HP StorageWorks XP Remote Web Console Software - Manual (Page 46)

When the amount of I/Os from the host to the external LU exceeds the maximum amount of I/Os
the external array can accept, commands from the host to the local array might time out. As you
configure the system using external LUs, consider the external array's I/O capacity.
• When executing commands in HP StorageWorks software products to the mapped external LU
and, therefore, too many I/Os are issued for the external array to process, commands might time
out and errors might occur.
When the amount of I/Os from the software products to the external LU exceeds the maximum
amount of I/Os the external array can accept, commands might time out and errors might occur.
As you configure the system using external LUs, consider the external array's I/O capacity.
• When using an external LU from the host, note the external LU's Path Blockade Watch time. If the
Path Blockade Watch time is longer than the host command's timeout period, commands from the
host might time out when the power supply is off or errors occur for the external array. If host I/O
is a significant concern, ensure that the external LU's Path Blockade Watch time is the same as or
shorter than the host command's time-out period.
Combining XP External Storage with other HP StorageWorks
products
You can use HP StorageWorks software products to operate and manage the external LUs you set
using XP External Storage.
The following sections provide configuration examples for specific HP StorageWorks software products:
• Using external LUs for Auto LUN XP operations
• Using external LUs for Continuous Access XP operations
• Using external LUs for Continuous Access XP Journal operations
• Using external LUs for Business Copy XP operations
• Using external LUs for Snapshot XP operations
The following HP StorageWorks software products support the use of mapped external LUs. For
operations and notes about each software product, see the product's user guide.
• XP LUN Configuration and Security Manager Software
• If you set an open-system emulation type when mapping the external LU, you must use XP LUN
Configuration and Security Manager Software to set the mapped LU's path.
• You cannot use the mapped external LU as a NAS system volume.
• You cannot use the mapped external LU as a NAS user volume.
• Volume Manager
• If you set a mainframe-system emulation type when mapping the external LU, you must format
the mapped volume or perform the Write to Control Blocks operation using the Custom Volume
Size (CVS) function before putting the external LU into use. For instructions, see the HP Storage-
Works XP LUN Configuration and Security Manager user guide: HP XP12000 Disk Array, HP
XP10000 Disk Array, HP 200 Storage Virtualization System.
• If you use the CVS function to create LDEVs from an external XP LU, the created LDEVs' attributes
(IO Suppression mode and Cache Mode) are the same as the source external LU's.
• You cannot combine the local array internal LDEV and external LU to form a LUSE volume.
• Do not combine LDEVs of multiple external LUs to create a LUSE volume. You can only use
LDEVs in the same external LU to set LUSE volumes.
• You cannot combine external LUs that have different IO Suppression modes to form a LUSE
volume.
Preparing for XP External Storage operations 46