FYI ...

Tune logical and physical log automatically - http://www.iiug.org/Insider/insider_apr14.php#IC.1

Starting with version 12.10.xC3 Informix can automatically tune the logical and physical log as needed.

You can set the AUTO_LLOG configuration parameter to enable Informix to dynamically add logical logs when lack of logical logs causes frequent checkpoints, blocking checkpoints, long checkpoints etc. In addition, with AUTO_LLOG configuration parameter you can specify a dbspace in which to create new logical log files and the size of all logical log files at which the server stops adding logs for performance.
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Kind regards,
Vadim.