HP XP7 Storage - Manual (Page 29)

Usage rate of DRRs
Function
A data recovery and reconstruction processor (DRR) is a microprocessor (located on the DKAs and
CHAs) 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 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 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 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 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 DRRs 29