I wonder how many people have recovered an entire server from tape. I tried once and it failed rather badly.
First, the boot CD made by Veritas wouldn't boot on the server, although it would boot on workstations. Second, there was no alternate method provided by Veritas to do a disaster recovery. The OS had to be reinstalled and reconfigured manually before the tape could be cataloged.
I do all backups to external hard drives now. I have tested disaster recovery with them and it works. I use ASR backups.
I've done it several times. Worst case was on a VAX 8810 running Ultrix. I had to boot off 8" floppies, then load the box from 9-track tape at 6250 bpi. That's just a little over six thousand bits per inch for those not familiar with such low values :-)