HP XP20000 Bedienungsanleitung PDF herunterladen (Seite 18)

set to Disable. All I/O to and from the local storage system (either Enable or Disable) always

uses cache mode. Write operations are always backed up in duplex cache.

◦ If you select 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.

◦ When emulating OPEN volumes and selecting Disable, the local storage system signals

the host that an I/O operation has completed only after the local storage system has

synchronously written the data to the external storage system. When emulating mainframe

volumes, when you select Disable, 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.

If you perform the Cache Residency Manager operation on an external volume with

Cache Mode set to Disable, the bind mode of Cache Residency Manager cannot be

specified. For Cache Residency Manager operations, see the HP StorageWorks

XP24000/XP20000 Cache Residency Manager User Guide.

When you set the cache mode, note the following:

◦ Data that is not written by the host (for example, data written by HP StorageWorks XP

Continuous Access Software) is asynchronously destaged to the external storage system

regardless of the Cache Mode setting.

◦ If you set the emulation type for a mainframe system (such as 3390-x), data that is written

by a host using a command such as Format Write is asynchronously destaged to the

external storage system regardless of the Cache Mode setting. Data that is written by a

host using a command such as Update Write is destaged to the external storage system

as configured in the Cache Mode setting.

• 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 you select Enable, the writing operation to cache is stopped and the I/O from the host

is not 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 writing 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

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

Software, configure a cache logical partition (CLPR) to access the mapped volume. It is strongly

recommended that you place External Storage array groups in a CLPR other than CLPR0. See

the HP StorageWorks XP24000/XP20000 Disk/Cache Partition User Guide for detailed

information on CLPR.

Cross-subsystem Paths

A cross-subsystem path is a route from a local storage system port to an external storage system

port. To prepare for possible failures of the cable, the switch, or the channel processor, HP

recommends that you create redundant cross-subsystem paths. This redundancy allows you to

continue performing the I/O operations to the external volumes when you maintain the cable. You

can set up to eight paths.

18 About XP External Storage Operations

1 2 ... 13 14 15 16 17 18 19 20 21 22 23 ... 169 170

Kommentare zu diesen Handbüchern

Keine Kommentare

HP XP20000 Bedienungsanleitung Seite 18

Kommentare zu diesen Handbüchern

Verwandte Produkte und Handbücher für Software HP XP20000