Back Up a Self-Managed Sharded Cluster with a Database Dump使用数据库转储备份自我管理的分片集群

Find a Backup Window查找备份窗口

To find a good time to perform a backup, monitor your application and database usage to find a time when chunk migrations, resharding, and schema transformation operations are unlikely to occur.为了找到一个执行备份的好时机，请监视应用程序和数据库使用情况，以找到不太可能发生块迁移、重新标记和模式转换操作的时间。

For more information, see Schedule Backup Window for a Self-Managed Sharded Cluster.有关更多信息，请参阅自我管理分片群集的计划备份窗口。

Stop the Balancer停止平衡器

To prevent chunk migrations from disrupting the backup, connect to mongos and use the sh.stopBalancer() method to stop the balancer:为了防止块迁移中断备份，请连接到mongos并使用sh.stopBalancer()方法停止平衡器：

sh.stopBalancer()

If a balancing round is in progress, the operation waits for balancing to complete.如果正在进行平衡回合，则操作将等待平衡完成。

To verify that the balancer is stopped, use the sh.getBalancerState() method:要验证平衡器是否已停止，请使用sh.getBalancerState()方法：

use config
while( sh.isBalancerRunning().mode != "off" ) {
   print( "Waiting for Balancer to stop..." );
   sleep( 1000 );
}

Lock the Cluster锁定集群

The sharded cluster must remain locked during the backup process to protect the database from writes, which may cause inconsistencies in the backup.在备份过程中，分片集群必须保持锁定状态，以保护数据库免受写入，这可能会导致备份不一致。

To lock a sharded cluster, connect to mongos and use the db.fsyncLock() method:要锁定分片集群，请连接到mongos并使用db.fsyncLock()方法：

db.getSiblingDB("admin").fsyncLock()

To confirm the lock, on mongos and the primary mongod of the config servers, run the following aggregation pipeline and ensure that all the shards are locked:要确认锁定，在配置服务器的mongos和主mongod上运行以下聚合管道，并确保所有分片都已锁定：

db.getSiblingDB("admin").aggregate( [
   {  $currentOp: { } },
   {  $facet: {
      "locked": [
         { $match: { $and: [
            { fsyncLock: { $exists: true } }
         ] } }],
       "unlocked": [
         { $match: { fsyncLock: { $exists: false } } }
       ]
   } },
   {  $project: {
      "fsyncLocked": { $gt: [ { $size: "$locked" }, 0 ] },
      "fsyncUnlocked": { $gt: [ { $size: "$unlocked" }, 0 ] }
   } }
 ] )

[ { fsyncLocked: true }, { fsyncUnlocked: false } ]

Take Backup备份

To back up the sharded cluster, use mongodump to connect to mongos and perform the backup:要备份分片集群，请使用mongodump连接到mongos并执行备份：

mongodump \
   --host mongos.example.net \
   --port 27017 \
   --username user \
   --password "passwd" \
   --out /opt/backups/example-cluster-1

Unlock the Cluster解锁集群

After the backup completes, you can unlock the cluster to allow writes to resume.备份完成后，您可以解锁群集以允许继续写入。

To unlock the cluster, use the db.fsyncUnlock() method:要解锁集群，请使用db.fsyncUnlock()方法：

db.getSibling("admin").fsyncUnlock()

To confirm the unlock, on mongos and the primary mongod of the config servers, run the following aggregation pipeline and ensure that all shards are unlocked:要确认解锁，请在配置服务器的mongos和主mongod上运行以下聚合管道，并确保所有分片都已解锁：

db.getSiblingDB("admin").aggregate( [
   {  $currentOp: { } },
   {  $facet: {
      "locked": [
         { $match: { $and: [
            { fsyncLock: { $exists: true } }
         ] } }],
       "unlocked": [
         { $match: { fsyncLock: { $exists: false } } }
       ]
   } },
   { $project: {
      "fsyncLocked": { $gt: [ { $size: "$locked" }, 0 ] },
      "fsyncUnlocked": { $gt: [ { $size: "$unlocked" }, 0 ] }
   } }
 ] )

[ { fsyncLocked: false }, { fsyncUnlocked: true } ]

Restart the Balancer重新启动平衡器

To restart the balancer, use the sh.startBalancer() method:要重新启动平衡器，请使用sh.startBalancer()方法：

sh.startBalancer()

To confirm that the balancer is running, use the sh.getBalancerState() method:要确认平衡器正在运行，请使用sh.getBalancerState()方法：

sh.getBalancerState()

true

The command returns true when the balancer is running.平衡器运行时，该命令返回true。