DataStax OpsCenter Documentation

Configuring data collection and expiration

OpsCenter collects system and column family metrics data for each node in your cluster. OpsCenter creates its own keyspace within a cluster for storing collected metrics. Metrics data is collected at regular intervals and stored within your cluster in a keyspace called OpsCenter. The column families containing metric data continue to grow. You can configure how long you want to keep historical metrics. Data expires after configurable time periods.

Estimating the amount of data generated

The following table provides guidance for estimating the amount of metrics data generated:

Number of days Number of column families monitored MB per node
31 5 200
31 10 300
31 20 500
365 5 250
365 10 380
365 20 630

The default upper limit of data collected is 365 days.

Controlling data collection

To help control consumption of disk space, OpsCenter provides two ways to limit the growth of OpsCenter performance data:

  • By excluding specified keyspaces and column families from performance data collection
  • By shortening the time period after which performance data automatically expires

Excluding keyspaces and column families

By default, OpsCenter does not collect performance data for its own keyspace or the Cassandra system keyspace. You can manually add any other keyspaces or column families that you do not want to monitor in the [cassandra_metrics] section of the configuration file.

For example, to prevent data collection for the keyspace test as well as the column family Keyspace1.Standard1, uncomment and edit the following values in the OpsCenter cluster configuration file (<cluster_specific>.conf):

[cassandra_metrics]
ignored_keyspaces = system, OpsCenter, test
ignored_column_families = Keyspace1.Standard1

Column families are specified in the format:

<keyspace_name>.<column_family_name>.

Changing performance data expiration times

Performance data stored in OpsCenter expires after configurable time periods. The default values are designed to provide efficient compaction and eventual deletion of the data, with faster expiration times for the more granular, larger-volume data rollups.

  • One-minute rollups (1min_ttl) expire after after one week, or 604800 seconds.
  • Five-minute rollups (5min_ttl) expire after four weeks, or 2419200 seconds.
  • Two-hour rollups (2hr_ttl) expire after one year, or 31536000 seconds.

To change expiration time period:

In this example, the one-minute and five-minute rollups are set to expire twice as fast as the defaults, and two-hour rollups are set to be kept indefinitely (expiration is disabled).

  1. Edit the conf/clusters/<cluster>.conf file.

  2. Add the following time-to-live (ttl) values under a [cassandra_metrics] section:

    1min_ttl = 302400
    5min_ttl = 1209600
    2hr_ttl = -1
    
  3. Restart OpsCenter.

    Data collected after restarting OpsCenter expires according to the new setting. The data collected before restarting OpsCenter expires according to the setting in effect when it was collected.