incremental not working

[traxanos]

Hi

have some problems. i create snapshots with btrfs-snp:

Subvolume                                                         Total  Exclusive  ID
─────────────────────────────────────────────────────────────────────────────────────────
.snapshots/sync_2022-04-01_110631                               6.19TiB    5.45GiB  6893
.snapshots/sync_2022-04-01_110637                               6.18TiB  256.00KiB  6894
.snapshots/sync_2022-04-02_121818                               6.91TiB   92.39GiB  7958
.snapshots/sync_2022-04-03_084334                               6.93TiB    2.37MiB  8243
─────────────────────────────────────────────────────────────────────────────────────────
Total exclusive data                                                           97.85GiB

now i start btrfs-sync

* Check source
* Check destination
* Synchronizing '/backups/.snapshots/sync_2022-04-01_110631'...
time elapsed [18:07:22] | rate [94,8MiB/s] | total size [5,90TiB]TiB]
* Synchronizing '/backups/.snapshots/sync_2022-04-01_110637' using seed '/backups/.snapshots/sync_2022-04-01_110631'...
time elapsed [0:02:55] | rate [93,7MiB/s] | total size [16,1GiB]
* Synchronizing '/backups/.snapshots/sync_2022-04-02_121818' using seed '/backups/.snapshots/sync_2022-04-01_110637'...
time elapsed [3:09:14] | rate [ 105MiB/s] | total size [1,03TiB]

first and second snapshot with 5,90TiB and 16,1GiB looks good. whereby the second snapshot was in my opinion also too large. 256KiB result in 16,1 GiB. the third snapshot has only 100GiB exclusive data, but the sync is still transfer and it now schon bigger 1TiB.

and du you now why the snapshot size is different between the servers?

Subvolume                                                         Total  Exclusive  ID
─────────────────────────────────────────────────────────────────────────────────────────
sync_2022-04-01_110631                                          5.88TiB    5.60GiB  457
sync_2022-04-01_110637                                          5.89TiB   92.58MiB  6521
sync_2022-04-02_121818                                          6.66TiB    1.03TiB  6532
─────────────────────────────────────────────────────────────────────────────────────────
Total exclusive data                                                            1.03TiB

[traxanos]

so sync is done. but the sync data are wrong!

Local (Original):

5,9T    sync_2022-04-01_110637
6,4T    sync_2022-04-02_121818
6,1T    sync_2022-04-03_084334

Remote

5,9T	sync_2022-04-01_110637
6,7T	sync_2022-04-02_121818
6,7T	sync_2022-04-03_084334

So the backup is broken...

[traxanos]

so i have delete al snapshots and have start clean. first days all works fine. some days later the cron has generate output with:

ERROR: Could not statfs: No such file or directory

Then snapshots were copied wildly again. The files in the same snapshot on both server has different sizes and are broken. so your scripts has any bug.

[mritzmann]

Is there any effective data missing, or do you just assume that something is wrong because you compare the size? Because of copy-on-write and the general way Btrfs works, you can usually never compare snapshots by size.