3Ware 9550SX-4LP User Manual page 139

a Unit" on page 157.) If drives are listed under "Incomplete Drives and
Others," they must be deleted before they can be used.
If you want to add drives to be used in the unit, see "Adding a Drive through
3DM" on page 168.
Type of configuration
Available configuration types include RAID 0, RAID 1, RAID 5, RAID 10,
RAID 50, and Single Disk. For information about the different RAID levels,
see "Understanding RAID Concepts and Levels" on page 5.
Name of the unit (optional)
Units can be given names. These names will be visible in 3DM, 3BM, and
CLI.
Stripe size, if appropriate for the RAID level
In general, smaller stripe sizes are better for sequential I/O, such as video, and
larger stripe sizes are better for random I/O (such as databases).
Striping size is not applicable for RAID 1, because it is a mirrored array
without striping.
Using the default stripe size of 64KB usually gives you the best performance
for mixed I/Os. If your application has some specific I/O pattern (purely
sequential or purely random), you might want to experiment with a smaller or
larger stripe size.
Unit policies
Several unit policies are set when you create a new unit:
• Write Cache (enabled, by default)
• Drive Queuing (disabled, by default). Available only for 9550SX and
9590SE controllers.
• Auto-Verify (disabled, by default)
• Continue on Source Error When Rebuild (disabled, by default).
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Note: Creating a unit erases all data on all drives. Although
creating a RAID 1 (mirror) creates a unit that will have a duplicate
of data on both drives after it is put in use, creating a RAID 1
cannot be used to make a backup copy of data that currently exists
on a single drive unless you migrate from a RAID 1 to two
individual single disks.
Configuring a New Unit
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