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Backed up the wrong database before making a major change.
I tried upgrading from Invisionboard 1.3 to 2.1 using the instructions for going from 1.1, after carefully saving the database. The result was an unimaginable mess. I thought I'd go back to my backup, and — you guessed it — I had backed up the one with the probable-sounding name, but not the one with the right name. I had forgotten that the forum database was created with another site in mind and adapted later...oops!
How I saved myself: In addition to subscribing to the hosting service’s backup feature, at about $20 per month, I also have MySQL database backups set up via CPanel. I was able to take that and save the day...almost. See the next item for what I really did!
Lesson: back up religiously.
Backing up a drive onto itself
I backed up a hard drive once to a second partition on the same drive, thinking I was backing up onto an external drive. Guess what the first and only hard drive I ever damaged (in hardware!) was?
How I saved myself: There's a $2,500 DriveSavers fee involved in that blunder. D'oh!
Lesson: be really careful with your backups and try to make more than one! Especially with databases!
Deleting all the databases at once!
There should be a "dumb-idea" daemon operating in Linux to prevent root users from doing this:
rm -rf /var/lib/mysql
What I meant to do was rm -rf /var/lib/mysql/acp which would have removed the acp directory and allowed me to easily copy in a backup of that database. Instead I deleted ALL my databases, and it took me a while to figure it out!
How I saved myself: Again, we go to the daily backup. I lost about a half of a day’s entries across all systems that use MySQL, and decided I should really be backing up the databases twice a day to separate directories! It’s hard to have too many backups.
Lesson: back up religiously...and often...
Inaccessible backups.
This actually isn’t something I did, but it was a common problem in the day of tape: you'd back up onto something and it would turn out that no other machine could read the tape! (Or cartridge, etc.) The solution was to make sure you could restore with another machine...and check it again every month.
Another problem that most people do is to have their backups in the same place as their machine - Hurricane Katrina demonstrates the problems with that, though few people would store off-site enough to avoid it. (See the next solution for a way out). If your house or office burns down, though, the backup goes with the drive, and where are you then? (Fireproof safes are not usually designed to protect media, so DVDs may melt and hard drives may lose data). Likewise, both can be stolen. Keep a backup off-site at all times!
Erasing your good backup with a bad one.
Another issue, of course, is when you screw something up and then back up the hard drive ... with the screwed up file erasing the old backup. This one happens all the time to all sorts of people. It happened to me most recently with a Mac Plus that I had accelerated; the accelerator board, unknown to me, couldn't handle the blind writes on my hard drive, so the more I used it, the more data got corrupted! Much of it was recoverable; some was not. Yes, I got a refund, and to this day I am leary of accelerators, though I've used a couple of others (sometimes called upgrade cards) that have worked well.
I often read reviews of backup software and techniques that recommend buying a single hard drive and cloning to it. Yes, that creates a bootable drive, a great convenience; but if you delete a file and try to find it on the clone drive....it's gone.
Lessons:
Some packages, such as Synk, archive changed files, which is a major improvement. In the long run, though, I find it helps to solve this and the prior problem by using two systems: Retrospect (or another backup program) backup up my entire machine onto DVDs, with daily incremental backups, and a now-and-then hard-drive clone so I can get right back to work if something bad happens. (I store both a hard drive and a full set of DVDs off-site.) I also use a service that lets me archive a couple of gigabytes easily and cheaply over the Internet using rsync (included on all Macs and Linux boxes, and available on Windows) or SFTP; this takes almost no time to do, and lets me keep a current version of my e-mail and all files across the country, so if a hurricane comes, and I can remember my password and the company's information, I can get back large swaths of my life.
My backups no longer have the file!
If you have a file that's been bad for a long time, it may have revolved out of all of your backups, unless you are smart enough to keep an annual DVD backup. I am not...
Lesson: the Internet Archive (archive.org) can help! It takes about a minute to find old copies of most Web pages!
By the way - magazines talk about DVD-R and CD-R for backup. Discs are nonrecycleable and an environmental disaster. Use DVD-RW and CD-RW; they can be used many, many times. You'll save money in the long run, and do a good thing for your kids and, quite possibly, yourself.
For frequently used files, you can, for a mere $8 per month, get a full four gigabytes - yes, you read that correctly - of backup space at strongspace.com. A simple rsync script (or you can use Transmit or other SFTP software) can upload changed files in seconds or minutes; you can have automated daily backups of your e-mail and client files. Initial transfer takes a long time, as you might imagine, since the Internet is far slower than, say, DVD-RW; but once you get the big files up there, daily backups are a breeze. (Depending on your backup software, this will most likely be a mirror-type backup, so you still should do a regular incremental/archiving backup. But it's a darned good way to avoid losing your current work - even if you lose your entire computer or even your entire state! - assuming you live in a different state than strongspace.)
This page so far as largely been about backup, and for darned good reasons. Take it seriously and use multiple methods in multiple places. Spend money on good backup software if you have to — you want to avoid paying $2,500 to DriveSavers! A single file that may even pay off the entire strategy.