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Owner's Manual
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The time to prepare for an emergency is not AFTER
the emergency. |
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Geeks like the term "Rust" for magnetic
media because the medium itself is Ferric Oxide that gets magnetized into an On
(or high) bit or demagnetized into an Off (or low) bit. On-Off (aka Binary) is the
language of all computers, including the one that is storing your Doctoral Thesis,
Novel, or QuickBooks data. And since that little magnetic charge is so ephemeral,
we want to take steps to make it last longer. |
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Backup your data in several ways: By far and away the best form of redundancy is paper. Paper is good for hundreds of years, is relatively cheap and as a backup system is extremely easy to implement. Just print your stuff out periodically and put it in the file cabinet where you can find it again if needed. The upside to this system is you can implement it immediately without a lot of capital outlay. Unfortunately it also has several downsides. |
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Rule #1: A Backup is only as valuable
as you can Restore from it. |
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Returning the above paper backup to rust is going
to be a horrible chore at best. Data entry is neither fun, nor cheap, so another
form of backup is also called for. |
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Burn CDs? That's a good idea. CDs aren't magnetic,
they're optical media. On-Off is determined by a laser that reads reflections from
the foil of the CD as On (high) bits and no reflection as Off (low) bits. A CD burner
creates the above scenario in a couple of different ways. Burned CDs (write once,
read many) actually burn a hole in the foil to represent Off, and then don't burn
the foil where they want an On. CDRW is another type of technology that is supposedly rewritable. This uses a more expensive type of media and the burner wrinkles the foil to represent an Off bit and then I guess when you rewrite the media it smooths out the previous wrinkle during the rewrite process. I'm not really convinced about the basic concept in the first place, and we've also found that many rewriteables make a record that can only be read by the device that "rewrote" them. So I've been telling our clients to forget the rewrite thang and just stick to real burnt CDs for their backups. This is a fairly permanent record, the guestimate is that a CD archive should last for up to 30 years. Jury is still out on that figure, since CDs aren't even 20 years old yet, but think that's a good guess. Downside to this technology is that CDs are a lot more flimsy than Hard Disk Drives, so you run the risk of them getting broken which invalidates rule #1. A fireproof safe won't protect a CD, the safe is designed to keep its contents below 450 degrees farenheit which is *way* too hot for plastic to survive. The final downside is capacity. CDs are only good for about half a Gigabyte or so of data. Definitely not adequate for modern backup needs. DVD burning might well change these rules, but for the last several years we've been recommending removable hard disk drives. |
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Rule #2: You can only restore from
a Backup that actually gets done. |
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This rule might seem silly, but that doesn't make
it less true. Backups have to be as automagic and painless as inhumanly possible,
or they just don't happen. This is yet another drawback to the CD burn solution.
Someone has to sit down and feed the media to the system and punch the buttons and
that someone invariably has several dozen other things they have to accomplish right
NOW that stops them from getting the backup done. |
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We get around this with software that wakes up
in the middle of each weeknight and freshens the backup media which--in this case--is
a cartridge containing a hard disk drive that can be removed from the computer with
a handle. Said removal is the only thing that the backup person has to remember
on a weekly basis (usually Fridays) and that drive then goes off site as yet another
redundancy factor. We sell this system with three drive cartridges. One in the backup
system right now, last week's backup sitting next to the computer and two weeks
ago's backup off site in case of an explosion or fire. This system, though more
expensive than the CD burn solution is quite affordable, very redundant, very robust
and has proven extremely reliable in the majority of our client's sites for half
a dozen years now. |
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Redundant Array of Independent Disks is software and hardware technology
that "glues" multiple hard disk drives together into a single storage
volume. Your data is stored in several places (redundantly) inside this volume and
software keeps track of it in such a way that when (not if) one of the physical drives
fails, the array is able to continue giving your data back to the system until the
failed drive can be replaced. Whereupon the array then populates the new drive with
data, all the while you're running uninterrupted. Although very cool technology
that we recommend in many applications, it's important that you not make the mistake of thinking you're
covered when you deploy R.A.I.D., it won't protect you from a total melt-down of
your server or a fire in your office. When the entire array is destroyed, you'll still want to turn to your most recent backup to recover from the disaster. See "Rule number Two". |
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Computer Storage Media is not very permanent,
it can allow all your data to go away with relative ease. Redundancy is the best defense against this loss and is defined as multiple copies of critical data in multiple physical locations. A backup is only as valuable as you can restore your data from it. You cannot restore your data from a backup that wasn't done. R.A.I.D. is cool, but it is NOT a backup. Call PMAco now to arrange for your protection. (503) 852-9509 |
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Doug Hood PMA Consulting |
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