Command to make instant snapshot only, to transfer it later

[MurzNN]

Projects often use several storage types together (eg mysql db + files + solr db + redis db), so for make a backup with consistent data we need to make a snapshots of each storage volume as instantly as can.

But when we executing serial backups via calling btrfs-sxbackup in script, each next backup will be delayed by transfer job, so the time difference between snapshots will be significant.

Solution for this problem is using separate command like btrfs-sxbackup make-snapshot /location1 /location2 /location3 that will only make a snapshots, and transfer them to destination later, via separate commands. What do you think about this idea?

Alternate possible solution is to use one large btrfs volume for all storage types and keep whole data on one drive, but this is not good for flexibility (can't mount with different options) and data reliability. So the solution to instantly snapshot multiple separate btrfs volumes must be much better.

[masc3d]

you could try to setup local job for each subvolume / db and remote backup job for each local backup volume.
however, I never tried or tested this configuration.

[MurzNN]

And other way - implement passing several source targets to btrfs-sxbackup, so it will make an instant snapshot for all of them as first step, and after this - sequential transfer jobs.

[masc3d]

I dont think its a good idea.
btrfs-sxbackup should remain as simple as possible and rather act as a building block for more complex scenarios.

[masc3d]

reason why it's non-trivial, for remote incremental transfer to work reliably, you have to keep track of the latest snapshot. current implementation will create a .temp.. snapshot which will only be finalized once the transmission is complete and cleaned up when the transmission is interrupted.

for your proposal to work reliably, you'd have to track latest snapshot in another way and make fundamental changes to how jobs are implemented.