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130 Storage Management with DB2 for OS/390
• AVG CONN TIME, connect time mainly for data transfer. To estimate path
percentage utilization demand, calculate:
AVG CONN TIME * DEVICE ACTIVITY RATE/1000)*100
• As an example, an average connect of 4.5 ms with 1200 I/O/sec gives 540%,
which means a minimum of six paths is required for this workload level.
Checking the channel path activity reports for the different LPARS sharing this
LCU enables you to determine the balance of the activity demand (540%) over
the current defined path configuration. Intermediate consolidations may be
required in complex configurations.
• % DEV UTIL, percentage of device utilization shows the percentage of times
RMF has found this device busy. This is a good indicator of demand
contention on this volume.
I/O Queuing Activity Report
The I/O Queuing Activity report (see Figure 51 on page 131) is used to analyze
the pathing behavior. To get this report, specify:
REPORTS (IOQ)
Use only two fields, LCU and CHAN PATHS, which list the physical paths to
review later in the channel path activity report.
Channel Path Activity Report
The Channel Path Activity report ( Figure 52 on page 132) identifies performance
contentions associated with the channel paths. To produce this report, specify:
REPORTS (CHAN)
Review the following fields:
• CHANNEL ID is the hexadecimal number of the channel path identifier
(CHPID).
• PATH SHR; a value of Y indicates that the ESCON channel link (physical
channel) is shared between one or more LPARs.
• PARTITION UTILIZATION (%) is the percentage of physical channel path
utilization by the LPAR.
• TOTAL UTILIZATION (%) is the percentage of physical channel path utilization
that all LPARS of this CPC use. This is the aggregate view of channel
utilization.