This is not new. 8 years ago it didn’t get much take up but all of a sudden
people are finding a use for it because now we create virtual tape libraries.
So overnight we can do disk to disk or disk to VTL. When we do disk to VTL,
if we go through a media server now the media server has built the tape
catalogue and the tape index. So we have a tape catalogue and a tape index
already structured to our virtual tape which means during our production days
its much faster to do a file restore to get individual files back from the virtual
tape libraries because we don’t have to fast forward and find the files we just
remove the heads and read the file.
So a lot of people are now using disk to Virtual Tape Library through the media
server. Overnight the media server can be one of our cluster members.
During the day we want the cluster member back so all of our performance is
there but now we’ve got a virtual tape format sitting here. We’ve got our
production data sitting here and now our data mover can read all of the blocks
from our virtual tape library and very quickly copy it out to real tape. Either
locally or remote.
So now you have your production data, your VTL data and now you can move
it very cheaply to physical tape which could be used for off site protection. It
could be used for more of a disaster recovery. So you’ve got your virtual tape
for operational recovery and your physical tape for disaster recovery. And, of
course we don’t have to worry about building the tape index because if we
move it from the VTL to a real tape, the tape index is already created. All we
have to do is go back and tell the master backup server the tape is no longer
here, the tape is now in this new location (somewhere in our library or
somewhere on another site).
Interoperability is still limited but realistically the simple fact is that whatever
application you use to back up your data you normally have to use the same
one to restore your data.
The extended copy command must be supported by your Operating System.
party copy leverages the extended copy command. But we need to
understand the restore capabilities.