Collecting data using DASD statistics

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The DASD statistics kernel function monitors the activities of the DASD device driver and the storage subsystem. It mainly records processing time of I/O operations within a given time interval.

Procedure

To collect diagnostic data by using DASD statistics:

Start DASD statistics with the following command:
```
# echo set on > /proc/dasd/statistics
```
Summarized histogram information is available in /proc/dasd/statistics, and can be extracted with the following command:
```
# cat /proc/dasd/statistics
```
Stop DASD statistics with the following command:
```
# echo set off > /proc/dasd/statistics
```

Results

DASD statistics creates a summary for all devices.

An IOCTL interface is available to collect the statistics for individual devices. To get DASD statistics for an individual DASD, first turn statistics collection on, then use the tunedasd command:

# echo set on > /proc/dasd/statistics
# tunedasd -P /dev/dasd<xx>

What to do next

After you collect the appropriate diagnostic data, you can complete the following tasks: