CHAN - Channel Path Activity report

The Channel Path Activity report provides information about channel path use.

The report identifies each channel path by identifier and channel path type, and reports both the total channel utilization by the central processing complex (CPC) and the channel utilization of the individual system image (partition).

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 (---) are displayed instead of data. Please refer to the information APAR II05151 for a list of channel types for which channel utilization data is not gathered.

The report includes data for each valid online channel path. Data, however, does not appear for any channel path that was offline at the end of the interval or that was brought online during the interval. Instead, one of the following messages appears in the data field:

NOW ONLINE

Brought online during the interval and still online at the end of the interval

NOW OFFLINE

Taken offline during the interval and still offline at the end of the interval

OFFLINE

Offline for the entire interval

DELETED

Deleted during the interval

MODIFIED

Modified during the interval

INSTALLED

Installed during the interval

For all channels that are managed by dynamic channel path management (DCM), additional information is available. DCM allows an installation to identify channels that 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.

Duration report

Any channel that moved online or offline during the duration interval is indicated by an asterisk following the channel identifier.

In this report, the mode of the central processing complex (CPC) can be the following:

BASIC

The report shows all channels configured in the system. Only data for total utilization is reported. The partition utilization column is blank.

NOW BASIC

The report shows the last active mode. If you combine the SMF records from before and after a power-on-reset (POR) and changed the mode, two modes appear in the SMF records. By combining the intervals of the SMF records into one duration report, RMF displays the last active mode in the mode field. The partition utilization column is blank.

LPAR

The report shows the individual PR/SM logical partition's utilization and the total utilization of the shared ESCON channels, and the partition's and total utilization of the unshared channels.

NOW LPAR

The report shows the last active mode. If you combine the SMF records from before and after a POR and changed the mode, two modes appear in the SMF records. By combining the intervals of the SMF records into one duration report, RMF displays the last active mode in the mode field. The partition utilization column is blank.

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.