kafka追加日志时报错，直接down掉?

[2018-06-13 08:41:29,339] FATAL [Replica Manager on Broker 1]: Halting due to unrecoverable I/O error while handling produce request:  (kafka.server.ReplicaManager)
kafka.common.KafkaStorageException: I/O exception in append to log '__consumer_offsets-5'



Caused by: java.io.FileNotFoundException: /tmp/kafka-logs/__consumer_offsets-5/00000000000000000000.index (没有那个文件或目录)

我重启kafka后，在对应的日志文件目录中就有了__consumer_offsets-5/00000000000000000000.index这个文件，很好奇log.dir这个配置(保存日志数据的目录)，为什么会报这个错误?