Back Up a Self-Managed Sharded Cluster with File System Snapshots使用文件系统快照备份自我管理的分片群集

Find a Backup Window查找备份窗口

Chunk migrations, resharding, and schema migration operations can cause inconsistencies in backups. To find a good time to perform a backup, monitor your application and database usage and find a time when these operations are unlikely to occur.块迁移、重新标记和模式迁移操作可能会导致备份不一致。要找到执行备份的好时机，请监视应用程序和数据库使用情况，并找到不太可能发生这些操作的时间。

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, use the sh.stopBalancer() method to stop the balancer:为防止块迁移中断备份，请使用sh.stopBalancer()方法停止平衡器：

sh.stopBalancer()

If a balancing round is currently in progress, the operation waits for balancing to complete.如果当前正在进行平衡回合，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...");
   sleep(1000);
}

Lock the Cluster锁定集群

Writes to the database can cause backup inconsistencies. Lock your sharded cluster to protect the database from writes.写入数据库可能会导致备份不一致。锁定分片集群以保护数据库免受写入。

To lock a sharded cluster, use the db.fsyncLock() method:要锁定分片集群，请使用db.fsyncLock()方法：

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

Run the following aggregation pipeline on both mongos and the primary mongod of the config servers. 在配置服务器的mongos和主mongod上运行以下聚合管道。To confirm the lock, ensure that the fysncLocked field returns true and fsyncUnlocked field returns false.要确认锁定，请确保fysncLocked字段返回true，fsyncUnlocked字段返回false。

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 } ]

Back up the Primary Config Server备份主配置服务器

To create a filesystem snapshot of the config server, follow the procedure in Create a Snapshot.要创建配置服务器的文件系统快照，请按照创建快照中的过程进行操作。

Back up the Primary Shards备份主分片

Perform a filesystem snapshot against the primary member of each shard, using the procedure found in Back Up and Restore a Self-Managed Deployment with Filesystem Snapshots.使用使用文件系统快照备份和还原自我管理部署中的过程，对每个分片的主要成员执行文件系统快照。

Unlock the Cluster解锁集群

After the backup completes, you must unlock the cluster to allow writes to resume.备份完成后，您必须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()

Run the following aggregation pipeline on both mongos and the primary mongod of the config servers. 在配置服务器的mongos和主mongod上运行以下聚合管道。To confirm the unlock, ensure that the fysncLocked field returns false and fsyncUnlocked field returns true.要确认解锁，请确保fysncLocked字段返回false，fsyncUnlocked字段返回true。

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。