Hp XP External Storage Software Manual de usuario descargar pdf (Pagina 22)

You need to assign numbers to external volume groups. See “External Storage Requirements” on page 43

for details on a maximum number of external volume groups, or a maximum number of volumes to be

registered in one external volume group.

Conﬁguring Ex

ternal Volume Attributes

When you map an

external volume as an internal volume, you set the attributes of the external

volume. External volume attributes can be set using the mapping policy or the Set External

Volume Parameter dialog box of the External Storage. For details on the mapping policy, see

“Choosing Mapping Policy” on page 30. For details on the Set External Volume Parameter dialog box,

see “Set Exte

rnal Volume Parameter Dialog Box” on page 72.

The attribut

es of the external volume are as follows:

• Emulation type

Select an emulation type for the mapped external volume from the drop-down list.

The emulatio

ntype OPEN-V must be selected if, after the mapping, you are planning to use the

existing dat

a in the external volume from the local storage system. For example, if you want to

migrate the existing data in the external volume to the local storage system volume, you have to

set the OPEN-V emulation type when the external volume is mapped.

If you selec

t the emulation type other than OPEN-V,the volume requires aspeciﬁcareaprovided

for management data. Once this area is provided, volume capacity after the mapping becomes

less than the actual external volume capacity for the area (volume). For details on volume

capacity, see “Capacity Guidelines”onpage45.

• Cache Mode

(Enable or Disable)

Cache mode speciﬁes whether the write data from the host to the external storage system is

propagated synchronously or asynchronously. All I/O to and from the local storage system (either

Enable or Disable) always uses cache. Write operations are always backed up in duplex cache.

•If you sel

ect Enable, after receiving the data into the local storage system cache memory,

the local

storage system signals the host that an I/O operation has completed and then

asynchronously destages the data to the external storage system cache where it is then

asynchronously destaged to disk.

•If you se

lect Disable, the local storage system signals the host that an I/O operation has

complet

ed only after the local storage system has synchronously written the data to the

external storage system cache. The external storage system cache then asynchronously

destages this data to disk.

If you perform the HP StorageWorks XP Cache Residency Manager operation on the external

volume, which the Cache Mode is set to Disable, the bind mode of Cache Residency Manager

cannot be speciﬁed. For the Cache Residency Manager operation, see the HP StorageWorks

XP240

00 Cache Residency Manager User’s Guide.

• Inﬂow Control (Enable or Disable)

Inﬂow control speciﬁes whether the writing operation to the cache memory is stopped (Enable)or

continued (Disable) when the writing operation to the external volume is impossible. By default,

inﬂow control is set to Disable

•If yo

uselect Enable,the writingoperation to cacheisstoppedand theI/O from thehostisnot

accepted when the writing operation to the external volume is impossible.

•If you select Disable, the I/O from the host during the retry operation is written to the cache

memory even after the writing operation to the external volume is impossible. Once the

wri

ting operation to the external volume becomes normal, all the data in the cache memory

is written to the external volume (all the data is destaged).

• CLPR

Whe

n the cache memory is partitioned using HP StorageWorks XP Disk/Cache Partition,

con

ﬁgure a cache logical partition (CLPR) to access the mapped volume. Please see the HP

orageWorks XP24000 Disk/Cache Partition User’s Guide for the detailed information on CLPR.

About External Storage Operations

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