Near-Line backup strategies?

[Pete]

I'm designing a backup system that needs to approach *near-line* more than our current one - and thought I'd throw it out there for anyone that has done anything similar.

 

We're currently running Retrospect 5 Workgroup on Mac OS 9.2.2 to back up approximately 30 client machines. This machine is also running AppleShare IP.

 

The backup currently running is a standard full on Friday nights, and incrementals on all other days of the week. The backup device is an Overland Data DLT loader with 15 tapes per magazine. The approximate amount of data being backed up currently is approximately 650 gigs.

 

The finished set of tapes are physically removed from the location every Friday morning.

 

Some machines on the network are running Gigabit Ethernet on copper (maybe 30%)... while the rest are running 100Base-T.

 

We had a recent situation in which a very important client machine hard drive bit the dust on a Friday morning at about 10AM - right after the tapes had been removed from the premise. The tapes needed to be recalled - which were still on the truck of the off-site data storage company.

 

Long story short - when you need your data immediately you need your data immediately. You can't wait for trucks and the hours it requires for full drive restores from DLT tape.

 

Now I have been tasked with designing a redandant backup system to operate in parallel with the existing one - which hopefully will keep the data much more accessible than the "building-burns-down" system we have implemented right now. I need my data backup approaching near-line.

 

SO... What's the best solution here? I can set up a separate backup server and back-up the clients AGAIN to a simple hard disk... which would aid in speed of restores (that would be one massive drive array). As you can imagine, the backup window to complete a full backup starting on Friday nights is quite long. It can run into Saturday afternoon or occasionally even Sunday - so running them back to back wouldn't work. Potentially, the full backups could run in tandem simulatenously with a slight time shift - basically executing the same script with a few hours or so shift beetween the two, as to not step on one-another.

 

The idea of creating another backup system which would execute this same backup AGAIN seems silly though. Intuitively the data should be backed up once - to hard disk - and then locally from that disk to tape for off-site storage. This of course is one additional step in the backup process - and while unlikely - adds additional potential for problems.

 

On top of this - we don't want to risk losing an entire days work. So the backup needs to occur during the day as well. How are other people managing this? Is there a way to lock-out the user during lunch - for instance - while the mid-afternoon backup runs? Or the 10AM... 1PM... and 4PM backups? If running this often, the amount of changed data would probably not be too large - minimizing this said lock-out. What about files and applications that are open and hot during this time?

 

These ideas are off the top of my head without too much background thought. Are these things Retrospect can do even? Anyone with a completely different angle?

 

The company which this is for is (ahem) a bit demanding, and will not stand for anything less than the best solution with the least possible amount of data loss.

 

Thanks for any and all input.

 

-P