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Who is Tracy Reed?

I am a Linux enthusiast, a multi-engine instrument-rated pilot, and a traveller. I am interested in all aspects of computing and technology in general, especially Linux and Free Software. As an avid pilot I can be found somewhere over the skies of the southwestern US most weekends.  As a traveller I have been to many interesting places. Check out my photo gallery. Want to get me something cool? Check out my wish list!



If it wasn't backed up, it wasn't important!

by Tracy R Reed — last modified Jan 02, 2009 12:48 AM

I think a lot of people misunderstand ReiserFS and filesystems in general.

I think a lot of people misunderstand ReiserFS and filesystems in general. ReiserFS (3 and 4) acknowledges the fact that cpu is very fast and disk IO is slow. If you can do anything at all in cpu as far as calculations or optimizations to avoid having to make disk accesses it is a win. This is why ReiserFS takes more cpu. Overall it should be faster. It also assumes that your hardware is reliable. If your hardware is bogus you are going to have problems with any fs but particularly ReiserFS. The on disk and in-memory data structures are much more complicated than ext2/3/4. All designed to provide better performance. If you have a memory problem or disk controller problem or really any hardware problem at all you are in deep shit. Want good performance and data integrity? Use quality hardware and implement redundancy!

Journalled filesystems like ReiserFS easily handle power-out problems, accidental reboots, etc. These are not data corruption issues. But once some bogus piece of hardware starts causing random bits to be scribbled to the disk all bets are off. I don't even see the lack of an fsck program as a problem. If you ever get to the point where you need to do an fsck you really should just restore from backup. When I hear these stories about how people lost all of their data because their filesystem "crashed" I have two reactions: 1. Skepticism that they didn't have bogus hardware or didn't somehow screw themselves up. It is extremely rare that anyone can actually prove it was a bug in the fs that burned them. 2. Total lack of sympathy because they didn't have a backup.

Here's what I do:

I value my data so I spent an extra $100 to get another 250G disk and I mirror. $100 is DIRT CHEAP insurance against hard drive related failures. Disks are so cheap and big there is no excuse for not mirroring important data. Plus you get a bonus on read performance. If I offered you $100 to let me delete 250G of data from your machine right now would you let me? Then your data is worth more than $100 also and worthy of a mirrored disk. But a mirrored disk is not a backup. You need backups too.

I have Bacula setup to run every night. It makes a backup of my data to an external USB2 attached 80G drive. I don't back up all of my data as there is some stuff I really don't care about. But all of my email, source code, and vacation photos etc get backed up every night. I probably have 30G of data I really give a care about. I have two of these drives. I do a full backup once a month and incrementals every night after. At the end of the month I take the drive over to my storage unit (or a friends house would do, or even my desk at work) and swap it with a second drive which I have stashed there.

I think I paid around $80 for each of the external drives plus $100 for the extra disk for the mirror. So I have a really great, fast, reliable backup solution for $260 plus some time to set it up. Is it worth it? HELL YES! While writing this I just thought to do a test restore of some data. It worked. Yeay! My backup is solid and there if I need it.

If any one of you offered me...say, $1000 to come over to my house in San Diego right now to boot your own super-destructo CD which did a military grade erase of my HD's I would let you. RIGHT NOW. I have the data backed up. I figure my time to do the restore is worth $1k to me. And I'll have everything back up in 24 hours or less. If you can't do the same right now your data better not be important to you because that's how disasters happen: Completely unannounced.

Remember kids: If it wasn't backed up it wasn't important!

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