check_memcached will give a critical message if a partiular memcached host is inaccessible.

It will generate a warning (only) if the hit/miss ratio falls below a given threshold (default 2) It will generate a warning (only) if the number of evictions exceeds a given limit (default 10)

Hit/miss and evictions are measured over a 30 minute interval, using a memcached object to store the earlier statistics. Almost ALL other check_memcached plugins just quote the raw stats, which are measured from when the daemon was last started. By distinction, this plugin measures the hit/miss ratio over a well-defined time-interval (by default the last 30 minutes)

The thresholds for the hit/miss ratio and eviction-rate may be specified on the command line. The measurement time-interval may also be specified on the command line (this interval is also used for the performance data)

Set $memcached_graph_composite = 0 to plot 4 graphs:

  • 1st graph: gets and hits
  • 2nd graph: sets and misses
  • 3rd graph: hit/miss ratio
  • 4th graph: evictions

Set $memcached_graph_composite = 1 to plot 2 graphs:

  • 1st graph: has gets and hits in the positive direction, and sets, misses and evictions in the negative direction
  • 2nd graph: is hit/miss ratio on it's own

This plugin is written in C and also requires:  Flex:  libmemcached:

  • v1.3 added rate-based performance statistics for better pnp4nagios integration (-r option)