Easier Choices

Max out your memory. Having lots of free memory will improve your virtual-memory performance. Fortunately, with RAM as cheap as it is now, a gigabyte or three is unlikely to bust your budget even if you're economizing.

You'll need CD-ROM or DVD-ROM drive (you'll almost certainly be installing your Linux from it!). You have a SCSI system, so get a SCSI CD-ROM. That's pretty much the end of spec, as there are only a few models of SCSI DVD-ROM and SCSI CD-ROMs are a very generic item. The only significant price driver is their speed -- 8x, 10x, or up (it's hard to find lower speeds anymore).

We'll want a good high-volume backup device, too. This isn't quite the pressing issue it once was; nowadays, large disks are so cheap that backing up your home directory to another disk seems an attractive alternative. But it's still good to be able to make backups that you can separate from your system and store off-site in case of disaster.

The huge increase in disk capacity in the last five years has pushed a lot of once-popular backup technologies to the wall -- QIC tapes, ZIP drives, and magneto-optical storage just couldn't cut the mustard. The only realistic choices these days are DDS drives (high-capacity tape drives using an encoding method similar to DAT audio) or writeable CD-ROMS.

We'll go with DDS because it's of much higher capacity. But even if you're building on the cheap, the apparently less expensive CD-ROM burners aren't really a good idea for mass backup. The problem is the per-megabyte cost of the media, which you can't reuse. Rick adds: "Tape is also faster, more rugged both in storage and in the process of recording (jostling a DAT drive doesn't destroy the ongoing backup), doesn't require gobs of scratch space for assembling image files, and is way, way, easier to automate."

And, speaking of faster, one of the things you want most in a tape drive is transfer speed. Every Unix system administrator knows how maddening it is to listen to a tape drive making that dicing-celery sound as a backup stretches on...and on...and on...during time you really ought to have been home in bed. We'll keep a close eye on this figure of merit. This is a good reason to go with the newer DDS4 tape drives, which have speed typically half again that of the older DDS3 drives.

What goes for CD-ROMs as backup media is also a serious strike against technologies like Ecrix's VXA or Hewlett-Packard DLT tape, even though tapes are reusable. They give you better capacity and speed, but down the road you get killed on the media costs. They're not really a good choice for a personal system.