我管理一个小型的完全分布式的hadoop集群，我正在做日志的例行清理和检查。我看到一堆文件 .out 我配置的{hadoop\u home}/logs路径中的扩展。有以下几种：

hadoop-<my-system-name>-namenode-<my-system-name>.out
hadoop-<my-system-name>-namenode-<my-system-name>.out.1
hadoop-<my-system-name>-namenode-<my-system-name>.out.2
hadoop-<my-system-name>-datanode-<my-system-name>.out
hadoop-<my-system-name>-historyserver-<my-system-name>.out
hadoop-<my-system-name>-historyserver-<my-system-name>.out.2
hadoop-<my-system-name>-historyserver-<my-system-name>.out.3
hadoop-<my-system-name>-resourcemanager-<my-system-name>.out
hadoop-<my-system-name>-resourcemanager-<my-system-name>.out.1
hadoop-<my-system-name>-secondarynamenode-<my-system-name>.out
hadoop-<my-system-name>-secondarynamenode-<my-system-name>.out.1
hadoop-<my-system-name>-secondarynamenode-<my-system-name>.out.2

等等等等等等。
当我和编辑一起看其中一个的时候，比如 hadoop-<my-system-name>-namenode-<my-system-name>.out.1 文件，我得到：

core file size          (blocks, -c) unlimited
data seg size           (kbytes, -d) unlimited
scheduling priority             (-e) 0
file size               (blocks, -f) unlimited
pending signals                 (-i) 514997
max locked memory       (kbytes, -l) unlimited
max memory size         (kbytes, -m) unlimited
open files                      (-n) 16384
pipe size            (512 bytes, -p) 8
POSIX message queues     (bytes, -q) 819200
real-time priority              (-r) 0
stack size              (kbytes, -s) 8192
cpu time               (seconds, -t) unlimited
max user processes              (-u) 8092
virtual memory          (kbytes, -v) unlimited
file locks                      (-x) unlimited

这些文件是什么？它们是为了保留还是可以删除？