HP XP7 Storage - Manual (Page 37)

Selection of monitoring objects
Select the desired monitoring objects in the Performance Objects field.
Item on right side of Monitor
Data field Item on left side of Monitor Data
field Item on right side of
Object field Item on left side of Object
field
None HTP Port Open Exchanges
(count/sec) None Mainframe Fibre Port*
* Volumes that do not accept I/O from the host, such as pool-VOLs, are not monitored.
Cache hit rates
Function
The cache hit rate is a rate that the input or output data of the disk exists in the cache. The cache
hit rate is displayed for the sequential access mode, the random access mode, the cache fast write
(CFW) mode, and the entire these modes.
•
Read hit ratio
For a read I/O, when the requested data is already in cache, the operation is classified as
a read hit. For example, if ten read requests have been made from hosts to devices in a given
time period and the read data was already on the cache memory three times out of ten, the
read hit ratio for that time period is 30 percent. A higher read hit ratio implies higher processing
speed because fewer data transfers are made between devices and the cache memory.
•
Write hit ratio
For a write I/O, when the requested data is already in cache, the operation is classified as
a write hit. For example, if ten write requests were made from hosts to devices in a given time
period and the write data was already on the cache memory three cases out of ten, the write
hit ratio for that time period is 30 percent. A higher write hit ratio implies higher processing
speed because fewer data transfers are made between devices and the cache memory.
Storing period
Short-Range can be specified.
Selection of monitoring objects
Select the desired monitoring objects in the Performance Objects field.
Item on right side of Monitor
Data field Item on left side of Monitor
Data field Item on right side of Objecc
field Item on left side of Object
field
Read (Total) Cache Hit (%) Base Logical Device*
Read (Sequential)
Read (Random)
Read (CFW)
Write (Total)
Write (Sequential)
Write (Random)
Write (CFW)
Cache Hit (%) Initial Copy Cnt Ac-J/Cnt Ac-J Z
Cache hit rates 37