Hitachi MK-96RD617-08 - Manual (Page 26)

2-10 About Performance Manager Options
Hitachi Universal Storage Platform V/VM Hitachi Performance Manager User’s Guide
Access Path Usage Statistics
An access path is a path through which data and commands are transferred
within a storage system.
In a storage system, channel adapters control data transfer between hosts and
the cache memory. Disk adapters control data transfer between the cache
memory and hard disk drives. Data transfer does not occur between channel
adapters and disk adapters. Data is transferred via the cache switch (CSW) to
the cache memory.
When hosts issue commands, the commands are transferred via channel
adapters to the shared memory (SM). The content of the shared memory is
checked by disk adapters.
DKA DKA DKA DKA
CHA CHA CHA CHA
cache switch （CSW）
cache
memory
CHA: channel adapter
DKA: disk adapter
shared
memory
Figure 2-1 Access Paths
Performance Monitor tracks and displays the usage rate for the following
access paths.
• Paths between channel adapters and the cache switch
• Paths between disk adapters and the cache switch
• Paths between the cache switch and the cache memory
• Paths between channel adapters and the shared memory
• Paths between disk adapters and the shared memory
For details on how to view usage statistics about access paths, see Viewing
Usage Statistics on Access Paths.