HP XP RAID Manager Software - Manual (Page 40)

Selection of monitoring objects
Select monitoring objects in Performance Objects field. The combination of items is shown as
follows.
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 Response Time (ms) None Port*
None Response Time (ms) WWN WWN*
None Response Time (ms) Port
Total Response Time (ms) None Logical Device*
Read
Write
Total Response Time (ms) None Parity Group*
Read
Write
Total Response Time (ms) None LUN*
Read
Write
Total Response Time (ms) Parity Group External Storage*
Read
Write
Total Response Time (ms) Logical Device
Read
Write
* Volumes that do not accept I/O from the host, such as pool-VOLs, are not monitored.
Cache hit rates
Function
The cash hit rate is a rate that the input or output data of the disk exists in the cache. The cash 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
40 Working with graphs