We looked at Crashplan and thought I had checked that it does NOT do block level backups, so rather gave it up. (We also found that it was DESPERATELY slow as it only managed 2 -3 Mbps, even though we have 100+Mbps available upload . . . they let everyone share their available bandwidth!) However, I have just found this on their site . . .
"After initial backup of the file is complete, only new or changed information is sent when the file is backed up.
When CrashPlan scans a file, it knows that the file changed and the progress bar runs through the file as if the information is new. But as it goes, it discovers the information hasn't actually changed and only transmits the new information to the backup destination.
For the technically savvy: CrashPlan does incremental deltas by block within the file."
However, having ditched Crashplan I have been testing Google Cloud Nearline (using Cloudberry) which is definitely block level. I have had to do a cunning tweak, to convince Cloudberry that it is backing up the same file, even though Veeam has changed the name/date of the VBK file. I have a little batch file which creates a generic named (Windows) 'hard pointer' to the VBK file, and ask Cloudberry to backup this hard link. It does take quite some time to analyse the file before sending, as it has to compare every block with what it had before (I presume), but does then just backup the incremental blocks. . . . I haven't yet looked at restoring, as my initial tests are still progressing. A 2TB VBK file took 5 days to backup (first full backup) and its first incremental is tomorrow. Looking forward to 'per VM backup chains' as a means of spreading these initial full backups.
Happy to keep you all posted as we progress.
Computer Manager at Bedford School, UK (since 1999).
Veeam user since 2009.