How can I minimise data corruption?

Question

Mac OS X is great, and one of the greatest things it has achieved is an environment so stable that it almost never crashes.
However, for me the next BIG problem with using computers is data corruption. Data corruption problems bug my life as much now as system freezes/crashes did 5 years ago.
For some reason, it often seems to be preferences files that become corrupt. I don't know why, or whether other files are becoming corrupt too and I've not discovered it yet. Sometimes I wonder whether it's just because of all the junk I install, or the length of time it's been since doing a clean format. However, with my recent purchase of a Macbook, and within a couple of months having all my preference files becoming corrupt, this goes against those theories. My macbook has minimal amounts of software installed, and is generally kept quite simple.
Obviously backing up is an important strategy, but that leads to a whole load of decisions like, how often to backup, do you keep incremental backups, do you restore absolutely everything when you discover 1 or 2 corrupt files (how do you know if others have become corrupt?).
Correct shutting down is something I always do - unless something prevents me from doing so, like power cuts. I've also often had a problem with the sccreen remaining blank after macbook has slept or had the screensaver on. On occasion I've had to hold down the power button to shut it down and get it going again.
I've looked into uninterruptible power supplies. Unfortunately, the ideal setup with additional battery to provide a few hours of power are very expensive. Also, should the macbook not be immune from problems caused by power fluctuations because of the battery? I certainly did get a system crash recently when there was a power cut - but at the time I just wondered if it was due to the wireless router going off.
.mac and idisk seem to cause their share of problems. Again, I'm not sure if these are the cause or a consequence of the problems. I have iDisk syncing switched on, and on a few occasions it's vanished and I've had to reboot to get things back to normal. Recently there have been warnings of clashes between .mac and the local idisk.
Filevault is another possible cause of problems. I've read people advising against it's use. However, if someone is willing to steal my macbook, I don't want that sort of person having access to anything, whether it's address book contacts, calendars, word documents or anything financial. OK, people suggest creating an encrypted disk image, but that doesn't solve the problem of preventing people accessing address book or ical.
What I'd really like to know is, what are the main causes of data corruption. If I can identify the causes I might be better prepared for trying to prevent it. For example, if 99% of data corruption is due to power fluctuation then I might accept that I need to spend the money on a UPS.
Once identifying the possible causes, what can be done to prevent them. Would a RAID 1 configuration protect against data corruption, or is it only good in cases of catastrophic drive failure? I've just purchased a 500GB external Firewire 800 drive, which raises the option of creating a RAID 1 with my 2 built in drives.
Sorry for so many questions, but I just really need to get this sorted. Since moving from OS 9 to OS X this has regularly been my biggest cause of troubles.

Answer 1

Hi, bilbo_baggins.
You wrote: "What I'd really like to know is, what are the main causes of data corruption..."You've already identified them, but you seem reluctant to implement the procedures needed to mitigate or avoid those causes that can be mitigated or avoided, in particular:• Power outages or power problems.
• Improper shutdowns.
• Hardware problems or failures, e.g. hard drive failures, bad sectors, bad RAM, etc.
• Bad programming.I can understand your position since:• Not everything one needs to run their computer comes in the box: additional money must be spent.
• The solutions often seem more complex to implement than they really are. One needs some guidance, which again it does not come in the box, and few books address preventing problems before they occur.Here's my advice:
1. Implementing a comprehensive Backup and Recovery Solution and using it regularly is essential to assure against data loss in the event of a hard drive failure or other problems. For advice on the backup and recovery solution I employ, see my "Backup and Recovery" FAQ. Using a personal computer without backup and recovery is like driving without auto insurance. Likewise, without a Backup and Recovery solution, you are accepting the risk of potentially losing all of your data at some point.
2. Perform the little bit of required, regular maintenance: see my "Maintaining Mac OS X" FAQ. It covers my advice on "regular maintenance" and dispels some common "maintenance myths."
3, If you use a desktop Mac, you need an Uninterruptible Power Supply: power outages and other power problems —surges, spikes, brownouts, etc. — can not only cause data corruption but damage your hardware. I have complete advice on selecting a UPS in the "Protecting Against Power Problems" chapter in my book. Don't simply walk into a store and by the first UPS recommended by a clerk: the UPS needs to be configured and sized to match your computer setup. You don't need hours of battery run time: 10-15 minutes is sufficient to save your work and perform a proper shutdown, or for a modern UPS to perform an automatic shutdown if your computer is running in your absence.
4. If you regularly "solve" problems by performing a hard restart (pressing and holding the power button or, on Macs so equipped, the restart button), then go back to work without first troubleshooting the cause of the problem, you risk letting a small problem compound into a larger problem. At a minimum, after a hard restart your should:• Run the the Procedure specified in my "Resolving Disk, Permission, and Cache Corruption" FAQ.
• Then troubleshoot the cause of the problem that led to the hard restart.My book also has an entire chapter on methods for troubleshooting "Freezes and Hangs."
5. Likewise, hoping that by installing a Mac OS X Update will fix a problem, or simply reinstalling one, without first checking for other problems, can make a bad problem worse. Before installing software updates, you may wish to consider the advice in my "Installing Software Updates" FAQ. Taking the steps therein before installing an update often helps avert problems and gives you a fallback position in case trouble arises.
6. FileVault does not corrupt data, but it, like any hard drive or disk imge, doesn't respond well to the causes cited above. This is why it is essential to regularly backup your encrypted Home folder using a comprehensive Backup and Recovery solution. FileVault is an "all your eggs in one basket" solution: if bad sectors develop on the hard drive in the area occupied by your encrypted Home folder, you could lose all the data therein without a backup.
7. RAID: IMO, unless one is running a high-volume transaction server with a 99.999% ("Five Nines") availability requirement, RAID is overkill. For example, unless you're running a bank, a brokerage, or a major e-commerce site, you're probably spending sums of time and money with RAID that could be applied elsewhere.
RAID is high on the "geek chic" scale, low on the "average user" practicality scale, and high on the "complex to troubleshoot" scale when problems arise. The average user is better served by implementing a comprehensive Backup and Recovery solution and using it regularly.
8. I don't use .Mac — and hence, don't use an iDisk — so I can't advise you there. However, I suspect that if you're having problems with these, and the causes are unrelated to issues of Apple Server availability, then I'd suspect they are related to the other issues cited above.
9. You can't completely avoid problems caused by bad programming, but you can minimize the risk by not installing every bit of shareware, freeware, or beta code you read about just to "try it out." Stick to reliable, proven applications — shareware or freeware offerings that are highly rated on sites like MacUpdate and VersionTracker — as well as commercial software from major software houses. LIkewise, a Backup and Recovery solution can help here.
10. Personal computers today are not much more advanced than automobiles were in the 1920's and '30s: to drive back then, you had to be part mechanic as well as driver. Cars today still require regular maintenance. It's the same with personal computers today: you need to be prepared for troubleshooting them (mechanic) as well as using them (driver). Computer hardware can fail, just as autos can break down, usually at the worst possible moment.
People whose homes or offices have several Macs, a network, and the other peripherals normally associated with such setups — printers, scanners, etc. — are running their own data centers but don't know it. Educating yourself is helpful: my "Learning About Mac OS X" FAQ has a number of resources that you will find helpful including books, online training, and more. My book focuses exclusively on troubleshooting, with a heavy emphasis on preventing problems before they occur and being prepared for them should they arise.
Good luck!
Dr. Smoke
Author: Troubleshooting Mac® OS X
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