Re: Btrfs failing to make incremental backups

[David Sardari <d@duxsco.de>]

I understand. Next time I write everything in the mail body.

I deleted the snapshot on the destination side. So, I had to do again
just now resulting in same problem:

   btrfs send -p | \
       "${SRC}/@2021-10-30-095620_files" \
       "${DST}/@2021-10-30-100526_files" | \
       btrfs receive "${DST}/"; echo $status; sync
   At subvol /mnt/backup/src/@00_snapshot_hourly/@2021-10-30-100526_files
   At snapshot @2021-10-30-100526_files
   0

The parent snapshot:

   bash-5.1# btrfs subvolume show "${SRC}/@2021-10-30-095620_files"
   WARNING: the subvolume is read-write and has received_uuid set,
   	 don't use it for incremental send. Please see section
   	 'SUBVOLUME FLAGS' in manual page btrfs-subvolume for
   	 further information.
   @00_snapshot_hourly/@2021-10-30-095620_files
   	Name: 			@2021-10-30-095620_files
   	UUID: 			c4914d2e-b1f7-134e-984f-bf686f8d919b
   	Parent UUID: 		537c7db2-05da-6546-9092-89f873d7276a
   	Received UUID: 		7eb8ade9-0234-474c-b3c6-
   3b439bb51aa4
   	Creation time: 		2021-10-30 11:56:20 +0200
   	Subvolume ID: 		5914
   	Generation: 		319458
   	Gen at creation: 	319458
   	Parent ID: 		5855
   	Top level ID: 		5855
   	Flags: 			readonly
   	Send transid: 		14924
   	Send time: 		2021-10-30 11:56:20 +0200
   	Receive transid: 	1276
   	Receive time: 		2020-10-30 23:44:11 +0100
   	Snapshot(s):

Snapshot that needs to be sent:

   bash-5.1# btrfs subvolume show "${SRC}/@2021-10-30-100526_files"
   WARNING: the subvolume is read-write and has received_uuid set,
   	 don't use it for incremental send. Please see section
   	 'SUBVOLUME FLAGS' in manual page btrfs-subvolume for
   	 further information.
   @00_snapshot_hourly/@2021-10-30-100526_files
   	Name: 			@2021-10-30-100526_files
   	UUID: 			74c54234-20b3-7d4c-9dd8-ebb919d2e876
   	Parent UUID: 		537c7db2-05da-6546-9092-89f873d7276a
   	Received UUID: 		7eb8ade9-0234-474c-b3c6-
   3b439bb51aa4
   	Creation time: 		2021-10-30 12:05:26 +0200
   	Subvolume ID: 		5920
   	Generation: 		319481
   	Gen at creation: 	319481
   	Parent ID: 		5855
   	Top level ID: 		5855
   	Flags: 			readonly
   	Send transid: 		14924
   	Send time: 		2021-10-30 12:05:26 +0200
   	Receive transid: 	1276
   	Receive time: 		2020-10-30 23:44:11 +0100
   	Snapshot(s):


Resulting snapshot on the destination side:

   bash-5.1# btrfs subvolume show "${DST}/@2021-10-30-100526_files"
   WARNING: the subvolume is read-write and has received_uuid set,
   	 don't use it for incremental send. Please see section
   	 'SUBVOLUME FLAGS' in manual page btrfs-subvolume for
   	 further information.
   @00_snapshot_hourly/@2021-10-30-100526_files
   	Name: 			@2021-10-30-100526_files
   	UUID: 			4a97faed-5852-e140-a6ec-4eaac6ab4863
   	Parent UUID: 		e04d86db-293a-cc44-a226-059677aa6e11
   	Received UUID: 		7eb8ade9-0234-474c-b3c6-
   3b439bb51aa4
   	Creation time: 		2021-10-30 15:54:32 +0200
   	Subvolume ID: 		3300
   	Generation: 		1146
   	Gen at creation: 	1146
   	Parent ID: 		1988
   	Top level ID: 		1988
   	Flags: 			readonly
   	Send transid: 		319434
   	Send time: 		2021-10-30 15:54:32 +0200
   	Receive transid: 	1147
   	Receive time: 		2021-10-30 15:54:32 +0200
   	Snapshot(s):

-- 
My GnuPG public key:
gpg --auto-key-locate clear,dane --locate-external-key d@duxsco.de



On Sat, 2021-10-30 at 16:38 +0300, Andrei Borzenkov wrote:
> This makes it impossible to comment on your description or logs inline.
> 
> Anyway, the usual primary suspect is duplicated received UUID. Show
> "btrfs subvolume show snapshot" on both source and destination systems
> for each involved snapshot.