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gabx

Member

From: Geneva, Switzerland

Registered: 2011-11-20

Posts: 179

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btrfs snapshots: created snapshots are empty

I want to set up a backup mechanism with btrbk package. Here are my settings:

/etc/fstab

LABEL=magnolia         /btrfs     	                                rw,noatime,compress=zstd:3,discard=async,ssd,space_cache,commit=120,subvolid=256,subvol=/@	      0 0
LABEL=magnolia		/btrbk_pool	btrfs		noatime,compress=zstd:3,discard=async,ssd,space_cache,commit=120,subvolid=5			                       0 0
LABEL=magnolia        /home     	btrfs     	       rw,noatime,compress=zstd:3,discard=async,ssd,space_cache,commit=120,subvolid=257,subvol=/@home	0 0
....
-------------------------------------------------------------
/etc/btrbk/btrbk.conf

timestamp_format        long
snapshot_preserve_min   18h
snapshot_preserve       48h

snapshot_dir btrbk_snapshots

volume /btrbk_pool
  subvolume @home
----------------------------------------
[root@magnolia gabx]# ls -al /btrbk_pool/
total 16
drwxr-xr-x 1 root root  88 May 16 13:30 .
drwxr-xr-x 1 root root 196 May 16 13:52 ..
drwxr-xr-x 1 root root 196 May 16 13:52 @
drwxr-xr-x 1 root root 112 May 16 15:06 btrbk_snapshots
drwxr-xr-x 1 root root  32 May 15 18:53 @home

[root@magnolia gabx]# btrfs sub l /btrbk_pool/
ID 256 gen 1111 top level 5 path @
ID 257 gen 1111 top level 5 path @home
ID 263 gen 1122 top level 257 path @home/gabx.homedir  <--- created by systemd.homed

Running dry btrbk leaves me with no error, and running btrbk created the expected snapshot:

[root@magnolia gabx]# ls -al /btrbk_pool/btrbk_snapshots/
total 16
drwxr-xr-x 1 root root 112 May 16 15:06 .
drwxr-xr-x 1 root root  88 May 16 13:30 ..
drwxr-xr-x 1 root root  32 May 15 18:53 @home.20220516T1336
[root@magnolia gabx]# ls -al /btrbk_pool/btrbk_snapshots/@home.20220516T1336
total 0
drwxr-xr-x 1 root root  32 May 15 18:53 .
drwxr-xr-x 1 root root 112 May 16 15:06 ..
drwx------ 1 root root   0 May 15 18:53 gabx
drwxr-xr-x 1 root root   0 May 16 15:08 gabx.homedir

Unfortunately, both gabx and gabx.homedir are empty.
What am I missing?
Thank you for help

NOTE
Even without running btrbk a simple snapshot command leaves me with empty folders:

[root@magnolia gabx]# btrfs sub snapshot /home /btrbk_pool/
Create a snapshot of '/home' in '/btrbk_pool//home'
[root@magnolia gabx]# ls -al /btrbk_pool/home/
total 0
drwxr-xr-x 1 root root 32 May 15 18:53 .
drwxr-xr-x 1 root root 38 May 17 16:29 ..
drwx------ 1 root root  0 May 15 18:53 gabx  <--- empty
drwxr-xr-x 1 root root  0 May 17 16:29 gabx.homedir  <--- empty

Last edited by gabx (2022-05-17 15:03:39)

ua4000

Member

Registered: 2015-10-14

Posts: 492

Re: btrfs snapshots: created snapshots are empty

Are gabx and gabx.homedir mountponts or btrfs subvolumes ?
A snapshot with btrfs does contain only the real existing data, no subvolumes are included, a btrfs snapshot is not recursive.
Is this your case ?