-v[spec]
    Sets logging levels. Without any spec, sets the log level for every module and facility to dbg. Otherwise, spec is a list of words separated by spaces or commas or colons, up to one from each category below:

    •   A valid module name, as displayed by the vlog/list command on ovs-appctl(8), limits the log level change to the specified module.

    •   syslog, console, or file, to limit the log level change to only to the system log, to the console, or to a file, respectively.

    •   off, emer, err, warn, info, or dbg, to control the log level. Messages of the given severity or higher will be logged, and messages of lower severity will be filtered out. off filters out all messages. See ovs-appctl(8) for a definition of each log level.

    Case is not significant within spec.

    Regardless of the log levels set for file, logging to a file will not take place unless --log-file is also specified (see below).

    For compatibility with older versions of OVS, any is accepted as a word but has no effect.

-v  Sets the maximum logging verbosity level, equivalent to --verbose=dbg.

-vPATTERN:facility:pattern
    Sets the log pattern for facility to pattern. Refer to ovs-appctl(8) for a description of the valid syntax for pattern.

--log-file[=file]
    Enables logging to a file. If file is specified, then it is used as the exact name for the log file. The default log file name used if file is omitted is @LOGDIR@/.log.