AUTO_LLOG configuration parameter

Use the AUTO_LLOG configuration parameter to automatically add logical logs in the specified dbspace to improve performance.

onconfig.std value
Not in the onconfig.std file.
default value if you created a server during installation
AUTO_LLOG 1,llog,max_size
The max_size value depends on the value of the AUTO_TUNE_SERVER_SIZE configuration parameter.
values
0 = Default. Disabled. Logical logs are not automatically added to improve performance.
1,dbspace_name,max_size
  • 1 = Enabled. Logical logs are automatically added when needed to improve performance.
  • dbspace_name = The name of the dbspace in which to add logical log files. The dbspace must have the default page size for the operating system.
  • max_size = Optional. Default is 2048000 KB (2 GB). The maximum size, in KB, of all logical log files, including any logical log files that are not stored in the dbspace dbspace_name. When the maximum size is reached, the database server no longer adds logical log files to improve performance. If max_size is not specified, the AUTO_TUNE_SERVER_SIZE configuration parameter setting affects the maximum size. See the Usage section.
separators
Separate fields with a comma.
takes effect
After you edit your onconfig file and restart the database server.
When you reset the value dynamically in your onconfig file by running the onmode -wf command.
When you reset the value in memory by running the onmode -wm command.

Usage

If you created a server during installation, the AUTO_LLOG configuration parameter is enabled automatically. A dbspace that is named llog is created for logical logs. The installation program sets the initial size and value of the max_size option of the dbspace based on the value of the AUTO_TUNE_SERVER_SIZE configuration parameter. You can change the max_size option by resetting the value of the AUTO_LLOG configuration parameter.

If you did not create a server during installation, you can enable the AUTO_LLOG configuration parameter to automatically add logical log files when the database server detects that adding logical log files improves performance. For optimal performance, choose a dbspace on a separate disk from the root dbspace and the physical log.

When the AUTO_LLOG configuration parameter is enabled, the database server adds logical logs when the lack of logical logs causes too high a percentage of checkpoints, blocking checkpoints, or long checkpoints.

When the maximum size of the logical log files is reached, logical log files are no longer added to improve performance. However, if the DYNAMIC_LOGS configuration parameter is enabled, logical logs are added to prevent transaction blocking. The settings of the DYNAMIC_LOGS and the AUTO_LLOG configuration parameters do not interact. Similarly, you can continue to manually add logical log files.

If the value of the max_size field is larger than the size of the specified dbspace, make sure that your storage pool has available space.

Example

The following setting enables the automatic addition of logical log files until size of all logical log files is 204800 KB and sets the dbspace for logical log files to llog:

AUTO_LLOG 1,llog,204800

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