You can specify how often the log file is flushed to disk using the /lc option:
fs /d dbase.ref /l logfilename /lc nnn
where nnn specifies the number of records that are written to the log file before the Fileshare Server calls the operating system to flush the log file buffers to disk. The default value is 100, that is, the Fileshare Server flushes the log file to disk after each set of 100 records are written to it. In addition, the Fileshare Server automatically flushes the log file after every successful COMMIT operation.
The Fileshare Server is unable to flush a log file if the log file is not on the machine where the Fileshare Server is running or if the operating system does not allow Fileshare to force the log file to be flushed. In this situation, the "/lc 1" option forces the Fileshare Server to specify writethrough when opening the log file. The log file is then written to disk if the operating system supports writethrough on files.