# os_mon

### APPLICATION

os_mon

### APPLICATION SUMMARY

OS Monitoring Application

### DESCRIPTION

The operating system monitor, OS_Mon, provides the following services:

- cpu_sup CPU load and utilization supervision (Unix)
- disksup Disk supervision(Unix, Windows)
- memsup Memory supervision (Unix, Windows, VxWorks)
- os_sup Interface to OS system messages (Solaris, Windows)

To simplify usage of OS_Mon on distributed Erlang systems, it is not considered an error trying to use a service at a node where it is not available (either because OS_Mon is not running, or because the service is not available for that OS, or because the service is not started). Instead, a warning message is issued via `error_logger` and a dummy value is returned, which one is specified in the man pages for the respective services.

### Configuration

When OS_Mon is started, by default all services available for the OS, except `os_sup`, are automatically started. This configuration can be changed using the following application configuration parameters:

`start_cpu_sup = bool()`
  Specifies if `cpu_sup` should be started. Defaults to `true`.
`start_disksup = bool()`
  Specifies if `disksup` should be started. Defaults to `true`.
`start_memsup = bool()`
  Specifies if `memsup` should be started. Defaults to `true`.
`start_os_sup = bool()`
  Specifies if `os_sup` should be started. Defaults to `false`.

Configuration parameters effecting the different OS_Mon services are described in the respective man pages.

See config(4) for information about how to change the value of configuration parameters.

### SNMP MIBs

The following MIBs are defined in OS_Mon:

OTP-OS-MON-MIB
  This MIB contains objects for instrumentation of disk, memory and CPU usage of the nodes in the system.

The MIB is stored in the `mibs` directory. It is defined in SNMPv2 SMI syntax. An SNMPv1 version of the MIB is delivered in the `mibs/v1` directory.

The compiled MIB is located under `priv/mibs`, and the generated `.hrl` file under the `include` directory. To compile a MIB that IMPORTS the `OTP-OS-MON-MIB`, give the option `{il, ["os_mon/priv/mibs"]}` to the MIB compiler.

If the MIB should be used in a system, it should be loaded into an agent with a call to `os_mon_mib:load(Agent)`, where `Agent` is the pid or registered name of an SNMP agent. Use `os_mon_mib:unload(Agent)` to unload the MIB. The implementation of this MIB uses Mnesia to store a cache with data needed, which implicates that Mnesia must be up and running. The MIB also use functions defined for the `OTP-MIB`, thus that MIB must be loaded as well.

### See Also

cpu_sup(3), disksup(3), memsup(3), os_sup(3), nteventlog(3), snmp(3).

### AUTHORS

Martin Björklund - support@erlang.ericsson.se
Mats Nilsson - support@erlang.ericsson.se

os_mon 2.1
Copyright © 1991-2006 Ericsson AB