HP XP RAID Manager Software - Manual (Page 35)

Usage rate of a data recovery and reconstruction processor
Function
A data recovery and reconstruction processor (DRR) is a microprocessor (located on the DKAs and
channel adapters) that is used to generate parity data for RAID 5 or RAID 6 parity groups. The
DRR uses the formula "old data + new data + old parity" to generate new parity.
If the monitor data shows high DRR usage overall, this can indicate high write penalty condition.
Please consult your HP representative about high write penalty conditions.
Storing period
Short-Range or Long-Range can be specified.
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 Usage Rate (%) DRR Controller
Usage rate of cache memory
Function
When you display monitoring results in a short range, the window displays the usage rates about
the cache memory for the specified period of time.
Storing period
Short-Range can be specified.
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 Usage Rate (%) None Cache
Write pending statistics
Function
The write pending rate indicates the ratio of write pending data to the cache memory capacity.
The Monitor Performance window displays the average and the maximum write pending rate for
the specified period of time.
Storing period
Short-Range or Long-Range can be specified.
Usage rate of a data recovery and reconstruction processor 35