Why installation is not carried out in the same sequence as the start order of profiles?

[asurajpai]

Hi,

Just curious to know, why installation of profiles is not carried out in the same sequence as the recommended start order of profiles?

For eg. for cluster installation of 2 node and above, say for 5 node, we have the installation sequence as

1)Install the ZooKeeper and Cassandra clusters on first three hosts.

2)Install the Apigee Management Server on the first host, which also installs OpenLDAP and the Edge UI.

3)Install the Apigee Message Processor + Router on the second and third host.

4)Install the Apigee Analytics standalone on the fourth and fifth host.

But the start order is

• 1.ZooKeeper

• 2.Cassandra

• 3.OpenLDAP

• 4.Qpidd

• 5.PostgreSQL database

• 6.Management Server

• 7.Router

• 8.Message Processor

• 9.Qpid Server

• 10.Postgres Server

• 11.Apigee UI

Please let know why this confusion on the installation sequence and start sequence.

In case if I have stopped the cluster, then I would start the same way I would have installed?

[adas]

@asurajpai I don't understand the concern here. The installation of components matter in case a certain component is dependent on others. For example, management ui requires mgmt server, ldap, cassandra etc. Management server in turn requires zookeeper, cassandra and ldap. Similarly other components like message processors, routers, ax components etc require mgmt server and zookeeper for server registration purposes.

Coming to the start order, we need to make sure all the components the management server requires are up before we start the mgmt server for example zookeeper, ldap, cassandra etc. So that explains the order of start up scripts. This need not be same as the installation order as this has nothing to do with how and in which order the components were installed. When the micro kernel comes up it requires few services and components to be up and hence a certain sequence is maintained during startup and shutdown. I hope this answers your query.

[asurajpai]

Hi @arghya das, thanks for the detailed reply.

I totally agree with the ZooKeeper, Cassandra and OpenLDAP to be installed or started before we install or start Management Server.

Can you please help understand the need for starting the 4.Qpidd and 5.PostgreSQL database to be started before 6.Management Server, 7.Router and 8.Message Processor.

We could have started 4.Qpidd and 5.PostgreSQL just before 9.Qpid Server and 10.Postgres Server.

Please let know the START dependency of Management Server, Router & Message Processor on third party components Qpidd and PostgreSQL (not functionally)?

I agree that it is the recommended sequence and I need to adhere to it without questioning. :>).

But I strongly believe that there must be a valid reason associated with it.

[adas]

yes the qpid and postgresql order can be changed, it need not be done started in that order. All I am trying to say is that don't read too much into the start/stop sequence of the third party components. We just make sure they are up and running before the corresponding apigee components that depend on them. Does that andwer your question ?