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OrakMoya

Member

Registered: 2019-09-22

Posts: 75

Some BTRFS subvolumes not mounted at boot.

Hello,

Some of my BTRFS subvolumes do not mount at boot, but mounts without a problem after boot by just running mount on the mount point.
These are my subvolumes (excluding all the snapshots):

ID 256 gen 23762 top level 5 path subvol-root
ID 257 gen 23762 top level 5 path subvol-var
ID 258 gen 23762 top level 5 path subvol-home
ID 286 gen 23759 top level 256 path subvol-root/.snapshots
ID 873 gen 23570 top level 5 path subvol-videos

The subvolumes that don't mount properly are subvol-videos (should mount at /home/orakmoya/Videos) and the top-level subvolume itself (should mount at /mnt/subvolumes). Both of them mount properly by just running:

 # mount /home/orakmoya/Videos
 # mount /mnt/subvolumes

This is my fstab:

# /dev/nvme0n1p3
UUID=6484b07b-140a-4399-bdf2-c8ce87735db7       /               btrfs           rw,relatime,ssd,subvolid=256,subvol=/subvol-root,compress-force=zstd:1,noatime,space_cache=v2,discard=async     0 0

# /dev/nvme0n1p1
UUID=2997-7822          /boot           vfat            rw,relatime,fmask=0022,dmask=0022,codepage=437,iocharset=ascii,shortname=mixed,utf8,errors=remount-ro   0 2

# /dev/nvme0n1p3
UUID=6484b07b-140a-4399-bdf2-c8ce87735db7       /var            btrfs           rw,relatime,ssd,subvolid=257,subvol=/subvol-var,noatime,space_cache=v2,discard=async    0 0

# /dev/nvme0n1p3
UUID=6484b07b-140a-4399-bdf2-c8ce87735db7       /home           btrfs           rw,relatime,ssd,subvolid=258,subvol=/subvol-home,compress-force=zstd:1,space_cache=v2,discard=async     0 0

# /dev/nvme0n1p3
UUID=6484b07b-140a-4399-bdf2-c8ce87735db7       /home/orakmoya/Videos           btrfs           rw,relatime,ssd,subvolid=873,subvol=/subvol-videos,compress-force=zstd:19,space_cache=v2,discard=async  0 0

# /dev/nvme0n1p3
UUID=6484b07b-140a-4399-bdf2-c8ce87735db7       /mnt/subvolumes         btrfs           rw,relatime,ssd,space_cache=v2,discard=async    0 0


# /dev/nvme0n1p2
UUID=f8af3027-8c45-476f-a6bf-cd234988e279       none            swap            defaults,pri=10         0 0

Last edited by OrakMoya (2022-01-15 09:39:34)

ua4000

Member

Registered: 2015-10-14

Posts: 562

Re: Some BTRFS subvolumes not mounted at boot.

I suspect a simple race-condition, e.g. /home/orakmoya/Videos depend on /home ...
Post/inspect your systemd for failed mount services.

Proposal, leave the "top" mount points as they are,
all others, which are depending on them set to NOT automount, but when needed, fstab options: noauto,x-systemd.automount

Another idea is to simplify your setup,
btrfs subvolumes are a good idea, but you can put them already in the right structure on top with nesting - no need for a plain setup:

/
  /var 
  /home
            /orakmoya/Videos

 
So you need to mount only "/" but you have them all in different subvolumes.
Reorganising can be done fast and without risk with the "snapshot" function, e.g.

btrfs subvolume snapshot /mnt/home /mnt/wherever/home