Resizing depot caching capacity

Each node in an Eon database caches depot data in a predefined storage location.

Each node in an Eon database caches depot data in a predefined storage location. The storage location path depends on your Vertica installation's filesystem. By default, each node in a cluster can use up to 60 percent of disk space on the storage location's filesystem to cache depot data. You can change caching capacity with ALTER_LOCATION_SIZE, by specifying to a fixed size or a percentage of total disk space. The function can specify a single node, a subcluster, or all nodes in the database cluster. You can increase depot caching capacity for each node up to 80 percent.

In the following example, ALTER_LOCATION_SIZE increases depot caching capacity to 80 percent of disk space on the storage location's filesystem. The function supplies an empty string as the second (node-name) argument, so the change applies to all nodes:

Important

By default, depot caching capacity cannot exceed 80 percent of disk space on the store location file system; attempts to set it to a higher value return an error. Vertica requires at least 20 percent of disk space for the catalog, Data Collector tables, and temp files.

=> SELECT node_name, location_label, location_path, max_size, disk_percent FROM storage_locations WHERE location_usage = 'DEPOT' ORDER BY node_name;
    node_name     | location_label  |      location_path      |  max_size   | disk_percent
------------------+-----------------+-------------------------+-------------+--------------
 v_vmart_node0001 | auto-data-depot | /home/dbadmin/verticadb | 36060108800 | 70%
 v_vmart_node0002 | auto-data-depot | /home/dbadmin/verticadb | 36059377664 | 70%
 v_vmart_node0003 | auto-data-depot | /home/dbadmin/verticadb | 36060108800 | 70%
(3 rows)

=> SELECT alter_location_size('depot', '','80%');
 alter_location_size
---------------------
 depotSize changed.
(1 row)

=> SELECT node_name, location_label, location_path, max_size, disk_percent FROM storage_locations WHERE location_usage = 'DEPOT' ORDER BY node_name;
    node_name     | location_label  |      location_path      |  max_size   | disk_percent
------------------+-----------------+-------------------------+-------------+--------------
 v_vmart_node0001 | auto-data-depot | /home/dbadmin/verticadb | 41211552768 | 80%
 v_vmart_node0002 | auto-data-depot | /home/dbadmin/verticadb | 41210717184 | 80%
 v_vmart_node0003 | auto-data-depot | /home/dbadmin/verticadb | 41211552768 | 80%
(3 rows)

Rescaling depot capacity

When a database is revived on an instance with greater or lesser disk space than it had previously, Vertica evaluates the depot size settings that were previously in effect. If depot size was specified as a percentage of available disk space, Vertica proportionately rescales depot capacity. For example, if depot caching capacity for a given node was set to 70 percent, the revived node applies that setting to the new disk space and adjusts depot caching capacity accordingly. If depot capacity was set to a fixed size, Vertica applies that setting, unless doing so will consume more than 80 percent of available disk space. In that case, Vertica automatically adjusts depot size as needed.