Channel measurement facility
The IBM Z® architecture provides a channel measurement facility to collect statistical data about I/O on the channel subsystem.
Data collection can be enabled for all CCW devices. User space applications can access this data through the sysfs.
The channel measurement facility provides the following features:
- Basic channel measurement format for concurrently collecting data on up to 4096 devices. (Specifying 4096 or more channels causes high memory consumption, and enabling data collection might not succeed.)
- Extended channel measurement format for concurrently collecting data on an unlimited number of devices.
- Data collection for all channel-attached devices, except those using QDIO (that is, except qeth and SCSI-over-Fibre channel attached devices)