HP StorageWorks XP12000 User Manual - Page 22

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Partial Cache Residence (PCR) operations

The XP10000/XP12000 has a special network board that allows the array to be connected directly to a

LAN. This network connection interface is called Network Attached Storage (NAS).

The NAS disk array uses a cache to store two types of data:

•

Management information (called i-node), including information on managing file system directories

and file pointers

•

Log information, used by the NAS channel file system to improve performance of data throughput in the

LAN via the NAS channel

This cache function is called Partial Cache Residence (PCR). A PCR cache is assigned to each channel,

and the PCR cache is shared and used by all files that are accessed through NAS channels. User data

transferred through a NAS channel uses the ordinary cache area.

(cache extent).

Figure 6

To perform PCR operations, you must belong to the Administrators or StorageAdmins group. If you belong

to the Users group, you can only view PCR information.

NOTE:

Only users belonging to the Administrators group are permitted to make modifications to arrays.

Click Cache LUN in the left pane. The Cache LUN pane appears.

Cache LUN XP for the XP10000/XP12000

Figure 6

shows the PCR cache area