Memcached

Dynatrace Memcached server monitoring provides insights into your distributed memory-object caching system so that you can pinpoint server performance issues and identify potential bottlenecks.

Prerequisites

  • Dynatrace OneAgent version 1.95+
  • Memcached Server 1.4.24+
  • Dynatrace supports TCP UDP and socket connections to Memcached servers. Admin permissions are required for socket connection types 666 or higher.

Enabling Memcached monitoring globally

With Memcached monitoring enabled globally, when a new host running Memcached is detected in your environment Dynatrace automatically collects Memcached metrics.

  1. In the navigation menu, select Settings.
  2. Select Monitoring > Monitored technologies.
  3. On the Supported technologies tab, find the Memcached entry and set the Global monitoring switch for Memcached to the On position.
    Memcached server monitoring is enabled globally.

Enabling Memcached monitoring for individual hosts

Dynatrace provides the option of enabling Memcached monitoring for specific hosts rather than globally.

  1. If global Memcached monitoring is currently switched on, switch it off: go to Settings > Monitoring > Monitored technologies and set the Memcached switch to the Off position.
  2. In the navigation menu, select Hosts.
  3. Find the host you want to configure.
    Use the filter at the top of the list to help you locate the host.
  4. Click the host to open the host page.
  5. In the host menu ("..."), select Edit to open the Host settings page.
  6. In the Monitored technologies list, find the Memcached row and set the Monitoring switch to the On position.
    Memcached monitoring is enabled for the selected host.

Memcached monitoring metrics

Key Memcached metrics are displayed on each Memcached process page within an intuitive infographic. Click the Memcached metrics and Further details tabs to view deeper insights.

Key metrics

Metric Description
Cache usage Percentage of available memory used for Memcached.
Connections Number of open connections.

Standard metrics

Metric Description
Evictions Number of valid items removed from cache to free up memory for new items. Evictions indicate that either:
  • Memcached has used all available memory (you can check the Cache usage metric to see the percentage of memory that’s utilized)
  • Memcached has available memory, but your slabs aren’t ideally allocated for the objects you’re storing.
Bytes Current number of bytes used to store items.
Max bytes Maximum number of bytes allowed in cache. You can adjust this setting via a config file or the command line while starting your Memcached server.
Current Number of open connections. There should always be available space for new connections. The default max setting for simultaneous connections is 1024.
Get Number of GET requests received by server per second.
Set Number of SET requests received by server per second.
Hits Number of successful GET requests (items requested and found) per second. The ratio of hits to misses should be as high as possible. Note that this ratio is low following Memcached restart (when the database receives data).
Misses Number of missed GET requests (items requested but not found) per second. These occur when nothing has been cached for a requested key or the cached value of an object is expired.
Read Number of bytes per second sent from the network and read by the server.
Written Number of bytes per second sent by the server to the network.