Could not find any snapshots to destroy; check snapshot names

OpenZFS Sanoid
1

Hello,

I have the following setup for backup.
A>B (every night)
B>A (every night)
A>C (once a week)

Servers A and B have sanoid running but server C does not. Server A and B are up all the time while server C is for cold backup i.e. it gets turned on once a week, takes a backup and switches off.

I am seeing the following warnings when doing A>C transfer,

Sending incremental tank/owncloudfiles@autosnap_2024-08-26_00:00:58_daily ... syncoid_nas_2024-08-27:09:28:47-GMT05:30 (~ 2.8 MB):
2.66MiB 0:00:00 [7.65MiB/s] [======================================================================================================================================================>            ]  93%            
could not find any snapshots to destroy; check snapshot names.
could not find any snapshots to destroy; check snapshot names.
WARNING: ssh   -S /tmp/syncoid-root@172.16.1.79-1724731126-8937 root@172.16.1.79 ' zfs destroy '"'"'tank/owncloudfiles'"'"'@syncoid_nas_2024-08-26:09:56:08-GMT05:30;  zfs destroy '"'"'tank/owncloudfiles'"'"'@syncoid_nas_2024-08-26:14:10:09-GMT05:30' failed: 256 at /usr/bin/syncoid line 1596.

Is there anything i need to do about this or are these harmless warnings?

2

You should not be creating snapshots on anything except for A. (Assuming that A is the production system.)

You’ll want to RUN Sanoid on all 3 so it can prune old snapshots, but make sure you configure your sanoid.conf to not take any snapshots on the backup hosts. If you lose your common snapshot point, you’ll have to do a full replication again.

This particular message looks to me like syncoid is trying to find one of it’s sync snaps to destroy, but it doesn’t exist anymore.

3

Both A and B have production data while C is solely for backup.

Sanoid on A is defined such that its own dataset use the ‘production’ template while dataset of B use the ‘backup’ template.

Sanoid on B is defined such that its own dataset use the ‘production’ template while dataset of A use the ‘backup’ template.

Server C is mostly switch off, so i am not sure whether running sanoid on it will make difference.

Should i be doing this:
A>B (daily)
B>A (daily)
A>C (once a week), only A datasets
B>C (once a week), only B datasets