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Explorer
Posts: 14
Registered: ‎11-08-2017

How to migrate kudu tablets

Hi,

We have added extra tablet server to our cluster (CDH 5.12.1)

How can we easiest migrate/reassign kudu tablets to new tablet server?

 

Thank you in advance,

Cloudera Employee
Posts: 21
Registered: ‎02-23-2017

Re: How to migrate kudu tablets

Even in the latest release, it's not particularly easy to rebalance this situation, although this is a known issue that will be worked on soon. To do so today, you would need to do the following:

 

  1. Determine which tablets you want to move. E.g. you could run the `kudu remote_replica list` tool to list the tablets replicas on each tablet server and use whatever heuristic you want to pick select a subset of replicas to move over to the new tablet server, noting both the tablet id and the tablet server id that you want to migrate from. Then, for each such pair run:
  2. Run the `kudu tablet change_config move_replica` tool to copy the replica from the source tablet server over to you new tablet server.

This page has some more details that may be found helpful: https://kudu.apache.org/docs/command_line_tools_reference.html#change_config-move_replica

Explorer
Posts: 14
Registered: ‎11-08-2017

Re: How to migrate kudu tablets

Thank you for your reply, I have followed your instrutions, however I can not use kudu tablet change_config move_replica tool ( I got below message) 

 

Invalid argument: unknown command 'move_replica'
Usage: /opt/cloudera/parcels/KUDU-1.4.0-1.cdh5.12.1.p0.10/bin/../lib/kudu/bin/kudu tablet change_config <command> [<args>]

<command> can be one of the following:
add_replica Add a new replica to a tablet's Raft configuration
change_replica_type Change the type of an existing replica in a tablet's
Raft configuration
remove_replica Remove an existing replica from a tablet's Raft
configuration

 

Any ideas?

 

Explorer
Posts: 14
Registered: ‎11-08-2017

Re: How to migrate kudu tablets

Thank you for your reply, I have followed your instrutions, however I can not use kudu tablet change_config move_replica tool ( I got below message) 

 

Invalid argument: unknown command 'move_replica'
Usage: /opt/cloudera/parcels/KUDU-1.4.0-1.cdh5.12.1.p0.10/bin/../lib/kudu/bin/kudu tablet change_config <command> [<args>]

<command> can be one of the following:
add_replica Add a new replica to a tablet's Raft configuration
change_replica_type Change the type of an existing replica in a tablet's
Raft configuration
remove_replica Remove an existing replica from a tablet's Raft
configuration

 

Any ideas?

 

Cloudera Employee
Posts: 19
Registered: ‎11-12-2013

Re: How to migrate kudu tablets

Unfortunately the 'move_replica' tool is only available in CDH 5.13 and higher. You'll need to upgrade your cluster to use it.

Cloudera Employee
Posts: 19
Registered: ‎11-12-2013

Re: How to migrate kudu tablets

beata also raised this question on the Apache Kudu user mailing list, and Will Berkeley provided a more detailed answer.

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Explorer
Posts: 14
Registered: ‎11-08-2017

Re: How to migrate kudu tablets

Thank you for your answear. I have upgraded cluster and I can move replicas 

Explorer
Posts: 14
Registered: ‎11-08-2017

Re: How to migrate kudu tablets

Hi 

 

Do you know in which release would be easier to rebalance tablets replicas between servers instead of using move_replica tool per tablet replica?

 

thank you in advance

 

Kind regards 

Beata 

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