HP XP External Storage Software - Manual (Page 20)

This document sometimes uses the term external volume or mapped external volume to mention an
internal volume where an external volume is mapped (see B in Figure 4 on page 19), because this
internal volume is a virtual representation of an external volume.
When you perform mapping, a path is automatically created between an internal volume and an
external volume. This path is called a mapping path, which connects one volume with another volume. A
cross-subsystem path is a part of a mapping path.
To use the external volumes, which you mapped as an internal volume (see B in
Figure 4 on page 19),
from the host or other program products, the system administrator needs to create LDEVs in the external
volume (see A in Figure 4 on page 19). To create LDEVs, use External Storage at the time of mapping, or
use VLL function to an internal volume where an external volume is mapped after mapping. The LDEVs
created by these methods are called LDEVs in the external volume in this document. These LDEVs are
usually called external volumes in other documents.
An external volume corresponds to a VLL VDEV (Virtual Device). An LDEV in the external volume
corresponds to a VLL LDEV. Therefore, you can use VLL function to create custom-sized volumes in an
external volume after mapping, in the same way as creating custom-sized volumes in the normal internal
volumes. For details on VDEVs and LDEVs, see the HP StorageWorks XP24000 Virtual LVI/LUN (VLL)
and Volume Shredder User’s Guide.
External Storage Operations
External Storage enables you to execute the following operations.
• Preparing to use external volumes
You can map external volumes, set port attributes, and set cross-subsystem
paths. For details, see “ Configuring External Storage ” on page 20, and section
“ Overview of Setting Operations ” on page 67.
• Preparing to manipulate the power supply of the storage systems
You must follow specific procedures if you want to manipulate the power supply of the storage
systems when external volumes are used. To turn on or off the power supply of the external
storage system after starting to use the external volumes, you need to execute the commands of
External Storage. For details, see “ Turning On or Off the Storage System ” on page 87.
• Setting up and removing the cross-subsystem paths
When you set up or remove the path (cable) connecting the storage systems, you need
to use External Storage to make settings on the path. For details on removal, see
“ Disconnecting External Storage System or Disconnecting External Volume ” on page 89 and
section “ Checking Connection Status and Resuming External Volume Operation ” on page 91. For
details on setup, see “ Configuring Cross-subsystem Path ” on page 81.
• Referring to the status of external volumes
You can see the status and the configuration of external volumes. For details, see
“ Checking the External Volume Details ” on page 83.
• Stopping the use of external volumes
You can cancel mapping of external volumes. For details, see
“ Deleting the External Volume Mapping ” on page 96.
• Setting the remote command device
By using the remote command device, you can manipulate volumes in the external storage
system from the HP StorageWorks XP RAID Manager on host computers. For details, see
“ Remote Command Devices ” on page 99.
Configuring External Storage
Before configuring the External Storage settings, you need to answer the following:
• Which ports can be connected to external storage systems (see
“ Choosing the External Port ” on page 21).
• Which external storage system and volumes should be mapped as the internal volumes (see
“ Choosing and Mapping External Volumes ” on page 21).
20 About External Storage Operations