Managing Storage Locations
Vertica storage locations are paths to file destinations that you designate to store data and temporary files. Each cluster node requires at least two storage locations: one to store data, and another to store database catalog files. You set up these locations as part of installation and setup. (See Prepare Disk Storage Locations in Installing Vertica for disk space requirements.)
Important: While no technical issue prevents you from using CREATE LOCATION to add one or more Network File System (NFS) storage locations, Vertica does not support NFS data or catalog storage except for MapR mount points. You will be unable to run queries against any other NFS data. When creating locations on MapR file systems, you must specify ALL NODES SHARED.
How Vertica Uses Storage Locations
When you add data to the database or perform a DML operation, the new data is typically held in memory (WOS) and moved to storage locations on disk (ROS) at regular intervals. Depending on the configuration of your database, many ROS containers are likely to exist.
You can label the storage locations that you create, in order to reference them for object storage policies. If an object has no storage policy associated with it, Vertica uses default storage algorithms to store its data in available storage locations. If the object has a storage policy, Vertica stores the data at the object's designated storage location. You can can retire or drop store locations when you no longer need them.
Local Storage Locations
By default, Vertica stores data in unique locations on each node. Each location is in a directory in a file system that the node can access, and is often in the node’s own file system. You can create a local storage location for a single node or for all nodes in the cluster. Cluster-wide storage locations are the most common type of storage. Vertica defaults to using a local cluster-wide storage location for storing all data. If you want it to store data differently, you must create additional storage locations.
Shared Storage Locations
You can create shared storage locations, where data is stored on a single file system to which all cluster nodes in the cluster have access. This shared file system is often hosted outside of the cluster, such as on a distributed file system like HDFS. When you create a shared storage location, each node in the Vertica cluster creates its own subdirectory in the location. The separate directories prevent nodes from overwriting each other's data. Currently, Vertica supports only HDFS shared storage locations. You cannot use NFS as a Vertica shared storage location except when using MapR mount points. See Vertica Storage Location for HDFS in Integrating with Apache Hadoop for more information.
For databases running in Eon Mode, the STORAGE_LOCATIONS system table shows a third type of location, communal.
