The debug directive is used to set the level of debugging in effect in the system. Production systems should have their debug level set to zero (i.e., turned off). This is the default. Legal values of the debug option are between 0-255. The most useful values are between 0 (off) and 3. Setting the debug level greater than 1 can have an adverse effect on the size of your log files, and on the system's ability to send heartbeats at rapid rates, thus affecting the cluster reliability.
The debug level of the system can also be specified on the command line using the -d option. Additionally, the debug level of the system can be dynamically changed by sending the heartbeat process SIGUSR1 and SIGUSR2 signals. SIGUSR1 raises the debug level, and SIGUSR2 lowers it. A sample debug directive is shown below.