Starting Services after Rebooting OS

[#1]

Hi All,

After applying OS patches to Data nodes, the servers must be rebooted. Once the servers are rebooted, the hadoop services running on them are not automatically coming up. You have to manually go into Ambari and tell the services to start on that host.

What are some best practices and recommendations as to how to automatically bring up the hadoop services after an OS reboot?

[#2 · Accepted solution]

@Andrew Watson

Pls check this -

https://community.hortonworks.com/questions/4940/hdp-os-upgradepatching-best-practices.html

The hadoop services are intentionally made chkconfig off to not to get started after server reboots. This is generally avoided to make sure the services starts in the series they are defined. If not so then there might be communication issue between services.

[#3]

below is one example - https://docs.hortonworks.com/HDPDocuments/HDP2/HDP-2.3.0/bk_upgrading_hdp_manually/content/start-had...

Warning
Before you start HDFS on an HA system you must start the ZooKeeper service. If you do not start the ZKFC, there can be failures.

[#4]

@Andrew Watson

You could put up a script to check for the services and restart them for this period. But as @Sagar Shimpi pointed out, you might have to take care of some of the services.

Also ensure that dependent HDP dependent components like Java / Python are not upgraded during this patching. If they are to be, it needs to be tested ahead.