This is a nagios plugin to monitor LSI MegaRAID and attached disks. Newer cards are called MTPFusion and many of these cards are sold by Dell under their own brand name "PERC" (PERC3 - PERC6). Older ones are SCSI RAID cards and newer are SAS RAID cards.

For Megaraid SCSI card you need to have percsnmp package installed. For SAS Megaraid card you need to have sassnmp package (download it from lsi.com, url is listed in the the plugin header doc part).

The plugin started as enhancements of the megaraid nagios plugin from http://www.ibiblio.org/john/megaraid/. Since then over 70% of the code has now been rewritten but it still has overall compatibility to original plugin. New additions include reporting of errors by looking up readfail & writefail OIDs (only on SCSI megaraid) and at 'medium' and 'other' disk errors and reporting if those number have changed (i.e. new error occured - on dell servers this is also reported by openmanage in syslog).

As part of its standard output line plugin also reports number of drives, logical disks and controllers (more fun then just seeing 'OK'), performance data is also provided for number of disk errors. For SCSI Megaraid, drive numbers are reported in format including including controller (0 represents controller 1), channel id (note that 0 is channel A and 1 is channel B) and scsi id.