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About RAID
RAID for performance
About RAID
RAID (Redundant Array of Inexpensive/Independent Disks) lets your computer use
multiple hard drives more efficiently. Your computer supports RAID 0, RAID 1,
RAID 5, and RAID 10.
RAID 0 lets your computer see multiple hard drives as a single drive. This type
of RAID can increase file access speeds, which is important if you work with
video editing, sound editing, and high-performance games. RAID 0 is also an
affordable way to increase your total file storage capacity.
How it increases performance
The more drives you have in your RAID 0 array, the faster the potential drive
reading performance. All hard drives have limitations on how fast they can read
and write files. If half a file is stored on one RAID 0 drive and the other half on
another RAID 0 drive, each drive only has to read half of the file. So, the entire
file is accessed by the computer up to twice as fast (using a two-drive RAID 0
array). In a three-drive RAID 0 array, if the file is evenly distributed among the
drives, each drive must read only a third of the file, and so on. If the entire file
happens to be stored on only one of the drives, the file is accessed at the same
speed as if it were on a standard hard drive setup. Dividing up files between
multiple hard drives like this is called striping.
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.
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About RAID www.gateway.com
RAID for security
RAID 1 maintains a complete copy of a file set on each physical hard drive in
the array. Because each hard drive has a full copy of all files, your data and
applications are completely backed up. 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.
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.
For maximum reliability, you can use a separate hard drive controller for each
drive (called splitting or duplexing).
Drawback
RAID 1 treats the entire array as a single drive with the storage capacity of the
smallest physical drive in the array. So if you have three drives (300 GB, 250 GB,
and 200 GB) in a RAID 1 array, your computer only recognizes a single drive with
200 GB total capacity.
RAID for both: performance and security
RAID 5 uses mirroring across the drives, and striping (at the block level) with
on-the-fly error correction across all drives. Because of this error correction,
small file read/write errors can be quickly and automatically fixed without a
significant drop in system performance. RAID 5 offers good performance and
data redundancy. This array preserves your files if a drive fails.
RAID 10 (also called RAID 1+0 or RAID 1&0) contains sets of RAID 1 mirrors acting
as drives within a RAID 0 striping array. With this setup, all but one drive in the
array can fail, and the RAID would still be providing necessary data to the
computer.
Drawback
A RAID 5 array is treated as one drive with capacity of smallest physical drive.
RAID 10 treats the entire array as a single drive with the storage capacity of the
smallest drive in the array. So if you have four drives (350 GB, 300 GB, 250 GB,
and 200 GB) in a RAID 10 array, your computer only recognizes a single drive
with 200 GB total capacity.
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