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Back Up Important Data!

Chapter 2, “Before You Install or Upgrade,” emphasized that before you attempt to perform an upgrade to Windows XP, you should first perform a backup of the system or at least the data files. Back up those files as well as any other files you may need to restore the system in the case of a problematic failure. Although modern PCs can be very reliable, anything can happen that may cause a loss of data. This is especially true for users of Windows XP. Many redundant capabilities like the feature called redundant array of inexpensive disks (RAID) are not often found on a personal computer. These expensive techniques are usually reserved for high-end servers.

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Redundant Array of Inexpensive Disks (RAID). This term was conceived back when large computer servers used much more expensive disks than the ones installed on today's PCs. Now, the term stands for Redundant Array of Independent Disks, since they aren't necessarily inexpensive anymore, and RAID is not just a single technology. It comes in all sizes and types. For example, disk striping—which uses a set of disks as if they were a single disk and divides up disk writes and reads so that data gets stored in “chunks” across multiple disks—can improve read or write performance, since more than one disk is at work storing a smaller portion of the input and output (I/O).

Other techniques were developed over the years, such as adding a parity stripe to allow for the continued operation and recovery if a single member of a striped disk set was lost. Additionally, disk striping is referred to as RAID level 0. Disk mirroring is known as Raid level 1 and is simply a technique where the disk controller writes the same information to two or more disks. This way, if one disk becomes defective, the other has a complete copy. There are other RAID levels, and readers are encouraged to research the topic further. Several Web sites explain the basic RAID techniques in use today.



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