16.10 - About Protecting Transactions by Reserving Cylinders for Perm Space - Teradata Database

Teradata Database Administration

Product
Teradata Database
Release Number
16.10
Release Date
April 2018
Content Type
Administration
Publication ID
B035-1093-161K
Language
English (United States)

A transaction is aborted when it requires more space than is currently available for the requesting user. When you create a user or database, the system requests space on cylinders from the pool of free cylinders. To protect transactions, you can specify that a number of cylinders be reserved for transactions needing permanent space.

The number of free cylinders to keep in reserve for requests needing permanent space is determined by the File System field named “Cylinders Saved for PERM” in DBS Control (see “Cylinders Saved for PERM” in Utilities). When a statement requires space, this field determines allocation as described in the following table.

IF the statement
needs … AND there are… THEN the statement …
permanent space one or more free cylinders succeeds.
less than one free cylinder fails with a disk full error.
spool space more free cylinders than the amount specified in Cylinders Saved for PERM succeeds.
fewer free cylinders than the amount specified in Cylinders Saved for PERM fails with a disk full error.

This means that requests needing SPOOL space might fail more often than requests needing PERM space. This can be advantageous because failure of a request for spool space rarely involves a rollback.

To monitor and reallocate permanent disk space, you can use Teradata Viewpoint.