Memcached

Monitor cache performance, hit ratios, memory utilization, and network throughput for your local Memcached instance. The agent connects to the Memcached service and runs the stats command to collect real-time operational data, helping you optimize cache efficiency and resource allocation.

Setup

Preparing Memcached for monitoring typically requires no additional configuration if it is bound to the local interface, as the agent probes the default port 11211.

1. Verify bind address: Ensure Memcached is listening on 127.0.0.1. Check your /etc/memcached.conf for the -l 127.0.0.1 directive.
2. Restart Memcached: If you modified the configuration, restart the service: sudo systemctl restart memcached.
3. Restart the agent: Restart simob to trigger service discovery for the new endpoint: sudo systemctl restart simob.
4. Enable in UI: Once discovered, explicitly enable the Memcached collector in your dashboard’s server configuration panel.

Configuration

The agent automatically discovers Memcached if it is running on the default port 11211 on localhost. No additional configuration is required for standard installations.

Metrics

The following metrics are collected from the Memcached stats output:

Metric	Type	Unit	Description
memcached_connections_current_total	Gauge	-	Number of open connections to the server.
memcached_connections_rate	Gauge	conns/s	Rate of new connections per second.
memcached_items_current_total	Gauge	-	Total number of items currently stored by the server.
memcached_items_rate	Gauge	items/s	Rate of new items being stored in the cache.
memcached_get_rate	Gauge	ops/s	Number of get commands processed per second.
memcached_set_rate	Gauge	ops/s	Number of set commands processed per second.
memcached_get_hits_rate	Gauge	hits/s	Number of keys that have been requested and found per second.
memcached_get_misses_rate	Gauge	misses/s	Number of keys that have been requested and not found per second.
memcached_delete_hits_rate	Gauge	ops/s	Number of deletion requests that successfully found a key.
memcached_delete_misses_rate	Gauge	ops/s	Number of deletion requests for keys that did not exist.
memcached_incr_hits_rate	Gauge	ops/s	Number of increment requests that successfully found a key.
memcached_incr_misses_rate	Gauge	ops/s	Number of increment requests for keys that did not exist.
memcached_decr_hits_rate	Gauge	ops/s	Number of decrement requests that successfully found a key.
memcached_decr_misses_rate	Gauge	ops/s	Number of decrement requests for keys that did not exist.
memcached_read_bps	Gauge	bytes/s	Total bytes read by the server from the network per second.
memcached_written_bps	Gauge	bytes/s	Total bytes written by the server to the network per second.
memcached_limit_bytes	Gauge	bytes	Maximum number of bytes the server is allowed to use for items.
memcached_used_bytes	Gauge	bytes	Current number of bytes used by the server to store items.

Troubleshooting

Verify the endpoint

You can manually verify that Memcached is responding to the stats command using nc (netcat):

echo "stats" | nc 127.0.0.1 11211

Or using memstat if the libmemcached-tools package is installed:

memstat --servers=127.0.0.1

Discovery issues

If Memcached is not appearing in the UI, ensure that it is running and accessible on 127.0.0.1:11211. If you are using a custom port or address, please note that current auto-discovery only supports default settings.