cloudera manager 的 server 提示 cloudera-scm-server dead but pid file exists？请大神解决

上周五CDH集群运行好好的，各个组件运行良好，今天周一早晨来之后发现挂掉了，启动cm的server一会儿后就挂掉，提示cloudera-scm-server dead but pid file exists，通过cloudera-scm-server.log日志提示：
ERROR ParcelUpdateService:com.cloudera.parcel.components.ParcelDownloaderImpl: Unable to retrieve remote parcel repository manifest
java.util.concurrent.ExecutionException: java.util.concurrent.TimeoutException: No response received after 10
at com.ning.http.client.providers.netty.NettyResponseFuture.get(NettyResponseFuture.java:223)
at com.cloudera.parcel.components.ParcelDownloaderImpl.getRepoInfoFromFuture(ParcelDownloaderImpl.java:563)
at com.cloudera.parcel.components.ParcelDownloaderImpl.getRepositoryInfo(ParcelDownloaderImpl.java:543)
at com.cloudera.parcel.components.ParcelDownloaderImpl.syncRemoteRepos(ParcelDownloaderImpl.java:357)
at com.cloudera.parcel.components.ParcelDownloaderImpl$1.run(ParcelDownloaderImpl.java:464)
at com.cloudera.parcel.components.ParcelDownloaderImpl$1.run(ParcelDownloaderImpl.java:459)
at com.cloudera.cmf.persist.ReadWriteDatabaseTaskCallable.call(ReadWriteDatabaseTaskCallable.java:36)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
Caused by: java.util.concurrent.TimeoutException: No response received after 10
at com.ning.http.client.providers.netty.NettyResponseFuture.get(NettyResponseFuture.java:215)
... 10 more
这是什么问题呢？该如何解决？