Synology will back up to another CIFS share, RSYNC, or another Synology.
Using two virtual Synology devices I tested using one as a source and a 2nd as the destination.
Backing up a LUN (what Synology calls a "LUN Backup Set") , yielded a bunch of 4gb volumes. I have yet to figure out if it is doing block level backups or not. For instance, let's say one has a virtual machine living on an iSCSI LUN, if only a small amount of data is changed, how much is going to be backed up? The entire VM? The Entire volume?
If they Synology has a CIFS share, and that is told to backup (what Synology calls a "Network Backup Set"), it makes an exact copy on the receive box. So that means no compression or no historical backups.
Two things really disappoint me. The first being the logs and notifications. All the information one gets is if the job completed or not. No mention of the amount of changed data, time consumed, nothing!
Restoring: I haven't tried restoring the iSCSI volume yet. However the CIFS share, it does a full restore of the entire volume! One cannot pick and choose files or folders to restore. The work around there, is to browse to the destination Synology and manually copy off the missing/corrupt data. During my test I simply deleted a chunk of folders from source NAS, did a restore. Surprisingly, it does only copy back the missing data, not the entire data set, as can be seen at on the progress meter.
