Contrail Analytics DB data purge

Disk usage by analytics db can be monitored from the contrail UI page at
Monitor -> Infrastructure -> Database Nodes
or from database-node UVEs at
<analytics-node-ip>:8081/analytics/uves/database-node/*?cfilt=DatabaseUsageInfo

In an ideal scenario, the sizing should be done such that an external purging [as opposed to cassandra's own compaction] is not required.

When the above [ideal sizing] does not happen, one can rely on the following purge methods

contrail-analytics-api process continuously monitors the disk usage and tries to purge the data when it exceeds certain value.

If one needs to manually send a request to contrail-analytics-api, to purge beyond what it does automatically, it can be done from the UI using the grid's menu button at
Monitor -> Infrastructure -> Database Nodes
Another way to send a request to contrail-analytics-api to purge is to do a POST request to
<analytics-node-ip>:8081/analytics/operation/database-purge
the POST data is the percentage to purge and is input in JSON format, as below,
{ "purge_input" : 30 }

The above purge method is a slow process, as deleting the data from database does not immediately free up the disk space which depends on cassandra doing the compaction, which may depend on various factors including system load etc..
In extreme cases, where one needs to manually purge analytics data, one of the following methods can be used

Method 1: will save latest analytics data, but involves stopping cassandra on all nodes [this will disrupt config operations]
a) stop cassandra on all nodes [service contrail-database stop]
b) delete files /var/lib/cassandra/data/ContrailAnalytics that are older than some time on all database nodes
c) restart cassandra

Method 2: lose all analytics data, but cassandra can serve config operations
a) stop collectors on all nodes [service contrail-collector stop] b) using cqlsh or cassandra-cli - drop ContrailAnalytics keyspace [this will take a bit of time]
c) verify ContrailAnalytics keyspace is indeed not present in any node
d) delete /var/lib/cassandra/data/ContrailAnalytics directory
d) restart collectors