You can use a database option and a server startup switch to control insert and load messages.
Messages may display during insert and load operations. The NOTIFY_MODULUS database option adjusts the default frequency of notification messages during loads, or omits these message. The NOTIFY option in the LOAD command overrides the NOTIFY_MODULUS setting. See Reference: Statements and Options.
The IQMsgMaxSize server property and the -iqmsgsz server startup switch control message log wrapping and the size of the message log file.