disk was recognized by OMV WebGI. then from CLI/Shell I add the /dev/sdg disk and all are work now

No need to balance because my exiting pool is not a RAID or heavy full.

more info on: https://wiki.tnonline.net/w/Bt…ding_and_removing_devices

only annoing thing is that do not appear to be BTRFS formated and part of BPool, so perhaps I do something wrog, anyone can help me to know if ineed to do someting more to add disk as part of BPool:

Perhaps format first like a BTRFS disk and then add it to thr BPool?

more info:

Code

root@bnas:~# btrfs filesystem show
Label: 'BPool'  uuid: b8a4b42c-8db1-4bf8-a0fa-c1ecb80f3769
Total devices 5 FS bytes used 32.84TiB
devid    1 size 9.10TiB used 8.24TiB path /dev/sdf
devid    2 size 9.10TiB used 8.24TiB path /dev/sdd
devid    3 size 9.10TiB used 8.24TiB path /dev/sdc
devid    4 size 9.10TiB used 8.24TiB path /dev/sde
devid    5 size 14.55TiB used 0.00B path /dev/sdg


root@bnas:~#

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perhaps balance is recomended?

raulfg3 · Apr 17th 2023

ok, e2label do the magic, but appears to fail:

Code

root@bnas:~# lsblk -f
NAME   FSTYPE FSVER LABEL UUID                                 FSAVAIL FSUSE% MOUNTPOINT
sda
├─sda1 ext4   1.0         865bd228-21bc-421f-b80a-b714215923ce  168,8G    10% /
├─sda2
└─sda5 swap   1           78c8b698-8d6f-4337-824c-50cfbdf580c6                [SWAP]
sdb
└─sdb1 ext4   1.0   DATA  6f38f974-7aec-452a-815d-9101878af2e1  847,8G     7% /srv/dev-disk-by-uuid-6f38f974-7ae
sdc    btrfs        BPool b8a4b42c-8db1-4bf8-a0fa-c1ecb80f3769
sdd    btrfs        BPool b8a4b42c-8db1-4bf8-a0fa-c1ecb80f3769
sde    btrfs        BPool b8a4b42c-8db1-4bf8-a0fa-c1ecb80f3769
sdf    btrfs        BPool b8a4b42c-8db1-4bf8-a0fa-c1ecb80f3769   18,1T    65% /srv/dev-disk-by-uuid-b8a4b42c-8db
sdg
root@bnas:~# e2label
Usage: e2label device [newlabel]
root@bnas:~# e2label /dev/sdg BPool
e2label: Bad magic number in super-block while trying to open /dev/sdg
/dev/sdg contains a btrfs file system labelled 'BPool'
root@bnas:~# lsblk -f
NAME   FSTYPE FSVER LABEL UUID                                 FSAVAIL FSUSE% MOUNTPOINT
sda
├─sda1 ext4   1.0         865bd228-21bc-421f-b80a-b714215923ce  168,8G    10% /
├─sda2
└─sda5 swap   1           78c8b698-8d6f-4337-824c-50cfbdf580c6                [SWAP]
sdb
└─sdb1 ext4   1.0   DATA  6f38f974-7aec-452a-815d-9101878af2e1  847,8G     7% /srv/dev-disk-by-uuid-6f38f974-7ae
sdc    btrfs        BPool b8a4b42c-8db1-4bf8-a0fa-c1ecb80f3769
sdd    btrfs        BPool b8a4b42c-8db1-4bf8-a0fa-c1ecb80f3769
sde    btrfs        BPool b8a4b42c-8db1-4bf8-a0fa-c1ecb80f3769
sdf    btrfs        BPool b8a4b42c-8db1-4bf8-a0fa-c1ecb80f3769   18,1T    65% /srv/dev-disk-by-uuid-b8a4b42c-8db
sdg    btrfs        BPool b8a4b42c-8db1-4bf8-a0fa-c1ecb80f3769
root@bnas:~#

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and for info pourpouse, actual Disk temp (3 or 4 degrees plus):

raulfg3 · Apr 18th 2023

At the end I read links and conclude that I need to balance pool, but not sure what is the best aproach.

some help will be apreciated.

btrfs-balance(8) - Linux manual page

Balance — BTRFS documentation

macom · Apr 18th 2023

I use btrfsmaintenance. They have this statement regarding parameters for balance

Quote

Versions up to 0.4.2 had usage filter set up to 50% for data and up to 30% for
metadata. Based on user feedback, the numbers have been reduced to 10% (data)
and 5% (metadata).

GitHub - kdave/btrfsmaintenance: Scripts for btrfs maintenance tasks like periodic scrub, balance, trim or defrag on selected mountpoints or directories.

Scripts for btrfs maintenance tasks like periodic scrub, balance, trim or defrag on selected mountpoints or directories. - GitHub - kdave/btrfsmaintenance:…

github.com

btrfs filesystem balance start -dusage=10 -musage=5 <mountpoint>

andrzejls · Apr 18th 2023

Quote from raulfg3

ok, e2label do the magic, but appears to fail:

e2label only works on EXT* formats not on BTRFS.

raulfg3 · Apr 19th 2023

Quote from andrzejls

e2label only works on EXT* formats not on BTRFS.

I know, but see the sdg line after:

and before trying to apply e2label:

Code

root@bnas:~# e2label /dev/sdg BPool
e2label: Bad magic number in super-block while trying to open /dev/sdg
/dev/sdg contains a btrfs file system labelled 'BPool'
root@bnas:~# lsblk -f
NAME   FSTYPE FSVER LABEL UUID                                 FSAVAIL FSUSE% MOUNTPOINT
sda
├─sda1 ext4   1.0         865bd228-21bc-421f-b80a-b714215923ce  168,8G    10% /
├─sda2
└─sda5 swap   1           78c8b698-8d6f-4337-824c-50cfbdf580c6                [SWAP]
sdb
└─sdb1 ext4   1.0   DATA  6f38f974-7aec-452a-815d-9101878af2e1  847,8G     7% /srv/dev-disk-by-uuid-6f38f974-7ae
sdc    btrfs        BPool b8a4b42c-8db1-4bf8-a0fa-c1ecb80f3769
sdd    btrfs        BPool b8a4b42c-8db1-4bf8-a0fa-c1ecb80f3769
sde    btrfs        BPool b8a4b42c-8db1-4bf8-a0fa-c1ecb80f3769
sdf    btrfs        BPool b8a4b42c-8db1-4bf8-a0fa-c1ecb80f3769   18,1T    65% /srv/dev-disk-by-uuid-b8a4b42c-8db
sdg    btrfs        BPool b8a4b42c-8db1-4bf8-a0fa-c1ecb80f3769
root@bnas:~#

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ryecoaaron · Apr 19th 2023

That just tells you that e2label is smart enough to know there is already a filesystem labeled BPool but obviously it won't work on btrfs.

macom · Apr 19th 2023

To change label of btrfs filesystem

btrfs filesystem label <mountpoint> <newlabel>

btrfs-filesystem(8) — BTRFS documentation

My experience to grow an existing BTRFS pool of disk

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