The Merge functionality is definitely present in urBackup, e.g. it’s used for restoring a backup. For this reason, before another backup occurs, the backups are definitely merge. The only thing I am not sure about is, which backups are merged. But that is easy enough to find out… will be doing a test soon.
UPDATE: Just did a test. So what happens is, that it does a full back-up – while calling it an incremental back-up. In other words, it now says that it has one full back-up and two incremental back-ups, but the newest incremental back-up is actually a full back-up.
This seems inefficient. A cheap SSD will wear out much sooner if it does full back-up instead of merging previous incremental with last full back-up and doing a new incremental.
Most of the times, only tiny amount of files are changed between two incremental backups. So better approach is that it merges 1st incremental with the last full back-up and do a new incremental. This will save network bandwidth and disk resources very much
In this case, it’s probably a good idea to transition to a File back-up instead of Image back-up: that one works as you expect it.
Update: I did not take into account the fact that nightly clean-up is what performs maintenance tasks. So it is quite plausible that the nightly clean-up is what merges the image back-ups in a way which preserves one full back-up and two incremental back-ups. Unfortunately, this does not address your SSD wearing-out issue, or the network bandwidth issue – if anything, this increases the amount of disk usage, since now you are storing a full back-up, and then performing more disk operations on it later to convert it into an incremental image back-up. However, the required storage amount should be correct after the nightly clean-up maintenance is complete.
Since it does not address the two concerns that you mentioned, then I plan not to test for, what exactly the nightly clean-up does as far as merging the images goes. In case someone needs it, you can let me know here, and then I can do it.
If it creates new incremental image backup and merges 1st incremental backup with last full backup in nightly clean-up/maintenance instead of creating a new full backup then this is good and efficient.
This will definitely save bandwidth because only changed data is sent to server from client.
And this also saves disk space after merge is done in nightly clean-up/maintenance. SSD wear will be lower because only changed files are getting merged instead of a new full backup writing all data to ssd again.
I will check for and confirm this behaviour by checking if it creates a new full image backup or a new incremental backup after “Maximal number of incremental image backups” count has reached.
