我的理解是 Percona Server for MongoDB(最新版本)已经使用 rocksdb 引擎编译。然而，当我设置标志以使用它时，服务无法启动。它以代码 100(未捕获的异常)退出，并且没有日志输出。有谁知道是什么原因造成的？提前致谢。

最佳答案

您可能会在日志中看到类似这样的内容:

2016-03-10T21:17:23.433-0600 I CONTROL  ***** SERVER RESTARTED *****
2016-03-10T21:17:23.435-0600 I ACCESS   Initialized External Auth Session
2016-03-10T21:17:23.437-0600 I CONTROL  [initandlisten] MongoDB starting : pid=1323 port=27017 dbpath=/var/lib/mongodb 64-bit host=ubuntu14
2016-03-10T21:17:23.437-0600 I CONTROL  [initandlisten] db version v3.0.8-1.3
2016-03-10T21:17:23.437-0600 I CONTROL  [initandlisten] git version: 354592f7850d8d113690f610049baec94812da2b
2016-03-10T21:17:23.437-0600 I CONTROL  [initandlisten] build info: Linux vps-trusty-x64-01 2.6.32-042stab112.15 #1 SMP Tue Oct 20 17:22:56 MSK 2015 x86_64 BOOST_LIB_VERSION=1_49
2016-03-10T21:17:23.437-0600 I CONTROL  [initandlisten] allocator: tcmalloc
2016-03-10T21:17:23.437-0600 I CONTROL  [initandlisten] options: { config: "/etc/mongod.conf", net: { bindIp: "127.0.0.1", port: 27017 }, processManagement: { pidFilePath: "/var/run/mongod.pid" }, storage: { dbPath: "/var/lib/mongodb", engine: "rocksdb", journal: { enabled: true } }, systemLog: { destination: "file", logAppend: true, path: "/var/log/mongodb/mongod.log" } }
2016-03-10T21:17:23.503-0600 I STORAGE  [initandlisten] exception in initAndListen: 28574 Cannot start server. Detected data files in /var/lib/mongodb created by storage engine 'mmapv1'. The configured storage engine is 'rocksdb'., terminating
2016-03-10T21:17:23.503-0600 I CONTROL  [initandlisten] dbexit:  rc: 100

如果是这样，问题是您已经启动了指定 rocksdb 引擎的服务器，而另一个存储引擎数据集仍在 dbpath 中。为了解决此问题，您需要从 dbpath 中删除文件才能使用新引擎。

如果您想要保留 MongoDB 中的现有数据，那么您首先要使用 mongodump 工具来备份可以使用 mongorestore 恢复的信息切换存储引擎并重新启动服务器后。

在 /etc/mongod.conf 中更改存储引擎后， 要以干净的 dbpath 开始，请发出以下命令(以根用户身份):

注意:这将永久删除存储在您的 MongoDB 数据库中的所有数据:

# service mongod stop
# rm -rf /var/lib/mongodb/*
# service mongod start

几秒钟后，您应该会在日志文件底部看到以下消息。

# tail /var/log/mongodb/mongod.log

2016-03-10T21:25:30.398-0600 I CONTROL  ***** SERVER RESTARTED *****
2016-03-10T21:25:30.400-0600 I ACCESS   Initialized External Auth Session
2016-03-10T21:25:30.402-0600 I CONTROL  [initandlisten] MongoDB starting : pid=1530 port=27017 dbpath=/var/lib/mongodb 64-bit host=ubuntu14
2016-03-10T21:25:30.402-0600 I CONTROL  [initandlisten] db version v3.0.8-1.3
2016-03-10T21:25:30.402-0600 I CONTROL  [initandlisten] git version: 354592f7850d8d113690f610049baec94812da2b
2016-03-10T21:25:30.402-0600 I CONTROL  [initandlisten] build info: Linux vps-trusty-x64-01 2.6.32-042stab112.15 #1 SMP Tue Oct 20 17:22:56 MSK 2015 x86_64 BOOST_LIB_VERSION=1_49
2016-03-10T21:25:30.402-0600 I CONTROL  [initandlisten] allocator: tcmalloc
2016-03-10T21:25:30.402-0600 I CONTROL  [initandlisten] options: { config: "/etc/mongod.conf", net: { bindIp: "127.0.0.1", port: 27017 }, processManagement: { pidFilePath: "/var/run/mongod.pid" }, storage: { dbPath: "/var/lib/mongodb", engine: "rocksdb", journal: { enabled: true } }, systemLog: { destination: "file", logAppend: true, path: "/var/log/mongodb/mongod.log" } }
2016-03-10T21:25:30.808-0600 I NETWORK  [initandlisten] waiting for connections on port 27017

关于mongodb - 当引擎设置为 rocksdb (MongoRocks) 时，Percona Server for MongoDB 无法启动，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/35885878/