Message log wrapping overwrites existing messages at the beginning of the file with new messages upon reaching a maximum log size.
When you enable message log wrapping, as soon as the log file reaches the maximum size specified in the IQMsgMaxSize server property or the -iqmsgsz server startup switch, new messages are written at the beginning of the file. Existing messages are overwritten, line-by-line.
Message log wrapping is enabled by setting IQMsgMaxSize or -iqmsgsz to a value greater than zero (the default value of zero indicates there is no limit on the size of the message log file) and setting the IQMsgNumFiles server property or the -iqmsgnum server startup switch to zero (the default).
When wrapping is enabled, the tag <next msg insertion place> in the message log file tells you where new messages are being placed. Additional tags at the beginning and end of the file remind you that log wrapping is enabled, and that the last message in the file may not be the most recent one.