Automatic space management

You can configure the server to add more storage space automatically when more space is required. You use space more effectively and ensure that space is allocated as necessary, while reducing out-of-space errors. You reduce the time required to manually monitor your spaces to determine which storage space might run out of free space. If you configure the server to automatically add space, you can also manually expand a space or extend a chunk.

When the server expands a dbspace, temporary dbspace, sbspace, temporary sbspace, or blobspace, the server can add a chunk to the storage space. The server can also extend a chunk in a dbspace, plogspace, or temporary dbspace that is not mirrored. If the storage space is a non-mirrored dbspace or a temporary dbspace, the server can also extend a chunk in the storage space.

To configure for the automatic and manual space management, you run SQL administration API commands to perform these tasks:

  1. Create, modify, and delete one or more entries in the storage pool. The storage pool contains entries for available raw devices, cooked files, and directories that Informix® uses to expand a storage space.
  2. Mark a chunk as extendable.
  3. Modify the create and extend size of a storage space (optional).
  4. Change the threshold and wait time for the automatic addition of more space (optional).
  5. Configure the frequency of the monitor low storage task (optional).

If your storage pool contains entries, you can also run SQL administration API commands to:

  • Manually expand the storage space or extend a chunk, when you do not want to wait for the task that automatically expands the space to run.
  • Manually create storage spaces from storage pool entries and return space from empty storage spaces to the storage pool.

By default, the SP_AUTOEXPAND configuration parameter is set to 1 to enable automatic expansion of storage spaces. If you do not want to the server to automatically expand space, set the SP_AUTOEXPAND configuration parameter to 0 to disable the automatic creation or extension of chunks. You can also specify that a chunk is not extendable.

Tip:

In some situations, the database server might not automatically expand a temporary dbspace that is listed in the DBSPACETEMP configuration parameter after you configured the server to automatically expand an existing storage space. If operations (such as an index build or sort) that use the temporary dbspace run out of space, you receive an out of space error. To work around this problem, you must manually add a chunk to the temporary dbspace or use a bigger temporary dbspace.

If you have a storage pool and the database server participates in Enterprise Replication, storage spaces that are necessary for replication are created automatically if needed when you define a replication server.