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02/28/2004 Archived Entry: "Backups"

Who says techies aren't poetic? Dozens contibuted Nigerian "419" scam haiku to the Register's contest. My favorite is

Autumn's email flood,
Small advance ensures windfall.
Outside, swine fly south.

Then there is this remarkable poem about the SCO/IBM/Linux flap, both stylistically and factually accurate, in the style of Edgar Allan Poe's "The Bells".

In last few days we've started receiving copies of the latest virus email (apparently MyDoom-F). These appear with cryptic subject lines and very short message bodies, so my spam filter isn't catching them. Fortunately my common-sense filter tells me not to open a mysterious email attachment with a .zip extension (and my email program shows the extension). Alas, judging from the number of these we've received, common sense is still rare...and some people are going to learn a hard lesson when this virus starts deleting their files.

Which brings me to the topic of backups.

I know people who have used their PCs for years, sometimes for business purposes, and yet who have never backed up the contents of their hard drives. Evidently this is not unusual; a recent survey of UK comapnies found only 20 percent back up their desktop PCs. (I presume that server computers get better treatment.) So if you haven't done so already, now would be a good time to establish a backup plan.

Backup needs vary widely. A business that is reliant upon its computers may need to do daily backups to magnetic tape, and store them off-site (in case of fire or other disaster). A "personal" PC used only for web browsing, email, and occasional word processing may get by with a once-a-month backup of personal files to a floppy disk.

We're in the middle. I do a weekly backup of our "work" files -- these are the files we've created, like manuscripts and computer source code. Right now I'm doing a complete copy of these files to CD-R, which takes two or three 650 MB recordable CDs (costing about a dollar a week).

As it stands now, a disk crash at the wrong time could cost Wendy or me a week's worth of work. I'm working on a script that I can run each day, which will do an "incremental backup" to a ZIP disk of just the files that have changed that day...but that's still being debugged.

Every three to six months I used to do a complete copy of our hard drives. (Back when we had 3GB and 4GB drives, this could be done on ten CD-Rs.) This saved my bacon when I had a catastrophic Windows crash, since I was able to recover the registry and the DLLs. If you are running Windows, I recommend you back up your registry and system files regularly. (Alas, Windows really isn't designed to make this easy. You can get most of this by backing up the root directory C:\ and the \windows directory and subdirectories.)

Now that we have 20GB and 60GB drives, dumping the entire drive to CD-Rs is a bit excessive. So I've resigned myself to reinstalling the operating system and applications from scratch, if I have a major meltdown. I keep copies of every program I've installed -- either purchased or downloaded. The downloaded files get copied to CD-R so I don't have to download them again -- and occasionally they become unavailable (especially older versions). If my hard drive went up in smoke right now, I estimate that I could do a complete reinstall in about a day...a reasonable risk/benefit tradeoff for me.

Unfortunately, I haven't yet found any satistfactory backup software for either Windows or Linux. (My requirements are rather demanding, since I'm trying to do network backups of a mixture of Windows and Linux PCs.) In my Windows days I'd use Easy CD Creator, but it wasn't too bright about new directories, couldn't fetch files over the network, and couldn't split the backup into several CDs. For Linux I found a useful shell script that does automated backups; I've been modifying it to write CD-Rs and ZIP disks and to do network backups, but it's still a work in progress. For the less technically inclined Linux users, right now I can only suggest using whatever CD writing software came with the distro (like X-CD-Roast).

Of course, if it's not a hardware failure, but just an operating system implosion -- which I had twice under Windows -- I have an alternate plan. I keep a copy of Knoppix: this is a Linux that boots and runs from CD-ROM, and can read both Windows and Linux hard drives. This would, in a pinch, let me transfer my work files over the Ethernet to another computer.

Meanwhile, here are some suggestions to make backups easier:

• Keep your work files in a separate and distinct location: either a specific directory, drive, or partition on your hard disk. (I used to keep all my work files on drive D: under DOS, then on directory C:\d under Windows, and now in a separate \home partition under Linux.)

• Install a CD-R/CD-RW drive. Floppy disks are just too small for backup these days, and both CD writers and blank CD media are quite affordable. I now make it a policy to install a CD writer in every "working" desktop PC. (Those with really huge backup requirements might want to install a DVD writer.)

• Find program that supports incremental backup. An "incremental" backup copies only the files that have changed since the last backup. This is smaller and faster than copying your entire working directory; you can do it daily. The downside is that if you have to restore your disk drive, you need to restore from to the latest "full" backup, and then from all of the following incremental backups. So you still need to do periodic full backups. We'll do incremental backup daily, and full backup (of work files) weekly; you might be able to do incremental weekly, and full backup monthly.

• Test your backups. Make sure you can read the files that you've saved to a backup disk. At the very least, use a program which can verify the CD (or other medium) after writing. An ambitious but worthwhile exercise is to try to restore, to a second PC, all the files that you backed up from your first PC. (I do not recommend you try doing a full restore on your first PC as a test; if your backup is corrupted, you can lose everything.)

• Establish a backup schedule. Pick a day of the week (or, for daily backups, a time of day) when you back up your computer, and stick to it religiously. Make it a habit.

I'm currently exploring the use of CD-RWs (rewriteable CDs) for my weekly backups. When these were new, they were quite expensive; also, I'd heard they could only be used a limited number of times, and could only be read in the drive that recorded them. An acquaintance in my local Linux Users Group tells me that all of these concerns are groundless, although it may still be the case that they can only be read in a CD-RW drive (not an ordinary CD-ROM drive). No problem for me (or him) since we have CD-RW drives everywhere.

I'd be curious to hear about others' experiences with CD-RW media, and also any pointers to good Windows or Linux backup software. (Especially Linux software that can do incremental, network backups of mixed operating systems, to multiple CD-R and ZIP volumes.)

brad