Partial Cache Residence (Pcr) Operations; Overview Of The Pcr Function; Pcr Operations; Pcr Cache Area (Cache Extent) - HP StorageWorks XP10000 User Manual

Partial Cache Residence (PCR) operations

Overview of the PCR function

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

PCR cache area (cache extent)

PCR operations

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.
1. Click Cache LUN in the left pane. The Cache LUN pane appears.
22 Cache LUN XP for the XP10000/XP12000
Figure 6 shows the PCR cache area