Wanted to ask this "in plenum" in case others have the same question:
What are the implications of changing the backup level "on the fly" in Veeam Backup 4?
My scenario is as follows: All backup jobs recreated after upgrading to Veeam 4, and this time I used the Best compression level for all VMs. All the jobs have been successful and have run a couple of times (full + few differential). Now, I see the CPU load is quite heavy on the servers and want to change the compression level to Optimal instead. I understand it's only subsequent runs of these jobs that are affected (the next differentials), and not the full backup. However, the .vbk would then consist of 90% "Best-compressed-blocks" and 10% "Optimal-compressed-blocks". Over time, this ratio would probably change so that the number of "Optimal-compressed-blocks" increases as more and more blocks change and need to be replaced in the main .vbk file.
My questions is: Is this safe? Is it safe to run in a configuration where the first (full) backup is run as Best compression, and subsequent differentials as "Optimal"? Does it pose a problem when trying to import a .vbk, in case of a .vbk being restored from tape after a few moths?
Like.. how does Veeam know that a certain block is compressed with Best or Optimal compression? Or does it even need to know?
Thanks, Anton
