I'm not sure exactly what to search for here, but I tried "Disk to Disk to Disk" and "Private Cloud" without much luck. I want to back up to disk and then back up the storage pool to a private off site location (but for all practical purposes, I could be backing up the storage pool to another storage pool on-site as far as the servers know, depending on how I configure the networking). Since the location is actually off-site, I don't want to do full backups of the storage pool, I want to do differencing backups so that the amount of data transferred off-site is minimal. Old revisions of the off-site storage only need to last weeks or months, not years, so tapes (virtual or otherwise) would ideally not be involved.
The only things my searches turned up seemed to advise using virtual tapes and the like, but I'm concerned about that meeting my needs. Specifically, if I'm using virtual tapes, I would expect a full backup to be required any time I wanted to purge incremental backups. In other words, with virtual tapes, I believe (perhaps mistakenly?) that my options are to have my storage needs grow infinitely or my data transfer needs skyrocket occasionally, and neither of those are good options.
Is backing up one storage pool to another supported? If not, is there something I'm missing with in regards to how a virtual tape option would work? If not, is there some other way to achieve this goal (for instance, effectively be creating my own local Azure storage destination or something)?
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