Apple Tested Apple Certified Apple Certified Technical Coordinator for Mac OS X v 10.3, 10.2, and 10.1 Apple Certified Help Desk Specialist for Mac OS X v 10.3		Why You Will Lose Your Data by Fred Balin Created: July 6, 2001 Latest Modification: June 6, 2004 It has been said that there are two types of computer users: those who have lost data and those who are about to. Here's why.   1. Head Crashes Hard drives are finely-tuned, precision, electromechanical devices. A series of platters with magnetic coatings spin at a rate of between four and ten thousand revolutions per minute. Surrounding each platter is a pair of heads connected to an armature. The heads whiz in and out at speeds of over 60 miles per hour and read to and write from the platters. Space is incredibly tight. The heads operate at a distance of less than the width of a human hair off the surface of the platters. When the drive spins down or is turned off, the heads park in a special landing area. They do not touch the data surface of the moving platters,....unless there is a head crash. If so, it can be a bad scene. Marks are made on the surface of platters and debris starts flying, which can cause more damage. Head crashes can occur without warning and put your data at grave risk. Hard drive manufacturers often provide a bogus means of reliability, such as a Mean Time To Failure (MTTF). The 20GB Toshiba hard drive in my PowerBook for instance has an MTTF rating of 300,000 hours, or 34 years. Sounds nice, but its not valid. The manufacturers have no way of knowing when their drives will fail, because they don't run them long enough. In fact, in late 2002 hard drive manufacturers, scaled back the many drive warranties from 3 yeas to 1, a indication that drives are failing more frequently andsooner thant prediced. The bottom line from this quarter is that drives can fail at any time, and I don't recommend keeping a frequently-used drive over four years.   2. Power Outages and Surges A power outage will cause you to lose any data since the last time you saved to disk. A bigger concern may be when the power comes back on. Like an uneven flow of rusty water coming through old pipes in the morning, electric power may not come back on in an even manner after an outage. Overvoltages can damage the circuit board on your hard drive and other components of your system. Use a quality surge protector (i.e. UL 1440 / 330 V rated) or an uninterruptible power supply to protect you.   3. PowerBook Jitters Hard drives are prone to damage from rough handling. When you carry your PowerBook around, it's best to keep it in a special carrying case with protective padding and/or a protective flexible sling. If you need to move your PowerBook from one place to another while it's on, put the system to sleep to spin down the drive and park the drive heads.   4. Zip Friction and "The Click of Death" Zip disk technology is closer to that of a floppy disk than to a hard drive. On a Zip drive-and-disk combo the heads make contact with the platter, a reason why floppies and Zips often wear out sooner than hard disks. When a Zip is placed in its drive, the heads go first to a special sector on the disk that contains the Master Directory Block, which holds key disk bookkeeping information. If this block wears out through excessive use, the drive head keeps trying over and over again to access it, hence a repeating "click, click, click," a sign of the infamous Zip "click of death." A worn out Master Directory Block on a Zip disk not only causes you to lose access to your data but the repeated attempts to access it can damage your Zip drive, in turn causing damage to other disks. Yes, The Click of Death can be contagious. If you experience these continuous clicks, remove the disk and use a brand new Zip disk to test the drive's mechanism. To help prevent this problem, replace frequently-used Zip disks every few months.   5. Goof Ups Have you ever accidentally deleted a file you needed? Did you ever mistakenly save or copy a file or folder over another one with the same name? Have you ever reformatted the wrong hard disk volume? If you answered "yes" to any of the preceding, pat yourself on the back, you're human.   6. Directory Corruption Crashes and software bugs can cause small errors in a drive's directory. The directory is the drive's table of contents to your files. Over time, if directory problems are not fixed, you may lose access to some or all your files. As part of a periodic maintenance, make sure you regularly use utility software to deal with directory corruption. These programs can include Disk First Aid, Norton Utilities, Tech Tool Pro, and my favorite for directory corruption, Disk Warrior. Disk Warrior under OS 9, by the way, in addition to repairing directory damage, can prevent it through the use of an extension that checks your directory for problems before writing to it.   7. Computer Viruses Viruses are relatively rare on the Mac side of the computer divide, but they occasionally appear and can destroy data. If you regularly receive disks or attachments from other users, I recommend you get Norton AntiVirus (now also part of Norton SystemWorks), run the program, and use its Live Update feature each month to download the latest antivirus definitions.   8. Theft and Vandalism A print shop I work with recently had a break in. Their new production PowerMac G4, software disks, and backup disks were taken. Some data was resurrected from another machine, but a lot was lost. Ouch!   9. Natural Disasters Flooding, earthquakes. Yes, this is California.   So how do you best protect your valuable and fragile data. Back up regularly to removeable media; rotate the media, and keep a copy off site. We will devote a forthcoming special report to this topic. Institute a process of regular maintenance to keep your system running smoothly. Clean directories, purge viruses, rebuild desktops, disable unneeded third-party system startup files, and maintain adequate free unfragmented hard disk space.
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