Memcached monitoring

Deprecation notice

This extension documentation is now deprecated and will no longer be updated. We recommend using the new Memcached extension for improved functionality and support.

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. Go to Settings.
  2. Select Monitoring > Monitored technologies.
  3. On the Supported technologies tab, find the Memcached entry and turn on the Global monitoring switch for Memcached.
    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, select Monitoring > Monitored technologies, and turn off the Memcached switch.
  2. Go to Hosts or Hosts Classic (latest Dynatrace).
  3. Find the host you want to configure.
    Use the filter at the top of the list to help you locate the host.
  4. Select the host to open the host page.
  5. Select More (…) > Settings to open the Host settings page.
  6. In the Monitored technologies list, find the Memcached row and turn on the Monitoring switch.
    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.

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