Silicon Graphics InfiniteStorage 4000 Series, Настройка и обслуживание

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Chapter 4: Configuring a Storage Array 63
When the controller firmware assigns the drives, if
trayLossProtect
=
TRUE
, the
storage array posts an error if the controller firmware cannot provide drives that result
in the new volume group having tray loss protection. If
trayLossProtect
=
FALSE
, the storage array performs the operation even if it
means that the volume group might not have tray loss protection.
Tray loss protection is not valid when creating volumes on existing volume groups.
Configuring a
Storage Array
with Disk Pools A disk pool is a collection of 11 or more drives in a storage array that have the same
spindle speed, the same security level, and preferably the same capacity to make the
most efficient use of the drives.
A storage array can contain one or more disk pools, although the benefits of using a
disk pool increase as the number of drives in a disk pool increase. Creating a disk pool
with the largest number of similar drives is the preferred approach. However, if not all
drives in the storage array have the same characteristics or if you want certain drives
to support different applications, you can create more than one disk pool on your
storage array. There is no practical limit on the number of drives that can comprise a
disk pool, although a disk pool cannot contain more drives than the maximum limit
for each storage array.
Two differences between setting up a disk pool and a volume group are that with a
disk pool the RAID level is preset to RAID 6 and there is no need to designate a hot
spare drive. In a disk failure condition in a disk pool, instead of using hot spare
technology all the operational drives in the disk pool participate in the reconstruction
process. The reconstruction data space is used to reconstruct the data from the failed
drive. With a volume group, hot spare technology is used to recover from a drive
failure condition and you select the RAID level during the configuration process.
In general, you configure a storage array by defining a disk pool, the volumes, and
which hosts have access to the volumes. The following sections explains how to use
the script commands to perform the general steps to create a disk pool configuration
from an array of drives.
You can have two types of volumes in a disk pool:

Standard volume
A standard volume has a fixed capacity that you can define when you create the
volume.

Thin volume
A thin volume is an expandable volume with both physical capacity and virtual
capacity.