HP StorageWorks External Storage XP user guide for the XP12000, XP10000, SVS200 (T1706-96009, October 2007)

• IfthehostconnectedtothelocalarrayissuestoomanyI/Osfortheexternalarraytoprocess,
commands from the host might time out.
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.
• WhenexecutingcommandsinHPStorageWorkssoftwareproductstothemappedexternalLU
and, therefore, too many I/Os are issued for the external array to process, commands might time
outanderrorsmightoccur.
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 timeout period.
• Host access to the external storage LU must be via the local array, and must not beviaadirect
physical connection to the external storage device LU. For external array LUs not involved with
External Storage XP, direct access from a host is allowed for all supported external storage except
MSA.IfyouuseMSAasexternalstorage,itmustbeentirelydedicateasexternalstorage.
• For all external storage, either set the ES XP cache mode option in Command View XP or XP
Remote Web Console to cache disabled or partition resources associated with external storage
in its own CLPR (for example, CLPR1). While HP strongly recommends this new default for all
external storage in general, this new default is mandatory for any external array that is slower
than an XP12000 external port (for example, the Modular Smart Array product line) unless it
resides in its own CLPR partition with isolated port/MP/cache resources.
Combi
ning External Storage XP with other HP StorageWorks
produ
cts
You c
an use HP StorageWorks software products to operate and manage the external LUs you set
using External Storage XP.
The following sections provide configuration examples for specific HP StorageWorks software products:
• Using external LUs for Auto LUN XP operations
•Usin
g external LUs for Continuous Access XP operations
• Using external LUs for Continuous Access XP Journal operations
• Using external LUs for Business Copy XP operations
•Usi
ng external LUs for Snapshot XP operations
The
following HP StorageWorks software products support the use of mapped external LUs. For operations
an
d notes about each software product, see the product's user guide.
• LUN Manager
• If you set an open-system emulation type when mapping the external LU, you must use LUN
Ma
nager 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.
• V
olume 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 StorageWorks LUN Configuration and Security Manager XP user guide for the
XP12000/XP10000/SVS200.
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Preparing for External Storage XP operations