In the Air

By Jerry Pournelle

October 27, 2003

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Column 279 (Continued from the Previous Week)

RAID and Backups

After mentioning RAID in last month's column, a reader emailed to say he was perfectly happy with his mirrored drives using Intel's motherboard RAID. My reply was that on-board RAID was a fine start, but it wasn't going to protect you against a power-supply failure frying both drives; accidental deletion; or system theft. Chaos Manor has been hit with both of the first two, and my son Richard had his laptop stolen out of his truck out back. So, I wouldn't consider two drives in a single case to be an adequate backup.

Of course, I'm more paranoid than most, and so I end up saving everything I write to four or five places, press copies on passersby, and send another to Elbonia for something like safekeeping. You probably don't have enough PCs to save everything five times, but you certainly have options.

What media to use? Tape is rapidly becoming an option only for the high-end; CD (or, if you have one, DVD) burners are the obvious first choice. There are over-the-Internet backup options, but they're not inexpensive. Windows XP does have a relatively simple way to cause backups to be written to a CD, though you probably want a third-party application like BackupMyPC or Nero Burning Rom to manage this more simply. In any case, don't trust all your data to a single computer, even if it has a RAID array.

An afterword on tape: It's messy, it's inconvenient, tape can be expensive, but overall it's pretty cheap compared to losing your data: and tape is orders of magnitude more reliable than most optical media. This isn't so important if your data are mostly text where bit-for-bit accuracy isn't so critical; but with numerical data that's another story. It is precisely the need for data reliability that brought about the invention of DVD-RAM, still by far the most reliable of the rewritable DVD options (and also increasingly hard to find).

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