Recommended Settings for Planned Shutdown
Explains the modalities of a planned shutdown.
The HPE Ezmeral Data Fabric stack improves the latencies for planned shutdowns by implementing a fast failover mechanism where different services respond to the intimation of a failure.
Notifying CLDB to Allow Fast Failover
When planning to shutdown a node, notifying CLDB of an impending shutdown allows CLDB to update the replication chain such that primary and intermediate containers, if any, are not on the node and re-assign VIPs on the node when the node actually goes down. This, in turn, allows clients to continue activities on available nodes.
MapR (v5.1) includes an argument, node
failover
, to the maprcli
command that notifies CLDB of impending node shutdown so that
CLDB can ensure that the specified node does not have any primary containers and intermediate
containers (in a cascaded chain), and VIPs are re-assigned.
Shutting Down a Node
To notify CLDB of a planned shutdown of a node:
- Enable the fast failover behavior.
Refer to Enabling Fast Failover for more information.
- Reset the value of tcp_syn_retries parameter.
Refer to Tuning TCP for more information.
- (Optional) Get the hostname of the node to put in maintenance mode by running the
following command:
/opt/mapr/bin/maprcli node list -columns hostname
- Run the
failover
command for that node.For example:
Wait for few minutes (to allow containers to failover) before proceeding to the next step./opt/mapr/bin/maprcli node failover -nodes <node-hostname>
- Stop warden on that node by running the following command:
service mapr-warden stop
- Notify HPE Ezmeral Data Fabric that the node is in maintenance mode and when the maintenance task
is complete, remove the node from maintenance mode.
See Performing Maintenance on a Node for the commands to run to put and take a node out of maintenance mode.