log4j在服务器端不备份文件问题

[kkeennvviinn]

log4j.properties
配置为：
log4j.rootLogger = INFO,console,file
log4j.appender.console = org.apache.log4j.ConsoleAppender
#log4j.appender.console.layout = org.apache.log4j.SimpleLayout
log4j.appender.console.layout = org.apache.log4j.PatternLayout
log4j.appender.console.layout.ConversionPattern = %p %d (%c:%L) - %m%n
log4j.appender.file = org.apache.log4j.DailyRollingFileAppender
log4j.appender.file.File = E\:/log/xx/logs/xx.log
log4j.appender.file.DatePattern = '.'yyyy-MM-dd
log4j.appender.file.layout = org.apache.log4j.PatternLayout
log4j.appender.file.layout.ConversionPattern = %p %d (%c\:%L) - %m%n

在本地测试没有问题，在服务器上运行只生成当天文件，过期只覆盖，不备份，请指点