CHANNEL - Channel Path Activity Report
The Channel Path Activity report (CHANNEL) gives you information about channel path activity for all channel paths in the system. The report contains data for every channel path that is online during data gathering.
For all channels that are managed by Dynamic Channel Path Management (DCM), additional information is available. DCM allows an installation to identify channels which they wish to be managed dynamically. These channels are not assigned permanently to a specific control unit, but belong to a pool of channels. Based on workload requirements in the system, these channels will be assigned dynamically by DCM. On top of the report, there is a consolidated data section for managed channels displaying the total number of channel paths for each type and the average activity data. The character M as suffix of the acronym for the channel path type is an indicator that the channel is managed by DCM.
You can use channel path activity information together with I/O device activity and I/O queuing activity information to identify performance bottlenecks associated with channel paths.
To find out which logical control unit is using the channel, look in the I/O Queuing Activity report. From there you can go to check device response times. For example, if a channel path to a device shows excessive use, you could define additional paths to the device or introduce a different job mix to produce better performance.
How to request this report
CHANNEL
Special considerations of report output
You can obtain the report whether or not a Monitor I session measuring channel path activity is active.
Data for total utilization and partition utilization is gathered independently. Because the internal interval used to gather this data is a few seconds, the total utilization and the sum of the partition's utilization sharing that channel might differ if a short RMF interval is specified. If the interval is too small or the appropriate data cannot be gathered, dashes (---) will be reported instead of data. Please refer to the information APAR II05151 for a list of channel types for which channel utilization data is not gathered.
Contents of the report
The graphic form of the Channel Path Activity report shows the percentage of total utilization for each channel.
Field descriptions
Field Heading | Meaning |
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Channel Path ID | Hexadecimal channel path identifier (CHPID). |
Channel Path No | For each channel type which is managed by DCM, a summary line is shown with the average values for all channels in this group. These summary lines are characterized by an '*' preceding the channel path type, and the number of channels of the group is displayed in column No. |
Channel Path G | Generation.
The generation is used to differentiate between channels of the same channel type, when one has significant differences from the other. Newer generations with significant differences (for example, the channel throughput) are indicated by a number (1, 2, ...). For example, for a FICON channel, a number 1 indicates that the channel has an auto-negotiated throughput of 1GBit/sec, or a number 4 indicates a throughput of 2GBit/sec on a FICON Express4 card or a FICON Express2 card. |
Channel Path Type | Type of channel path.
You may issue the console command If RMF encounters an error while processing the type, this field is blank. RMF continues to measure channel path activity. Check the operator console for messages. |
Channel Path S | The indication of whether a channel path is defined as shared between one or more logical partitions. Y indicates that the channel path is shared. A blank indicates it is not shared. |
Note:
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Utilization (%) Part | The channel path utilization percentage for an individual partition.
RMF uses the values provided by CPMF.
For channels like FICON, OSA Express, or OSA Direct Express, which are running in extended CPMF mode, the calculation is as follows:
For some channels like OSAEGbE, FICON EXPRESS/EXPRESS2, this value reflects the microprocessor utilization. For hipersockets, this value is not available. |
Utilization (%) Tot | The channel path utilization percentage for the CPC during
an interval.
For processors earlier than z990 and shared channels in LPAR mode, where CPMF is not available, the calculation is:
For unshared channels in LPAR mode, the value for total utilization is the same as partition utilization. For channels like for example FICON, OSA Express, or OSA Direct Express, which are running in extended CPMF mode, the calculation is as follows:
For some channels like OSAEGbE, FICON EXPRESS/EXPRESS2, this value reflects the microprocessor utilization. For hipersockets, this value is not available. |
Utilization (%) Bus | Percentage of bus cycles, the bus has been found busy for this
channel in relation to the theoretical limit.
For OSAEGbE, the value reflects the PCI bus utilization. For hipersockets, this value is not available. |
Read(B/s) |
For hipersockets, this value is not available. |
Write(B/s) |
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FICON OPS |
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zHPF OPS |
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Monitor III Utility fields
You can use the Monitor III Utility to customize the CHANNEL report in a way that the following additional values are shown:
Field Name | Meaning |
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CHACFDFR | Number of deferred native FICON operations per second that could not be initiated by the channel due to a lack of available resources. |
CHACXDFR | Number of deferred zHPF operations per second that could not be initiated by the channel due to lack of available resources. |
CHACNET1 | Physical-network identifier (PNET ID) of first channel path port. |
CHACNET2 | Physical-network identifier (PNET ID) of second channel path port. |
The following fields are only available for HiperSockets: | |
CHACTMVC | Total message sent rate |
CHACTSVC | Total message sent size |
CHACTFVC | Total receive fail rate |
CHACPMVC | Rate of messages sent by this LPAR |
CHACPSVC | Average size of messages sent by this LPAR |
CHACPFVC | Rate of messages received by this partition that failed due to an unavailable buffer. The value could indicate that more receive buffers are required. |
CHACSFVC | Rate of messages sent by this partition that failed. |