swRaidMIB

    Net-SNMP-Plugin for monitoring
    Linux RAID devices

    (c) Copyright G. Kuhlmann, 2007

    This is free software. See COPYING for license.

INTRODUCTION:

This software is a loadable plugin module for the Net-SNMP agent to monitor the software RAID functions of a Linux system. It works by reading the file /proc/mdstat and providing the information read under the ucdExperimental OID with sub-ID 18. This sub-ID hasn't been regis- tered with anyone yet, but it was free at the time this software was written. The plugin module provides the following read-only variable tree:

+--swRaidMIB(18) | +--swRaidTable(1) | | | +--swRaidEntry(1) | | Index: swRaidIndex | | | +-- -R-- Integer32 swRaidIndex(1) | | Range: 0..65535 | +-- -R-- String swRaidDevice(2) | | Textual Convention: DisplayString | | Size: 0..255 | +-- -R-- String swRaidPersonality(3) | | Textual Convention: DisplayString | | Size: 0..255 | +-- -R-- String swRaidUnits(4) | | Textual Convention: DisplayString | | Size: 0..255 | +-- -R-- Integer32 swRaidUnitCount(5) | +-- -R-- EnumVal swRaidStatus(6) | Textual Convention: RaidStatusTC | Values: inactive(1), active(2), faulty(3) | +-- -R-- Integer32 swRaidErrorFlag(100) +-- -R-- String swRaidErrMessage(101) Textual Convention: DisplayString Size: 0..255

swRaidTable - Contains Information about every RAID device in the system. It consists of the following elements: swRaidIndex - Internal index number for each device swRaidDevice - Device name (for example "/dev/md1") swRaidPersonality - RAID personality of this device (for example "Raid1") swRaidUnits - Units within this RAID device encoded as a blank-seperated string (for exam- ple "/dev/sda1 /dev/sdb1") swRaidUnitCount - Number of units in the RAID device swRaidStatus - Status of the RAID device. This can be one of: inactive, active, faulty

swRaidErrorFlag - Contains a non-zero value if any of the RAID devices on the system is faulty

swRaidErrMessage - Contains the names of all faulty RAID devices in case the swRaidErrorFlag is non-zero

The swRaidErrorFlag and swRaidErrMessage variables are primarily provided to get a quick overview of the RAID system, for example by the use of an auto- mated monitoring script. They can also be used to generate SNMP trap or inform messages in case one or more of the RAID devices failed.

REQUIREMENTS:

To use this plugin module you obviously need a somewhat current Net-SNMP agent. It has been tested with Net-SNMP version 5.4. I don't know if it works with any older version. The agent has to be compiled with support for loadable modules (which is the default). In addition the Net-SNMP runtime libraries and include files have to be installed in order to compile the module.

INSTALLATION:

The swRaidMIB plugin module is not a huge software project, so no configure script has been written. Since this module only makes sense on a Linux system, and gcc is usually installed on such a system, the Makefile has been written to only support the GNU development tools. To compile on other Unix-like systems you would probably need to modify the Makefile. Therefore, to install this module, first run "make" in the source directory. Then copy the resulting file swRaidPlugin.so to a place where the SNMP agent can find it, for example /usr/lib/snmp/dlmod. Also copy the MIB file named SWRAID-MIB.txt to the place where all your other MIB files are stored, usually something like /usr/local/share/netsnmp/mibs or /usr/share/snmp/mibs.

In order for the SNMP agent to find the module you need a line in the snmpd configuration file telling it to load the module:

dlmod swRaidMIB /usr/lib/snmp/dlmod/swRaidPlugin.so

Now modify the snmpd startup script (depending on your distribution) to start the agent with the additional command line option

-m+SWRAID-MIB

which causes the agent to load the SWRAID-MIB in addition to all the other internal MIBs, and restart snmpd. You can now view the RAID data using your preferred SNMP client program, like mbrowse or snmpwalk. Depending on your security policies you can try the following command:

snmpwalk -v1 -c public -m+SWRAID-MIB localhost swRaidMIB

This should show you the same information you can get from the /proc/mdstat file. The plugin module will re-read /proc/mdstat at most once every 60 seconds. If you want to test the module, set one of the RAID drives to a faulty state (for example using the mdadm program) and wait a minute until you can see the result through SNMP.

SUPPORT:

If you need any help using this module, or you find a bug please let me know. Also, if you can think of any improvement or even have implemented any improvement yourself please send me an E-Mail to:

[email protected]

Please note that I wrote this program in my spare time, so answers may sometimes take a bit longer. I will not offer any commercial support for this program.