Gateway FX540, Справочное руководство, Страница: 48 / 164

CHAPTER 4: Advanced Hardware Setup
42
How it makes file storage cheaper
Because RAID 0 lets your computer see multiple hard drives as
a single drive, you can install several lower capacity (less
expensive) drives and have the same single-drive storage
simplicity and capacity as a larger, more expensive hard drive.
Drawbacks
Unfortunately, RAID 0 lets multiple drives behave as one in
another way. If part of the array fails (such as a hard drive
crashing), the entire array fails. Because the drives are treated
like a single drive, parts of files (including operating system
files) can be spread across several drives, leaving the computer
with only file fragments if one drive fails. Regular and frequent
backups are critical.
Another drawback is that RAID 0 treats each hard drive as if it
has the storage capacity of the smallest drive in the array. So
if you have three drives (300 GB, 250 GB, and 200 GB) in a
RAID 0 array, your computer only recognizes 600 GB total
capacity.
RAID 1 for security
RAID 1 maintains a complete copy of all files on each physical
hard drive in the array. Maintaining simultaneous, complete
copies of files across multiple hard drives is called mirroring.
If a drive fails, the mirrored drive takes over and acts as the
primary drive.
In the following graphic, each letter represents a unique block
of data, and each column represents a separate hard drive.
File reading performance (seek time) is increased using the
same methods that RAID 0 uses, although writing speed is the
same as if writing to a single hard drive.
A
B
C A
B
C
RAID 1
8512728.book Page 42 Wednesday, September 19, 2007 3:44 PM