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From Varun Kumar <varunkumar...@hotmail.com>
Subject Re: Partition Reassignment in Cloud
Date Fri, 21 Jun 2019 01:39:58 GMT
The idea is to expand the cluster, i.e increase the number of brokers and repartition the partition
to distribute the load. So at the end of process both the broker needs to be up and running.
Would like to know if it is possible to move disk/log.dir from one broker to another and updating
metadata(partition assignment) will work in all cases ? I tried this is Kafka 2.2 and it worked,
but not sure if there are any special cases where it might fail.
From: George Li <sql_consulting@yahoo.com.INVALID>
Sent: Friday, June 21, 2019 2:17 AM
To: dev
Subject: Re: Partition Reassignment in Cloud

The new broker host meta.properties file can have the broker.id set to the original broker_id
(with original host shutdown/decommission), the new host has the storage of the original host
(either by copying or by change the network storage mount from original to new host).  This
way, it saves time running reassignments to change old_broker_id => new_broker_id ?

    On Wednesday, June 19, 2019, 9:19:58 PM PDT, Varun Kumar <varunkumar_94@hotmail.com>


I have been trying a small experiment with partition reassignment in cloud. where instead
of copying data between brokers using network, I moved the disk between the 2 brokers and
ran the partition reassignment. This actually increased the speed of partition reassignment
significantly. (As it had to catchup/fetch only down time data)

I tried this experiment this in Kafka 2.2.1 and it worked. I validated the data-consistency
using "kafka-replica-verification.sh" script.

Few more details of the experiment:

  *  Both the brokers from and to which the partitions are moving had to be shutdown.
  *  All the partitions in the disk are moved at once to new broker.
  *  Had to update broker.id property in meta.properties file for the moved log directory
before broker restart .
  *  Had to re-balance Leaders after brokers restart.

Can you please let me know if this approach will work in production ? Is there any scenario
where it might truncate/delete all data in moved disk and copy complete partition over network


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