FICON Express2 Channel Performance Version 1.0 - IBM

FICON Express2 Channel Performance Version 1.0
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The Generation (G) field tells you a combination of which generation FICON channel is
being used and the speed of the fibre channel link for this CHPID at the time the machine
was IPL’d. A “4” appears in the G field for CHPID 95 in Figure 22. This means that this
channel is a FICON Express2 channel with a link speed of 2 Gbps. If this channel was
connected to a 1 Gbps director, then there would be a “3” in the G field. A “2” indicates a
FICON Express channel with a link speed of 2 Gbps and a “1” indicates a FICON Express
channel operating at 1Gbps.
For a given FICON channel there are three possible entries under UTILIZATION (%):
1. PART denotes the FICON processor utilization due to this logical partition.
2. TOTAL denotes the FICON processor utilization for the sum of all the LPARs.
3. BUS denotes the FICON PCI bus utilization for the sum of all the LPARs.
The FICON processor is busy for channel program processing, which includes the processing
of each individual channel command word (CCW) in the channel program and some setup
activity at the beginning of the channel program and cleanup at the end. A very precise
algorithm is used for calculating zSeries FICON Express and FICON Express2 channel
utilizations. This algorithm is based on monitoring the amount of time the channel processor
spends doing various separate functions, and the results of this algorithm give a much more
accurate measure of FICON processor busy time than the original algorithm based on
counting command and data sequences, which is still used for 9672 G5/G6 FICON channels.
The FICON bus is busy for the actual transfer of command and data frames from the FICON
channel chip to the fibre channel adapter chip, which is connected via the fibre channel link
to the director or control unit. For FICON and FICON Express channels, the FICON bus is
also busy when the FICON processor is polling for work to do. This is why one can see
anywhere from 5 to 15% FICON bus utilization on the RMF Channel Activity report during
time intervals when there are no I/Os active on those channels. The new FICON Express2
channels, however, no longer use the bus for polling and therefore the bus utilization should
be less than 1% for these channels when there are no I/O’s active for an entire RMF
reporting interval.
The actual FC channel processor and bus utilizations as reported by RMF will vary by
workload and by channel type. As shown in Figure 22 above, FICON Express2 channels
provide bandwidth information (MB/SEC) not available for ESCON channels. This is
provided separately for READs and WRITEs since the fibre channel link is full duplex, at
both the logical partition level (PART) and the entire system level (TOTAL). Fibre channel
link utilizations are not directly reported on RMF but can be easily calculated by dividing the