COMPATIBILITY FORCE_WRITETHRU enables the WRITETHRU filemode for all non-transaction files (including PREIMG files, which are transaction controlled but do not have a transaction log).
This option is off by default. Be sure to check your FairCom Server configuration file, as it might be enabled there.
Note: The performance impact of the WRITETHRU filemode depends on whether COMPATIBILITY PREV610A_FLUSH is enabled. See COMPATIBILITY PREV610A_FLUSH for details.