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

To request the Channel Path Activity report, select 3 from the Primary Menu and then select 12 on the Resource Report Selection Menu (shown in Figure 1), or enter the following command: 
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

Figure 1. CHANNEL Report
                      RMF V2R4  Channel Path Activity            Line 1 of 69
Command ===>                                                  Scroll ===> HALF

Samples: 60      System: CB88  Date: 05/11/19  Time: 08.00.00  Range: 60    Sec

 Channel Path       Utilization(%)   Read(B/s) Write(B/s)  FICON OPS  zHPF OPS
ID No  G  Type  S   Part  Tot  Bus   Part  Tot  Part  Tot  Rate Actv  Rate Actv

    4    *CNCSM      0.1  0.3
    4    *FC_SM      0.0  0.0  0.0      0    0     0    0     0    0     0    0
12        OSD   Y    0.0  0.0  0.0     2K  19K     0    0
14        OSD   Y    0.0  0.0  0.0     5K 531K  511K 514K
16        OSD   Y    0.4  1.3  0.0   511K   5M    3M   5M
20        CTC_S Y    0.0  0.0
27        CNC_S Y    0.0  0.0
2B        CNC_S Y    1.3  5.2
2C        CNC_S Y    0.2  0.5
30     5  FC_S  Y    0.0 32.5  8.9    205  52M   205 235K   186    1     0    0
31     5  FC_S  Y    0.0 33.3  8.5    429  50M   330 249K   185    2     0    0
37     4  FC_S  Y    0.0  0.5  0.1      0 619K     0  42K    24    1     0    0
38     4  FC_S  Y    0.0  0.5  0.1      0 613K     0  73K    30    2     0    0
39     4  FC_S  Y    0.0  0.1  0.0    374  23K     0  31K     8    1     0    0
3A     4  FC_S  Y    0.0  0.1  0.0    365  21K     0  32K     7    1     0    0
3E     4  FC_S  Y    0.0  0.0  0.0      0  10K     0   1K     3    1     0    0
7C        CNCSM Y    0.3  0.8
7D        CNCSM Y    0.1  0.1
81     3  FC_S  Y    1.1 14.2  3.2   801K  18M  147K   1M   738    2   132    1
82     5  FC_S  Y    0.1  0.4  0.2    37K 870K   28K  86K     7    1    36    1
83     5  FC_S  Y    0.0  0.4  0.2    36K 887K   27K  83K     8    1    36    1
84     4  FC_S  Y    0.0  0.0  0.0     25  101     0    0     0    1     0    0
85     3  FC_S  Y    0.4  6.8  0.7    62K   2M   61K   1M   420    1   157    1
8C     3  FC_S  Y    0.6 10.8  1.4   344K   6M   61K 801K   720    2     0    0
A6     5  FC_SM Y    0.0  0.0  0.0      0    0     0    0     0    0     0    0
B6     5  FC_SM Y    0.0  0.0  0.0      0    0     0    0     0    0     0    0
E0        IQD   Y                                  0 315K
E1        IQD   Y                                  0    0
E2        IQD   Y                                  0    0
E3        IQD   Y                                  0    0

The graphic form of the Channel Path Activity report shows the percentage of total utilization for each channel.

Field descriptions

Table 1. Fields in the CHANNEL Report
Field Heading Meaning
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 D M=CHP(xx) to see an explanation of the channel path type.

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:
  1. On a machine running in LPAR mode, but with only one LPAR defined, the Part columns for the Read, Write and Utilization fields display a zero value for channels of type FC (FICON).
  2. When Channel Path Measurement Facility (CPMF) is not available, for example, on z/OS systems running as z/VM guests, RMF uses sampled data from SRM so that the reported channel utilization is only an approximate value. With increasing channel speed, the channel utilization value becomes more and more inaccurate. Therefore, in such cases, RMF does not provide accurate values of FICON channel utilization.

    Beginning with z990 processors, the channel data from SRM is no longer available. As a result, the channel utilization data on a z/OS system running as z/VM guest, is reported as ' ------ '
Utilization (%) Part The channel path utilization percentage for an individual partition. RMF uses the values provided by CPMF. 
Part                Channel Path Busy Time
Utilization (%) = ------------------------- * 100
                  Channel Path Elapsed Time

For channels like FICON, OSA Express, or OSA Direct Express, which are running in extended CPMF mode, the calculation is as follows:

Part                          LPAR # of Channel Work Units
Utilization (%) = ------------------------------------------------------- * 100
                  Max # of Channel Work Units * Channel Path Elapsed Time

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:

                  # SRM Observations of
Total               Channel Path Busy
Utilization (%) = --------------------- * 100
                      # SRM samples

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:

Total                         Total # of Channel Work Units
Utilization (%) = ------------------------------------------------------- * 100
                  Max # of Channel Work Units * Channel Path Elapsed Time

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)
Part
Data transfer rates from the control unit to the channel for this partition.
Total
Data transfer rates from the control unit to the channel for the CPC.

For hipersockets, this value is not available.
Write(B/s)
Part
Data transfer rates from the channel to the control unit for this partition.
Total
Data transfer rates from the channel to the control unit for the CPC.
FICON OPS
Rate
Number of native FICON operations per second.
Actv
The average number of native FICON operations that are concurrently active during the report interval.
zHPF OPS
Rate
Number of zHPF (High Performance FICON) operations per second.
Actv
The average number of zHPF operations that are concurrently active during the report interval.

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:

Table 2. Additional Fields in the CHANNEL Report
Field Name Meaning
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.