Reconfiguring The Array Settings; Unit Volume Configurations - Sun Microsystems Sun StorEdge T3 Installation, Operation And Service Manual

3.2

Reconfiguring the Array Settings

The array is set with the following default configuration:
RAID 5 volume; no hot spare
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Cache mode set to auto
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Autodisable and autoreconstruction of disk drives
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These default settings and other possible configurations are described in the
following sections. Refer to the Sun StorEdge T3 and T3+ Array Administrator's Guide
for instructions on how to change the array default settings.
Some of the terminology used in this chapter is defined as follows:
Volume, also known as a logical unit number (LUN), is the basic structure you
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create across the drive group to retrieve and restore data. A volume is a set of
physical drives that has been configured into RAID level 0, 1, or 5.
Hot spare is a drive containing no data that acts as a standby in case another drive
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fails in a RAID 1 or 5 volume. The hot spare drive adds another level of
redundancy: if a drive fails, the hot spare takes over for the failed drive until you
replace it. When you replace the failed drive, data from the hot spare is copied
back to the replaced drive and the hot spare returns to a standby status.
Parity is additional information stored along with the data that enables the
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controller to rebuild data after a drive failure. Only RAID 5 volumes have parity.
RAID 1 uses mirroring, not parity, which enables the controller to reconstruct data
after a drive failure.
3.2.1

Unit Volume Configurations

The drives in an array unit can be grouped into one or two volumes (LUNs). The
minimum number of drives to compose a volume is two; the maximum is nine. A
hot spare drive can be configured in the unit as an option. If you are configuring a
hot spare in the volume, you can use only drive 9 in the array as a hot spare. You can
have only one hot spare per array, which can be shared by two volumes.
If you choose to include a hot spare disk drive in your configuration, add it when
you initially create the volume. If you want to add a hot spare at a later date, you
must remove the existing volume and re-create the configuration.
You can also configure the two volumes into smaller partitions or combine multiple
volumes into a single volume by using specialized third-party software such as
VERITAS Volume Manager.
Chapter 3 Operation 3-3