Storm in a Clustered Mode - Real-time Analytics with Storm and Cassandra - page 77

• <filenamepattern> : This is the pattern in which files are formed and rolled
over; for example, with the preceding code pattern, we have worker log files as
worker-6700.log and worker-6700.1.log .
• <minIndex> and <maxIndex> : These are very important in order to speci-
fy how many files we want to retain with this rolling appender; in this case, we
will have nine backup files, which are numbered from one to nine, and one run-
ning log file.
• maxFileSize : This parameter specifies at what size the file should rollover, for
instance, in our case, it's 100 MB; this means the worker log file will roll over to
the next index when it reaches this size.
• root level : This specifies the logging level; in our case, we have specified it
as Info , which means Info and the above logs will be printed in the log files, but
logs from levels below the Info level will not be written to the logs. The follow-
ing is the logging level hierarchy for reference:
◦ OFF
◦ FATAL
◦ ERROR
◦ WARN
◦ INFO
◦ DEBUG
◦ TRACE
◦ ALL