We are seeing logback leave .tmp files behind in the log directory, presumably due to a hiccup during log rotation or gzip. Size 2365956 Dec 11 00:00 statsreceiver.log.2010-12-10.gz 2679618 Dec 12 00:01 statsreceiver.log.2010-12-11.gz 9190879942 Dec 12 04:00 statsreceiver-debug.log23124507802228260.tmp 2542799 Dec 13 00:00 statsreceiver.log.2010-12-12.gz 9137740366 Dec 13 04:00 statsreceiver-debug.log23210907242250260.tmp 543937393 Dec 13 20:07 statsreceiver-debug.log.2010-12-13_19:00.gz 548781049 Dec 13 22:07 statsreceiver-debug.log.2010-12-13_21:00.gz 2284216 Dec 14 00:00 statsreceiver.log.2010-12-13.gz 8127562 Dec 15 00:00 statsreceiver.log.2010-12-14.gz 19067117496 Dec 15 13:00 statsreceiver-debug.log23416102512001260.tmp 18177324477 Dec 15 16:00 statsreceiver-debug.log23426920509229260.tmp 2257423 Dec 15 23:00 statsreceiver-debug.log.2010-12-15_22:00.gz The logback jar versions are: WEB-INF/lib/logback-classic-0.9.26.jar WEB-INF/lib/logback-core-0.9.26.jar There is only a single application writing to those files, though it is conceivable that the .tmp droppings correlate to restarts of that application. If this is expected on application restarts, then could logback start gzip'ing them again when it comes back? Here is the logback.xml file: <?xml version="1.0" encoding="UTF-8"?> <configuration scan="true" scanPeriod="60 seconds"> <appender name="FILE_WARN" class="ch.qos.logback.core.rolling.RollingFileAppender"> <file>${logdir:-.}/${prog:-unknown}.log</file> <append>true</append> <filter class="ch.qos.logback.classic.filter.ThresholdFilter"> <level>warn</level> </filter> <rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy"> <fileNamePattern>${logdir:-.}/${prog:-unknown}.log.%d{yyyy-MM-dd}.gz</fileNamePattern> <maxHistory>7</maxHistory> </rollingPolicy> <encoder> <pattern>%-30(%d{yyyy-MM-dd HH:mm:ss} %.-1level :) %m Context:[%X{GTNDC_INFO}]%n</pattern> </encoder> </appender> <appender name="FILE_DEBUG" class="ch.qos.logback.core.rolling.RollingFileAppender"> <file>${logdir:-.}/${prog:-unknown}-debug.log</file> <append>true</append> <filter class="ch.qos.logback.classic.filter.ThresholdFilter"> <level>debug</level> </filter> <rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy"> <fileNamePattern>${logdir:-.}/${prog:-unknown}-debug.log.%d{yyyy-MM-dd_HH:00}.gz</fileNamePattern> <maxHistory>36</maxHistory> </rollingPolicy> <encoder> <pattern>%-60(%d{yyyy-MM-dd HH:mm:ss} [%thread] %.-1level :) %m Context:[%X{GTNDC_INFO}]%n</pattern> </encoder> </appender> <logger name="org.apache.directory" level="WARN"/> <root><level value="debug"/> <appender-ref ref="FILE_WARN"/> <appender-ref ref="FILE_DEBUG"/> </root> </configuration>