Deep Backup

I noticed a recent thread about backup over at comp.os.linux.misc where someone asserted that the value of backups fades very quickly with time, and that there is no value in long term backups.

I disagree rather strongly. Many a time I have resurrected data from "old" tapes when it was found that the new tapes were unreadable or that important data had been damaged some time ago without being noticed - the "useless" old tapes had the data. I encourage having at least an "end of last month" set and an "end of last year" isn't a bad idea either.

Sometimes the availability of this old data has been of forensic interest - I've had customers who have been the victim of embezzlement or other computer crime and the availability of old data allowed reconstruction of the crime. I've also had customers experience disasters where they have lost everything, and found that their current backups were also damaged: the ancient data wasn't a great place to start rebuilding, but it was a heck of a lot better than nothing at all.

It's just not true that the value of backups is ephemeral. For example, some of the Cobol programs I took from a very old sco box and brought to life on a Linux box should have been on tapes; it was fortunate that the drives hadn't died completely:Transfer SCO Acucobol to Linux. As the programs themselves hadn't changed in years, even a very old tape would have been valuable.

By the way, later in the thread the person who said long term backups had no value stated that "archives" was the proper term for what I was referring to as long term backup, and that archives are valuable. I fail to see any important reason for this distinction: an "archive" is still an old backup. Some folks call current backups "archives" too, so to me it all sounds pretty much the same. It's a tape or other storage medium; all I want to know is what's on it and when was it made. Call it whatever you want.

However, speaking of overkill: Every Single One was an example of saving just a little too much.

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3 comments

Tue Sep 6 05:50:12 2005: 1057   PaulJacksonpjusanet


I've probably thrown out a dozen generations of tape drive, that were
no longer practical to keep running on newer hardware. So ancient historical
backups on tape are impractical, except in the rare case they have something
so valuable it is worth reconstituting the hardware needed to read them.




Fortunately, disk drives have been getting bigger faster than my expanding
data can keep up. So I keep my ancient backups online, right on my desktop
disk. I can go back 10 or 15 years and find files. For the last few years,
since I've started doing disk to disk backups for my initial backup, I can go
back to any -day- and recreate what I had and did not have, right online.




I then backup the on-disk backup to removable storage, so that I can rotate
offsite storage and handle disaster recovery. For my desktop, that removable
storage is just more IDE drives, as their cost-per-bit is now much lower than
tape, and they continue to increase in size at (surprise, surprise) the same
delightful rate that my main disk drives increase.



Tue Sep 6 14:00:53 2005: 1058   BigDumbDinosaur


However, speaking of overkill: (link) was an example of saving just a little too much.

It's also an excellent example of what happens when you make assumptions about what someone does or does not understand. <Smile>

I've probably thrown out a dozen generations of tape drive, that were no longer practical to keep running on newer hardware. So ancient historical backups on tape are impractical, except in the rare case they have something so valuable it is worth reconstituting the hardware needed to read them.

I don't think old tapes are impractical. How hard can it be to reinstall the older drive if needed?

So I keep my ancient backups online, right on my desktop disk.

If the files are "online" they aren't backups and will be lost when the disk fails (and *all* hard drives eventually fail -- it's just a question of when). In fact, routine handling of a portable hard drive can cause it to fail. Copying data to another hard drive isn't backing it up, as the medium being used is inherently unreliable over the long haul.



Tue Sep 6 14:06:01 2005: 1059   TonyLawrence


I read his comment to say that he backs up the archives on the disks to removable media also..

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