In the office, we currently have about 120gb of disk that need regular backups. We wanted to have a solution that enables us to store offsite copies easily and wasn’t too expensive. Tapes were out for handling reasons — those drives that we were willing to afford would have meant a system of cascaded incremental backups, making restoration of single files a tape-shuffling issue. DVDs don’t hold enough data and their storage times are not yet fully understood, so that didn’t quite sound so practical, either.
In the end, we decided to outfit one of the older machines around (a Pentium II) with removable hard disks (normal Western Digital 160 GB drives, fitted into run-of-the-mill aluminium mobile racks). We have two drives fitted into a carriage, so there’s always one at home and one in the machine. During the day, the appropriate machines copy their data onto that one volume over the network and I can take along the disk in the evening, bringing the other one next morning.
Most of our machines run NetBSD so I’ll just quickly run down the very basic configuration, we have here, but it should also work with many other unix-like operating systems. Operating system and all esential stuff is on a disk that always remains in the backup machine, the backup volume is a drive off the secondary IDE controller.
The machine is only powered on when the disk is in, so there’s no choking on missing disks — this could be avoided by using a hotswap-enabled IDE controller, but currently, we don’t have that need. As soon as the disk goes in in the morning, the machine is powered up, boots and shares the backup volume via NFS. The other machines (all running NetBSD) have that volume in their automounter. Scripts are started that use dump(8) to copy their appropriate slices onto the backup drive. As soon as they’re all finished, the machine powers down again, waiting for the drive to be taken out.
And that’s all there is to it!
Price of the machine: practically nothing, we had that already. We even had an empty 4U 19″ enclosure, so it’s gone into the machine rack.
Price of the drive enclosures: 25 € each, making it 50 €
Price of the hard disks we’re using today: starting from 80 €
That makes our configuration total 210 €. Not bad for 160 GB of backup storage.
