Configuring A Storage Subsystem; Determining What Is On Your Storage Subsystem - IBM System Storage DS3000 Programming Manual

might use the same LUN to access different logical drives. The LUNs might be the same, but the logical
drives are different. If you are mapping to a host group, the LUN that you specify must be available on
every host in the host group.

Configuring a Storage Subsystem

When you configure a storage subsystem, you want to maximize the data availability by making sure
that the data is quickly accessible while maintaining the highest level of data protection possible. The
speed by which a host can access data is affected by these items:
v The RAID level for the subsystem
v The settings for the segment size and the cache size
v Whether the cache read prefetch capability is turned on or turned off
Data protection is determined by the RAID level, hardware redundancy (such as global hot spares), and
software redundancy (such as the Enhanced Remote Mirroring premium feature and the FlashCopy
Logical Drive premium feature).
In general, you configure a storage subsystem by defining an subsystem and its associated RAID level,
defining the logical drives, and defining which hosts have access to the logical drives. This section
explains how to use the script commands to perform the general steps to create a configuration from an
subsystem of disk drives.

Determining What Is on Your Storage Subsystem

Even when you create a configuration on a storage subsystem that has never been configured, you still
need to determine the hardware features and software features that are to be included with the storage
subsystem. When you configure a storage subsystem that has an existing configuration, you must make
sure that your new configuration does not inadvertently alter the existing configuration, unless you are
reconfiguring the entire storage subsystem. For example, consider the case where you want to create a
new subsystem on unassigned disk drives. Before you create a new subsystem, you must determine
which disk drives are available. The commands that are described in this section help you to determine
the components and the features in your storage subsystem.
The command that returns general information about the storage subsystem is the show
storageSubsystem command. This command returns information about the components and properties of
your storage subsystem, including these items:
v A detailed profile of the components and features in the storage subsystem
v The age of the battery
v The default host type (which is the current host type)
v Other host types that you can select
v The hot spare locations
v The identifiers for enabled features
v The logical component profiles and the physical component profiles
v The time to which both controllers are set
v The controller that currently owns each logical drive in the storage subsystem
To return the most information about the storage subsystem, run the show storageSubsystem command
with the profile parameter. This example shows the complete CLI command and script command
running on a Windows operating system:
c:\...\...\client>smcli 123.45.67.89 -c "show storageSubsystem profile;"
This example identifies the storage subsystem by the example IP address 123.45.67.89. You can also
identify the storage subsystem by name.
4-17
Chapter 4. Configuring a Storage Subsystem