Data retention

Configure the data retention parameters

This page describes StackState version 4.2.

The StackState 4.2 version range is End of Life (EOL) and no longer supported. We encourage customers still running the 4.2 version range to upgrade to a more recent release.

Go to the documentation for the latest StackState release.

Overview

StackState imposes data retention limits to save storage space and improve performance. You can configure the data retention period to provide a balance between the amount of data stored, StackState performance, and data availability.

Retention of topology graph data

By default topology graph data will be retained for 8 days. This works in a way that the latest state of topology graph will always be retained; only history older than 8 days will be removed. You can check and alter the configured retention period this using the StackState CLI.

# Check the current retention period
sts graph retention get-window

In some cases, it may be useful to keep historical data for more than eight days.

# Set the configured retention period to 10 days
sts graph retention set-window --window 864000000

(note that time value is provided in milliseconds - 10 days equals 864000000 milliseconds)

Please note that by adding more time to the data retention period, the amount of data stored is also going to grow and need more storage space. This may also affect the performance of the Views.

After the new retention window is applied, you can schedule a new removal with this command:

# Schedule a new removal
sts graph retention set-window --schedule-removal

After changing the retention period to a smaller window, you may end up with some data that is already expired and will wait there until the next scheduled cleanup. To schedule an additional removal of expired data, use the following command:

Please note that this may take some time to have an effect.

# Schedule removal of expired data
sts graph retention remove-expired-data

However, if you would like to perform data deletion without having to wait for an additional scheduled cleanup, you can use --immediately argument:

# Remove expired data immediately
sts graph retention remove-expired-data --immediately

Retention of events, metrics and traces

StackState data store

If you are using the event/metrics/traces store provided with StackState, your data will by default be retained for 30 days. In most cases, the default settings will be sufficient to store all indices for this amount of time.

Configure disk space for Elasticsearch

In some circumstances it may be necessary to adjust the disk space available to Elasticsearch and how it is allocated to each index group, for example if you anticipate a lot of data to arrive for a specific index.

Kubernetes

The settings can be adjusted by using environment variables to override the default configuration of the parameters described below.

Note that elasticsearchDiskSpaceMB will scale automatically based on the disk space available to Elasticsearch in Kubernetes.

Linux

The settings can be adjusted in the file /opt/stackstate/etc/kafka-to-es/application.conf using the parameters described below.

Parameter	Default	Description
elasticsearchDiskSpaceMB	400000	The total disk space assigned to Elasticsearch in MB. The default setting is the recommended disk space for a StackState production setup (400GB).
splittingStrategy	"days"	The frequency of creating new indices. Can be one of "none", "hours", "days", "months" or "years". If "none" is specified, only one index will be used.
maxIndicesRetained	30	The number of indices that will be retained in each index group. Together with the splittingStrategy governs how long historical data will be kept in Elasticsearch.
diskSpaceWeight	Varies per index group	Defines the share of disk space an index will get based on the total elasticsearchDiskSpaceMB. If set to 0 then no disk space will be allocated to the index. See the disk space weight examples below.
replicas	Linux: 0 Kubernetes: 1	The number of nodes that a single piece of data should be available on. Use for redundancy/high availability when more than one Elasticsearch node is available.

Example application.conf

stackstate {
  ...

  // Total size of disk assigned to Elasticsearch in MB
  elasticsearchDiskSpaceMB = 400000

  ...

  // For each index group:
  // kafkaMetricsToES - the sts_metrics index
  // kafkaMultiMetricsToES - the sts_multi_metrics index
  // kafkaGenericEventsToES - the sts_generic_events index
  // kafkaTopologyEventsToES - the sts_topology_events index
  // kafkaStateEventsToES - the sts_state_events index
  // kafkaStsEventsToES - the sts_events index
  // kafkaTraceToES - the sts_trace_events index

  kafkaMultiMetricsToES {
    ...
    elasticsearch {
      index {
        splittingStrategy = "days"
        maxIndicesRetained = 30
        refreshInterval = 1s
        replicas = 0 // Default setup is single node
        diskSpaceWeight = 1
      }
    ...
    }
  }
  ...
}

Disk space weight examples

Use the diskSpaceWeight configuration parameter to adjust how available disk space is allocated across Elasticsearch index groups. This is helpful if, for example, you expect a lot of data to arrive in a single index. Below are some examples of disk space weight configuration.

Allocate no disk space to an index group Setting diskSpaceWeight to 0 will result in no disk space being allocated to an index group. For example, if you are not going to use traces, then you can stop reserving disk space for this index group and make it available to other index groups by setting kafkaTraceToES.elasticsearch.index.diskSpaceWeight = 0.

Distribute disk space unevenly across index groupsThe available disk space (the configured elasticsearchDiskSpaceMB) will be allocated to index groups proportionally based on their configured diskSpaceWeight. Disk space will be allocated to each index group according to the formula below, this will then be shared equally between the indicies in the index group (the configured maxIndicesRetained):

# Total disk space allocated to an index group
index_group_disk_space = (elasticsearchdiskSpaceMB* diskSpaceWeight / sum(diskSpaceWeights)

# Disk space available to each index in an index group
index_disk_space = index_group_disk_space / maxIndicesRetained

For example, with elasticsearchDiskSpaceMB = 300000, disk space would be allocated to the index groups and indexes be as follows:

Parameter	Index group disk space	Index disk space
kafkaMetricsToES.elasticsearch.index { diskSpaceWeight = 0 maxIndicesRetained = 20 }	0MB	0MB
kafkaMultiMetricsToES.elasticsearch.index { diskSpaceWeight = 1 maxIndicesRetained = 20 }	20000MB (or 300000*1/15)	1000MB (or 20000/20)
kafkaGenericEventsToES.elasticsearch.index{ diskSpaceWeight = 2 maxIndicesRetained = 20 }	40000MB (or 300000*2/15)	2000MB (or 40000/20)
kafkaTopologyEventsToES.elasticsearch.index{ diskSpaceWeight = 3 maxIndicesRetained = 20 }	60000MB (or 300000*3/15)	3000MB (or 60000/20)
kafkaStateEventsToES.elasticsearch.index{ diskSpaceWeight = 4 maxIndicesRetained = 20 }	80000MB (or 300000*4/15)	4000MB (or 80000/20)
kafkaStsEventsToES.elasticsearch.index{ diskSpaceWeight = 5 maxIndicesRetained = 20 }	100000MB (or 300000*5/15)	5000MB (or 100000/20)
kafkaTraceToES.elasticsearch.index{ diskSpaceWeight = 0 maxIndicesRetained = 20 }	0MB	0MB

External data store

If you have configured your own data source to be accessed by StackState, the retention policy is determined by the metric/event store that you have connected.