MLCU
The service displays data (I/O rate, requests deferred for control unit, and device busy conditions) for logical control units that have I/O activity during the monitoring period.
Use this service to determine the optimal physical device placement and to evaluate shared DASD contention.
Syntax
The parameters are defined as follows:
Parameters | Description |
|---|---|
lcu | logical control unit |
lcu1-lcu2 | range of logical control units; lcu1 is the lowest-numbered logical control unit, and lcu2 is the highest-numbered logical control unit |
time | specifies the length of the sample period in seconds; the default sample period is 15 seconds, and the maximum period is 1,200 seconds |
Example
To monitor all LCUs for 15 seconds, type
MLCU
AMTO41I LOGICAL Control UNIT ACTIVITY REPORT
[1] [2]
AMTO63I IOP 01: ACTIVITY RATE 0000 AVG Q LENGTH 0000
[3] [4]
AMTO61I LCU 023: CONTENTION RATE 0005 ALL PATHS BUSY 0001
[5] [6] [7]
AMTO62I LCU 023: DELAY Q LENGTH 0000 CHPID TAKEN 0000 % CU BUSY 0000
Legend:
- total number of I/O requests per second received for all devices associated with the LCU
- average depth of the I/O request queue
- rate at which I/Os were queued on the LCU in the I/O subsystem
- percentage of time that all paths to a given I/O device on that LCU were busy
- average length of the queue for the LCU
- percentage of I/O requests processed by this LCU that were initiated successfully
- percentage of I/O requests processed by this LCU that were deferred because of a busy physical control unit
Usage note
The MLCU service uses a sampling technique for measuring I/O activity. The default sampling period is 15 seconds at a rate of four samples per second. If you enter an override value for time, the sample rate is four samples per second if the period is 15 seconds or less and two samples per second if the period is greater than 15 seconds.