HP XP P9500 Storage - Manual (Page 32)

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
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
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.
Selecting 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
Read (Total) Cache Hit (%) None Logical Device
Read (Sequential)
Read (Random)
Read (CFW)
Write (Total)
32 Working with graphs