User`s guide

User Guide
75
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Warning:
•
RAID1 reads or writes data to/from the several hard disk drives at the
same time. The disk access performance is lower than the single disk.
• Logical capacity of the array is equal to one hard disk drive connected.
Raid 10 & RAID 5
These RAID levels may also be available on your system. Browse through the next
sections of this User’s Guide for more information.
■ RAID 10
Mirror/Stripe combines both of the RAID 0 and RAID 1 logical drive types. It can
increase performance by reading and writing data in parallel while protecting data
with duplication. At least four disk drives are needed for RAID 10 to be installed.
With a four-disk-drive logical drive, one drive pair is mirrored together then
striped over a second drive pair.
The data capacity is similar to a RAID 1 logical drive, with half of the total storage
capacity dedicated for redundancy. An added plus for using RAID 10 is that, in
many situations, such a logical drive offers double fault tolerance. Double fault
tolerance may allow your logical drive to continue to operate depending on which
two disk drives fail.
■ RAID 5
RAID level 5 organizes data across the disk drives of the logical drive, and
distributes parity information across the disk drives along with the data blocks.
This organization allows increased performance by accessing multiple disk drives
simultaneously for each operation, as well as fault tolerance by providing parity
data. In the event of a disk drive failure, data can be re-calculated by the RAID
system based on the remaining data and the parity information.
The adjustable block size of the RAID 5 logical drive allows for performance
tuning based on the typical I/O request sizes for your system. The block size must
be set at the time the logical drive is created and cannot be adjusted dynamically.
RAID 5 makes efficient use of hard drives and is the most versatile RAID Level. It
works well for file, database, application and web servers.
The capacity of a RAID 5 logical drive is the smallest disk drive size multiplied by
the number of disk drives, less one. Hence, a RAID 5 logical drive with four 100
GB disk drives will have a capacity of 300 GB. A logical drive with two 120 GB
disk drives and one 100 GB disk drive will have a capacity of 200 GB.