SP_THRESHOLD configuration parameter

Use the SP_THRESHOLD configuration parameter to define the minimum amount of free kilobytes that can exist in a storage space before HCL Informix® automatically runs a task to expand the space, either by extending an existing chunk in the space or by adding a new chunk.

onconfig.std value
0 = No threshold. The trigger that runs the storage space monitoring (mon_low_storage) task for adding space when space is below the threshold is disabled.

1 - 50 = A threshold that is a percentage of free kilobytes in a storage space.

If the value is 50 or below, Informix interprets the value as a percentage (for example, 10 = 10 percent and 2.84 = 2.84 percent).

1000 to the maximum size of a chunk = A threshold that is either 1000 kilobytes or the maximum size of the chunk on the current platform.

If the value is 1000 or higher, Informix interprets the value as a specific number of kilobytes.

Values 50 - 1000 are not valid.

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.


When you set the SP_THRESHOLD configuration parameter to a valid value that is greater than 0, the built-in Scheduler task, mon_low_storage, runs automatically when the free space in a dbspace, temporary dbspace, sbspace, temporary sbspace, or blobspace falls below the threshold.

Suppose the value of the SP_THRESHOLD configuration parameter value is 5.5, which the server interprets as 5.5 percent. If a space runs low on free pages, and the free space percentage falls below 5.5 percent and remains below that level until the mon_low_storage task runs next, that task will attempt to expand the space. If the SP_THRESHOLD configuration parameter is set to 50000 and a space has fewer than 50000 free kilobytes, that space will be expanded the next time mon_low_storage task runs.

A value of 0 turns off the mon_low_storage task, and prevents the server from extending any space. However, a value of 0 does not affect the ability of the server to extend a space when all free pages are depleted and more are needed.

The value specified in the SP_THRESHOLD configuration parameter applies to all spaces belonging to the server.

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