Asynchronous Event Detection (In Detail) - HP B6191-90029 User Manual

Asynchronous Event Detection (in Detail)

The following steps describe the process involved in asynchronous event detection. The asynchronous
detection is illustrated in Figure 3-3 on page 68.
1. A device driver detects an error during an I/O with the device.
2. The device driver passes the error information, including SCSI sense data, to the diag2 pseudo driver,
which adds information indicating the instance of the driver logging the error to the message header. The
error message is then passed to the diaglogd daemon used by STM to monitor recoverable errors.
3. Diaglogd uses the instance information to retrieve hardware path, product type, product name, and
driver name information from the message header. This information is used to determine which monitor,
if any, the information should be passed to. The error message is also written to the raw error log
(/var/stm/logs/os/log#.raw.cur).
During startup, each asynchronous monitor registered with diaglogd, indicating what types of errors the
monitor wants to receive. The monitor may specify a product description, product number, or driver name.
If a monitor is registered to receive the error, the message is passed to it.
4. The monitor decodes the error to determine if an event should be reported. If an event should be reported,
the monitor passes the event message to Event Monitoring Service (EMS).
5. EMS uses the current monitoring requests for the monitor to determine what action to take. Based on the
requests, the event is reported using the specified notification method(s).
Event Decoding
In addition to monitoring hardware, many of the EMS hardware monitors also act as message decoders for
logtool, which is used to read the contents of the raw error log. If the error uses an EMS hardware monitor
as the decoder, logtool launches a new instance of the monitor to perform the decoding. In this way all
events that have occurred on the device, including those IGNORED by the monitor, can be viewed.
Chapter 3
Detailed Description
The Detailed Picture of Hardware Monitoring
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