nodetool setcachecapacity 

Set global key and row cache capacities in megabytes.

Set global key and row cache capacities in megabytes.

Synopsis 

$ nodetool <options> setcachecapacity -- <key-cache-capacity> <row-cache-capacity>
DataStax Enterprise 5.0 Installer No-Services and tarball installations:
installation_location/resources/cassandra/bin
Options
Short Long Description
-h --host Hostname or IP address.
-p --port Port number.
-pwf --password-file Password file path.
-pw --password Password.
-u --username Remote JMX agent username.
key-cache-capacity Maximum size in MB of the key cache in memory.
row-cache-capacity Maximum size in MB of the row cache in memory.
counter-cache-capacity Maximum size in MB of the counter cache in memory.
-- Separates an option from an argument that could be mistaken for a option.

Description 

The key-cache-capacity argument corresponds to the key_cache_size_in_mb parameter in the cassandra.yaml. Each key cache hit saves one seek and each row cache hit saves a minimum of two seeks. Devoting some memory to the key cache is usually a good tradeoff considering the positive effect on the response time. The default value is empty, which means a minimum of five percent of the heap in MB or 100 MB.

The row-cache-capacity argument corresponds to the row_cache_size_in_mb parameter in the cassandra.yaml. By default, row caching is zero (disabled).

The counter-cache-capacity argument corresponds to the counter_cache_size_in_mb in the cassandra.yaml. By default, counter caching is a minimum of 2.5% of Heap or 50MB.

The location of the cassandra.yaml file depends on the type of installation:
DataStax Enterprise 5.0 Installer-Services and package installations /etc/dse/cassandra/cassandra.yaml
DataStax Enterprise 5.0 Installer-No Services and tarball installations install_location/resources/cassandra/conf/cassandra.yaml
Cassandra package installations /etc/cassandra/cassandra.yaml
Cassandra tarball installations install_location/resources/cassandra/conf/cassandra.yaml