You can use the dpmbackup -replicas as a scheduled option to create a point in time snapshot of the DPM data on your DPM server that could be backed up by a third party solution. The problem with this is that as soon as you do you lose the 'application recovery'
capabilities of DPM.
Because of the way that DPM is architected for disk based backup it uses an up to date copy of the data on the replica volume and a record of the changed data in VSS snapshots on the recovery point volume. This means that if you attempted to restore the
data from tape back into DPM, overwriting the replica or recovery point volumes, you would break the ability to restore. You would also lose any subsequent backups from that point.
The only "DPM legal" way I know to do this, would be to let DPM have access to a tape device or virtual tape device so it can grab the data back and use it's "application recovery" capabilities. In theory you could use something like firestreamer to create
a backup to disk and and have your main backup solution pick up that file and dump to tape. You can then restore that virtual tape file and import back into DPM and restore SharePoint data from there - but that means you'd need to purchase firestreamer.
Hope this is helpful.
