Checking replication lag of nodes in a replica set
The most ideal state for a replica set is when all nodes within the cluster are in sync. In this recipe, we will look at how to check the replication lag of nodes in a replica set.
Getting ready
We will need at least a multinode replica set cluster. You can refer to the Adding a node in a replica set recipe in Chapter 4, High Availability with Replication, for more details.
How to do it...
- Ensure all nodes are up and connect to the primary node of the replica set using mongo shell.
- Fetch the current replication information:
rs.printReplicationInfo()- You should see output similar to this:
configured oplog size: 1578.62548828125MB log length start to end: 142363secs (39.55hrs) oplog first event time: Sun Oct 08 2017 18:54:12 GMT+0530 (IST) oplog last event time: Tue Oct 10 2017 10:26:55 GMT+0530 (IST) now: Tue Oct 10 2017 10:26:59 GMT+0530 (IST)
- Check the current replication information:
rs.printSlaveReplicationInfo()- You should see output similar to...
