HP StorageWorks External Storage XP user guide (T1706-96006, June 2006)

32 Preparing for External Storage XP operations
Limitations on External Storage XP operations
• External LUs can be mapped as any CU:LDEV combination from 00:00 to 3F:FF.
• Only ports in SLPR0 can be set as external ports.
• Do not access any external storage volume that is mapped as an External Storage XP volume from a
host connected directly to the external array. Also, do not access an External Storage XP mapped
external array volume using the external array’s functions (for example, local replication). After
mapping an external disk volume as a local array volume, access the mapped external disk volume
only via the local array.
• Except on the MSA, a host can directly access external array volumes that have not been mapped as
local array volumes.
• Continuous Access XP P-VOLs, S-VOLs, and journal volumes are not supported on MSA arrays.
• HP does not recommend that volumes involved with Snapshot XP reside on external MSA arrays.
• If you map an external LU that is more than 2 TB with the setting of OPEN-V emulation type, you can
access data stored in the field up to 2 TB. You cannot access data stored in the field over 2 TB.
• When mapping a volume that has a capacity of 2 TB or less in the external array and (external LU)
with the OPEN-V emulation type, the LU is defined as an internal LDEV with the same capacity as the
mapped external LU. That is, no space is forfeited for management space, and no formatting of that
data occurs. Therefore, OPEN-V is recommended.
Figure 11 Example of external LU with 2 TB or less
• If you map an external LU that is equal to or greater than 575.98 GB with an OPEN emulation type
other than OPEN-V, you can access data stored in the field up to 575.98 GB. You cannot access data
stored in the field over 575.98 GB.
However, for emulation types with a small base capacity, some of the field of 575.98 GB might not
be available. For more information, see ”Required volume capacity for emulation types” on
page 141.
• If you map an external LU that is equal to or greater than 575.98 GB with a 3380 mainframe
emulation type, you can access data stored in the field up to 575.98 GB. You cannot access data
stored in the field over 575.98 GB.
However, for emulation types with a small base capacity, some of the field of 575.98 GB might not
be available. For more information, see ”Required volume capacity for emulation types” on
page 141.
• If you map an external LU that is equal to or greater than 695.98 GB with a 3390 mainframe
emulation type, you can access data stored in the field up to 695.98 GB. You cannot access data
stored in the field over 695.98 GB.
However, for emulation types with a small base capacity, some of the field of 695.98 GB might not
be available. For more information, see ”Required volume capacity for emulation types” on
page 141.
• If you plan to use the mapped external LU from the mainframe OS (volume is mapped with a 3380-x
or 3390-x mainframe emulation type), you must select an external LU that consists of one LDEV or you
must first adjust the capacity of the external LU to be mapped. If multiple LDEVs exist in one external LU
and if numerous I/Os are made to these LDEVs, the read and write commands might timeout. When
the commands timeout, the SIM (21D2xx) is reported.
• When mapping an external LU as internal LDEVs with emulation types other than OPEN-V, the number
of volumes and the volume capacity of the mapped internal LDEVs depends on the original external