Hello Tim,

imho VTL's are more flexible then Disk Backups.

You can share disk space of the VTL with several NetWorker Servers and
Storagenodes. In one data zone you can have several (dedicated) storage
nodes sharing the VTL with the backup server. No drive sharing licences are
needed because of every server can have its own virtual tape drives. You
only need to license the slots and the (dedicated) storage nodes. Another
advantage is that if one virtual volume is full NetWorker uses the next.
With Disk Backup he waits for free space on that volume (only new savesets
go to other volumes). You can also share the disk space of the vtl with
different operation systems (e.g. Backup Server RHEL, Storagenodes Windows
and HPUX). Directed restores can use the own virtual tape drives with
volumes written from another storagenode.

Disk Backups have the advantage of concurrent backups and restores, but You
can handle this with smart configuration of VTL Slots and the size of the
virtual volumes (e.g. 128 Slots with 100GB per volume instead of 64 Slots
with 200GB per volume).

Birk


On Tue, 30 Oct 2007 08:31:17 +0100, Tim Verbois
<Tim.Verbois AT ET.VLAANDEREN DOT BE> wrote:
> Hello,
> 
> we bought a VTL recently, but now I'm asking myself: why a VTL, why not
> just Disks?  Networker is perfectly capable of using Disk backups
> instead of the VTL.  Disk backups have some advantages over VTL what I
> know:
> 
> - when cloning, it is not needed to skip the not used sessions when
> parallelism is high
> - possibility of purging recycled save sets on a disk device (1 good
> saveset on a tape makes it impossible to recycle the tape)
> 
> Why would you choose a VTL then?  Any thoughts?
> 
> Tim
> 
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