What we are actually going to do is pretty much like our LAN Free Backup
when we separated out the media server component, the backup server tells
the client you are going to be backing up and this is the resource. The backup
client will now issue the metadata request but instead of going to the media
server it just sends it down to our data mover.
Our data mover supports the SCSI extended copy command but its now going
to be a block based backup. So typically we will use this for a full volume
So what we’re going to say is you’re going to back up. It starts with our point
in time copy. We still and always need a consistent and usable copy of data.
So we take our snapshot or our split mirror, it reads the data, the blocks will
pass through our data mover and go down to tape. It’s a full volume, block
based backup. But because we’re going through this storage router nothing is
building a tape index. Nothing is building a file catalogue. So our restore
strategy is also a full volume restore. So, it’s very fast to back up and it’s very
fast to do a full volume restore but the problem is if you wanted to restore an
individual file as we don’t know where they are. So you have to restore the
volume. If you restore the volume over the existing volume you will lose all of
So you know there is one file that you need to recover. You will have to do a
full volume restore to spare capacity and then you can copy the individual file
back so now your recovery time has gone up.
There are some vendors who have got very clever. They create their own
snapshots in software and they will issue individual block commands so what
they are actually doing is using this data mover functionality but still building a
tape index themselves.
Serverless backup does not remove all of the servers. We still need a backup
scheduler, we still need a backup client to be running. All it actually does is
removes the media server component and means we can do a full volume
backup and a full volume restore that much quicker with no processor
overhead. The backup software does have to support the extended copy
command. Most of them do. A tape drive or a storage router has to support
the extended copy command