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The Process Manager
Each entry in the services table specifies which command to run, who can run it and
on which host.
4.6.1 Interaction with the Database
The Transaction Log Manager maintains the transactions table (see Section 10.2.23).
It consults the services table (see Section 10.2.20) in order to execute transactions on
behalf of its clients.
4.7 The Event Manager
When an RMS daemon detects an anomaly (such as a node crash or a high temperature
reading), it writes an event description to the events table (see Section 10.2.6). It is the
job of the Event Manager, eventmgr, to execute recovery scripts that either correct the
fault or report it to the operators if manual intervention is required.
On receiving an event notification, the Event Manager looks for a matching entry in the
event_handlers table (see Section 10.2.7), executing the handler script if it finds a
match (see Section 8.2 for details). If no match is found, it runs the default event
handler script; this script is site-specific, but it would typically run a command to
escalate the event through SNMP or email.
The Event Manager also implements the event-waiting mechanism that enables client
applications both to generate and to wait efficiently on a specified event. Typical events
include the following:
• Nodes changing state
• Partitions starting
• Transaction log entries being executed
The details that describe the event are held in the events table (see Section 10.2.6).
The Event Manager’s job is to notify interested clients that the event has occurred. This
frees the clients from having to poll for the information. For more information on RMS
event handling, see Chapter 8 (Event Handling).
4.7.1 Interaction with the Database
The Event Manager consults the events table (see Section 10.2.6) and the
event_handlers table (see Section 10.2.7).
4-6 RMS Daemons