Backup data volume - comprehension question...

[TommyB]

Hi,

when looking at the backup jobs for my Exchange server, I typically see the following numbers:

Processed: 225GB
Read: 16,1GB
Transferred: 6,6 GB

The numbers for read/transferred vary from job to job, but only a few GB more or less.

When I look at the actual size of the backup files on disk, there is a .vbk file with almost 156GB and several incrementals ranging from 5 to 10 GB

I'm actually wondering how this can be, especially for the full backup file, shouldn't there be a backup job with much higher "Transferred" amount?

Is this what "synthetic full" does? Is the .vbk file not actually backed up in realtime but the result of merging older incrementals into a new full backup?

Thomas

[foggy]

Is this what "synthetic full" does? Is the .vbk file not actually backed up in realtime but the result of merging older incrementals into a new full backup?

Exactly. If you're running synthetic fulls (not active ones), VM data is not retrieved from the datastore to make the next full, but the full backup is rather synthetically built up from the data you already have in the backup repository. So the amount of transferred data is the size of the incremental changes, as an ordinary incremental job run is always performed prior to creating synthetic full. Please refer to the corresponding user guide section for more details. Thanks.