One system, two problems: Capacity and performance
We have run out of both time and capacity on our current backup. We back up eight different servers on our network every night. We are currently using an Ultrium drive (100 GB) in one server and pulling all the data across the LAN. Our current total nightly backup is approaching 200 GB. About 10 GB is currently pulled across a 5 MB wireless WAN connection.
So we have two problems: the backup takes about 13 hours (so the backup finishes during business hours), and it will soon no longer fit on one tape. We consider backup very important, but don't want to needlessly spend a lot of money. Would disk backup be recommended, or should we move to a distributed system (utilizing our current technology)?
As you mention in your question, there are two distinct issues developing in your backup environment: one is capacity and the other is performance-related. Let's start with backup performance. With a native (uncompressed) throughput of over 52 GB per hour (15 MBps), the Ultrium I tape technology should not be at fault. A single LTO 1 drive should handle 200 GB of backup data in a little under four hours. This points to the next possible culprit, which is network bandwidth. Backing up 200 GB in 13 hours works out to approximately 4.4 MBps, which is somewhat consistent with an average 100 Mbps network (actually a little slow but close). Of course, this also depends on the type of data backed up and the backup software configuration itself. In any case, you would likely need more network bandwidth to significantly shorten your backup window.
Now in terms of storage capacity, there are a few options to consider. Disk backup is definitely a way to address single tape media capacity issues, but you will have to give some thought to your off-site storage requirements (vaulting). Another option is to upgrade you current tape technology to Ultrium II, which offers 200 GB of native capacity (400 GB at 2:1 compression). Second generation Ultrium drives are also backward-compatible with Ultrium 1 media so you can access longer retention backups or archives. A small, automated tape library would also be a way to address media capacity while reducing the need for manual intervention and media handling.
This was first published in November 2004