Connecting Open Systems Volumes - HP StorageWorks XP24000 User Manual

For the volume formatting and Write to Control Blocks operation procedures, see the HP
StorageWorks XP24000/XP20000 Virtual LVI/LUN (VLL) and Volume Shredder User Guide.

Connecting Open Systems Volumes

Open systems volumes in external storage system connect to and are recognized by the storage
system as open systems volumes, without requiring reformatting. Reformatting is not required
because the connection between the storage system and the external storage system is Fibre
Channel. If you need to initialize the data area for the volume, format the volume using the VLL
function. For the volume formatting operation procedure, see the HP StorageWorks
XP24000/XP20000 Virtual LVI/LUN (VLL) and Volume Shredder User Guide.
OPEN-V emulation is recommended because, in most cases, OPEN-V emulation provides the most
efficient use of storage and the best performance. Also, emulation types other than OPEN-V may
not retain existing data after being mapped.
Choosing Mapping Policy
Mapping policy is a list of settings of the necessary information for mapping the external volume.
By setting the mapping policy in advance, the setting at the time of mapping will be easier.
The default mapping policy is prepared in advance. You can change the values of the default
mapping policy.
Difference between Automatic Mapping and Manual Mapping
When you map the external volume, you need to configure:
Cross-subsystem paths
External volume parameters
LDEV number to LDEVs in the external volume
SSID (storage system ID)
When you perform automatic mapping, users configure only cross-subsystem paths and all the
other settings are automatically made by XP External Storage according to the mapping policy.
When you perform manual mapping, users configure all the settings.
Automatic mapping maps all the external volumes found by volume discovery to internal volumes.
Automatic mapping requires fewer settings but you are not allowed to set different parameters for
each external volume or to specify an LDEV number for each LDEV. You can set the parameters
such as emulation type to the mapping policy in advance.
NOTE: In automatic mapping, external volumes are mapped in the order of the local storage
system recognizing. Therefore, the LDEV number is also specified in this order. Moreover, when
you copy external volumes with the program product for copying, the copy operation is performed
in the order of the LDEV number if you specify two or more external volumes for the initial copy or
resynchronization. Therefore, when you copy external volumes that are mapped automatically with
the program product for copying, the copy operation might focus on a specific RAID group and
cause insufficient performance. To prevent the copy operation from focusing on a specific RAID
group, HP recommends that the external volumes be mapped manually so that the copy operation
is distributed to two or more RAID groups.
Port Discovery and Volume Discovery
Port discovery and volume discovery are methods used to find external volumes, and are executed
when you map external volumes or when you add cross-subsystem paths.
Port discovery searches for and gets information about target ports of the connected external
storage system from an external port of the local storage system. The latest information about
HP Confidential Choosing Mapping Policy 25