After almost two years now, what is your opinion regarding serverless backup? Considering all of technology available now, would you recommend using this method?
First, let's define a few terms: LAN-free backup: Multiple backup servers sharing tape drives. Their backups go across the SAN, not the LAN. Client-free backup: I split off an additional mirror (or make a snapshot) that becomes visible to a server other than the server that originally used the data (usually the backup server). Then I back up that server via that other server. The data travels from disk, through the backup server, to tape and does not travel through the client. Thus, the term client-free.
Server-free backup: Same split mirror/snapshot as above but the data is sent DIRECTLY from tape to disk and doesn't go through another server of any kind. Examples include the SCSI extended copy (XCOPY) command that can send data through the SAN from disk to tape, without going through a server or NDMP that can send data directly from the NAS filer to its tape drives without going through another server. True serverless backup is a great technology for those companies that have a need. It can do things that are simply not possible any other way. It does add a significant level of complexity and cost though, so you need to exhaust your other choices before going down that road. Make sure you've tried LAN-free and client-free first.