I found answers a few qestons:
Image backups:
- What is the difference between incremental backup and full image backup? In case with file backup the server downloads only new files in incremental, then in the case of images this mechanism cannot work.
If the storage file system is btrfs and the raw image file format then full images will be disabled. All image backups always incremental! This is due to the features of the BTRFS file system.
More information about it:
- There is a 3GB file, create an image backup, then copy this file 3 more times. Then create an image backup again. How much disk space will the new backup take?
We copied 3 times a 3 GB file. These files took up additional 9GB of disk space, so they used blocks on the disk for 9GB of space.
The new image backup take 9GB at storage(without compression), because incremental image backup copy changed or new blocks (512 kbyte chunks), so UrBackup will copy this new blocks which size is 9GB.
I checked this and the numbers match (df -h 9Gb more).
If anyone knows answers to another questions, please, answer!