Managing disk space

Vertica detects and reports low disk space conditions in the log file so you can address the issue before serious problems occur.

1: Adding disk space to a node
2: Replacing failed disks
3: Catalog and data files
4: Understanding the catalog directory
5: Reclaiming disk space from deleted table data

Vertica detects and reports low disk space conditions in the log file so you can address the issue before serious problems occur. It also detects and reports low disk space conditions via SNMP traps if enabled.

Critical disk space issues are reported sooner than other issues. For example, running out of catalog space is fatal; therefore, Vertica reports the condition earlier than less critical conditions. To avoid database corruption when the disk space falls beyond a certain threshold, Vertica begins to reject transactions that update the catalog or data.

Caution

A low disk space report indicates one or more hosts are running low on disk space or have a failing disk. It is imperative to add more disk space (or replace a failing disk) as soon as possible.

When Vertica reports a low disk space condition, use the DISK_RESOURCE_REJECTIONS system table to determine the types of disk space requests that are being rejected and the hosts on which they are being rejected.

To add disk space, see Adding disk space to a node. To replace a failed disk, see Replacing failed disks.

Monitoring disk space usage

You can use these system tables to monitor disk space usage on your cluster:

System table	Description
`DISK_STORAGE`	Monitors the amount of disk storage used by the database on each node.
`COLUMN_STORAGE`	Monitors the amount of disk storage used by each column of each projection on each node.
`PROJECTION_STORAGE`	Monitors the amount of disk storage used by each projection on each node.

1 - Adding disk space to a node

This procedure describes how to add disk space to a node in the Vertica cluster.

Note

If you are adding disk space to multiple nodes in the cluster, then use the following procedure for each node, one node at a time.

To add disk space to a node:

If you must shut down the hardware to which you are adding disk space, then first shut down Vertica on the host where disk space is being added.
Add the new disk to the system as required by the hardware environment. Boot the hardware if it is was shut down.
Partition, format, and mount the new disk, as required by the hardware environment.
Create a data directory path on the new volume.

For example:
```
mkdir –p /myNewPath/myDB/host01_data2/
```
If you shut down the hardware, then restart Vertica on the host.
Open a database connection to Vertica and add a storage location to add the new data directory path. Specify the node in the CREATE LOCATION, otherwise Vertica assumes you are creating the storage location on all nodes.

See Creating storage locations in this guide and the CREATE LOCATION statement in the SQL Reference Manual.

2 - Replacing failed disks

If the disk on which the data or catalog directory resides fails, causing full or partial disk loss, perform the following steps:.

If the disk on which the data or catalog directory resides fails, causing full or partial disk loss, perform the following steps:

Replace the disk and recreate the data or catalog directory.
Distribute the configuration file (vertica.conf) to the new host. See Distributing Configuration Files to the New Host for details.
Restart the Vertica on the host, as described in Restart Vertica On Host.

See Catalog and data files for information about finding your DATABASE_HOME_DIR.

3 - Catalog and data files

For the recovery process to complete successfully, it is essential that catalog and data files be in the proper directories.

In Vertica, the catalog is a set of files that contains information (metadata) about the objects in a database, such as the nodes, tables, constraints, and projections. The catalog files are replicated on all nodes in a cluster, while the data files are unique to each node. These files are installed by default in the following directories:

/DATABASE_HOME_DIR/DATABASE_NAME/v_db_nodexxxx_catalog/ /DATABASE_HOME_DIR/DATABASE_NAME/v_db_nodexxxx_catalog/

Note

DATABASE_HOME_DIR is the path, which you can see from the Administration Tools. See Using the administration tools in the Administrator's Guide for details on using the interface.

To view the path of your database:

Run the Administration tools.
```
$ /opt/vertica/bin/admintools
```
From the Main Menu, select Configuration Menu and click OK.
Select View Database and click OK.
Select the database you want would like to view and click OK to see the database profile.

See Understanding the catalog directory for an explanation of the contents of the catalog directory.

4 - Understanding the catalog directory

The catalog directory stores metadata and support files for your database.

The catalog directory stores metadata and support files for your database. Some of the files within this directory can help you troubleshoot data load or other database issues. See Catalog and data files for instructions on locating your database's catalog directory. By default, it is located in the database directory. For example, if you created the VMart database in the database administrator's account, the path to the catalog directory is:

/home/dbadmin/VMart/v_vmart_nodennnn_catalog

where nodennnn is the name of the node you are logged into. The name of the catalog directory is unique for each node, although most of the contents of the catalog directory are identical on each node.

The following table explains the files and directories that may appear in the catalog directory.

Note

Do not change or delete any of the files in the catalog directory unless asked to do so by Vertica support.

File or Directory	Description
`bootstrap-catalog.log`	A log file generated as the Vertica server initially creates the database (in which case, the log file is only created on the node used to create the database) and whenever the database is restored from a backup.
`Catalog/`	Contains catalog information about the database, such as checkpoints.
`CopyErrorLogs/`	The default location for the COPY exceptions and rejections files generated when data in a bulk load cannot be inserted into the database. See Handling messy data for more information.
`DataCollector/`	Log files generated by the Data collector.
`debug_log.conf`	Debugging information configuration file. For Vertica use only.
`Epoch.log`	Used during recovery to indicate the latest epoch that contains a complete set of data.
`ErrorReport.txt`	A stack trace written by Vertica if the server process exits unexpectedly.
`Libraries/`	Contains user defined library files that have been loaded into the database See Developing user-defined extensions (UDxs). Do not change or delete these libraries through the file system. Instead, use the CREATE LIBRARY, DROP LIBRARY, and ALTER LIBRARY statements.
`Snapshots/`	The location where backups are stored.
`tmp/`	A temporary directory used by Vertica's internal processes.
`UDxLogs/`	Log files written by user defined functions that run in fenced mode.
`vertica.conf`	The configuration file for Vertica.
`vertica.log`	The main log file generated by the Vertica server process.
`vertica.pid`	The process ID and path to the catalog directory of the Vertica server process running on this node.

5 - Reclaiming disk space from deleted table data

You can reclaim disk space from deleted table data in several ways:.

You can reclaim disk space from deleted table data in several ways: