OVNM 5.3 - Operations Agent for NonStop Event Management Guide for UNIX

HP NonStop Event Management System 22
Log File Management
The collector writes messages to the log files. The collector writes messages one at a time or writes a number of
messages to a buffer then writes that entire message group to the log file. The process of writing a group of
messages to a buffer is known as blocking. Blocking significantly increases the speed at which messages are
written to the log file.
Tasks associated with log switches (switching to using a new log file when the current file becomes full) are
performed when the collector is idle; that is, when there are no events to log. The tasks include purging and
deallocating (disk space) the old log file and preallocating (disk space for) the next log file.
Each collector maintains its log files according to parameters you specify. These parameters can vary for each
collector, and they control the following log file variables:
• Disk volume and subvolume in which the log files are to be created
• Number of log files that can exist concurrently in one subvolume
• Primary-extent and secondary-extent sizes for each file
• Whether or not event messages are blocked before they are written to the log file
• Whether or not the file label is updated on disk each time the end of file is advanced
• Security attributes of the log files the collector creates
Primary Collector Log-File Attributes
The primary collector assumes default values for log file parameters at system generation. You can change the
values programmatically through the collector's SPI ALTER or CONTROL commands or interactively through the
EMSCCTRL utility.
Alternate Collector Log-File Attributes
You can assign values to the parameters that control alternate collector log files when you issue the RUN
command to start the collector. If you do not specify a value for a log-file parameter, EMS uses a default value.
You can change the values of some attributes programmatically by using the SPI CONTROL command or
interactively through the EMSCCTRL program.
Distributor Support
In addition to logging event messages for retrieval by distributors, both the primary and alternate collectors
support the forwarding, consumer, and printing distributors by:
• Notifying distributors when new event messages are logged
• Accepting event messages forwarded from another node by a forwarding distributor
2-2-5 EMS Message Distributors
Event-message distributors have three basic functions:
• Accessing one or more log files
• Filtering event messages
• Routing the selected event messages to the appropriate destination
Depending on the nature of the destination, you can use one of four types of distributors:
Table 2-1 Distributor Types
Distributor Description
Consumer: Sends selected event messages to a requesting management application.
Forwarding: Sends selected event messages to an EMS collector on another node in the network or to an alternate
collector on the same node.
Printing: Obtains formatted text for selected event messages and writes it to a printer or other display device, or
to a file. When a routing filter is used, unformatted events can be routed to selected distributor
processes.
Compatibility: Filters event messages according to a fixed (rather than a user-specified) criterion, obtains formatted
text for the selected primary collector event messages, and writes it to a console device.