About RAID
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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.
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.
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.
Drawbacks
RAID 5 has the combined drawbacks of RAID 0 (one drive completely failing
results in total data loss) and and RAID 1 (array 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.