AMCC 3WARE 720-0138-00, Installation Manual

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Determining What RAID Level to Use
www.3ware.com 31
For additional information about RAID levels, see the article
“RAID Primer” on the 3ware website, at: http://www.3ware.com/
products/pdf/RAID_Primer.pdf.
Other Important Concepts
„
Write Cache
. Used to store data locally on the drive before it is
written to the disk, allowing the computer to continue with its
next task. Enabling write cache results in the most efficient
access times for your computer system. However, there may be
instances when you always want the computer to wait for the
drive to write all the data to disk before going on to its next
task. In this case, you must disable the write cache.
Determining What RAID Level to Use
The RAID configurations available to you are determined by the
number of ports on your controller, and the number of drives
attached to those ports. You can configure all drives in one array, or
you can configure multiple arrays, if you have enough drives.
Table 1: Possible Configurations Based on Number of Drives
# Drives
Possible Configurations
1 Single drive or hot spare
2 RAID 0 or RAID 1
3 RAID 0
RAID 1 with hot spare
RAID 5
4 RAID 5 + hot spare
RAID 10
Combination of RAID 0, RAID 1, single disks