Missing wal files in passive backups

[msartor92]

Hi all,

i'm running barman 3.3 in main site and barman 3.5 into relay site. In relay site I've a lower retention with only last two backup. After some infrastructure issue in relay site I need to retrieve older backup from main site. I've increase retention_policy from REDUNDANCY 2 to 4 and run barman sync-backup <oldest_backup_i_need>. Backup was syncronized but not wals as described into doc. I've run barman sync-wals to try force wals syncronization but this didn't happend. There is a way to syncronized older wals?

Thanks

[mikewallace1979]

Hi @msartor92 - when Barman is running as a passive server it uses a file named sync-wals.info in the wals_directory for that server to track the most recently copied WAL segment. It should be possible to force Barman to sync older WALs by deleting that file (or moving it to a safe location) and re-running barman sync-wals.

For example, with a passive Barman server named main I have an empty directory for an older WAL prefix:

barman@passive:~$ ls -l main/wals/0000000100000001/
total 0

The sync-wals.info file indicates a more recent WAL segment, so barman does not sync these older WALs:

barman@passive:~$ cat main/wals/sync-wals.info 
000000010000001000000017.00000028.backup        8103
barman@passive:~$ barman sync-wals main
barman@passive:~$ ls -l main/wals/0000000100000001/
total 0

If the sync-wals.info file is unavailable, Barman will sync all the WALs it knows about, so the older WAL segments are copied across:

barman@passive:~$ mv main/wals/sync-wals.info ~/
barman@passive:~$ barman sync-wals main
barman@passive:~$ ls -l main/wals/0000000100000001/
total 16388
-rw------- 1 barman barman 16777216 Jul  6 15:34 000000010000000100000096
-rw------- 1 barman barman      343 Jul  6 15:34 000000010000000100000096.00000028.backup

[msartor92]

Hi, that's pretty usefull, i thought that it would be possibile via cli, for example to force wal sync from a spcecific backup

[mikewallace1979]

I agree - a cli option to force a complete resync would be useful here.