Книга: Fedora™ Unleashed, 2008 edition

Why Data Loss Occurs

Why Data Loss Occurs

Files disappear for any number of reasons: They can be lost because the hardware fails and causes data loss; your attention might wander and you accidentally delete or over write a file. Some data loss occurs as a result of natural disasters and other circumstances beyond your control. A tornado, flood, or earthquake could strike, the water pipes could burst, or the building could catch on fire. Your data, as well as the hardware, would likely be destroyed in such a disaster. A disgruntled employee might destroy files or hardware in an attempt at retribution. And any equipment might fail, and it all will fail at some time — most likely when it is extremely important for it not to fail.

Data can also be lost because of malfunctions that corrupt the data as it attempts to write to the disk. Other applications, utilities, and drivers might be poorly written, buggy (the phrase most often heard is "still beta quality"), or might suffer some corruption and fail to correctly write that all-important data you just created. If that happens, the contents of your data file would be indecipherable garbage, of no use to anyone.

All these accidents and disasters offer important reasons for having a good backup strategy; however, the most frequent cause of data loss is human error. Who among us has not overwritten a new file with an older version or unintentionally deleted a needed file? This applies not only to data files, but also to configuration files and binaries. Among users perusing the mail lists or the Usenet newsgroup postings, stories about deleting entire directories such as /home, /usr, or /lib seem all too common. Incorrectly changing a configuration file and not saving the original in case it has to be restored (which it does more often than not because the person reconfigured it incorrectly) is another common error.

Proper backups can help you recover from these problems with a minimum of hassle, but you have to put in the effort to keep backups current, verify their intactness, and practice restoring the data in different disaster scenarios.

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