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From Alejandro Fernandez <afernan...@hortonworks.com>
Subject Re: Change hostname on running cluster
Date Mon, 20 Apr 2015 19:53:58 GMT
Great writeup Benoit.  In Ambari 2.1.0, the host_name will exist in only the hosts table, and
all other tables will reference a host_id as FK.
https://issues.apache.org/jira/browse/AMBARI-10167

Thanks,
Alejandro

From: Benoit Perroud <benoit@noisette.ch<mailto:benoit@noisette.ch>>
Reply-To: "user@ambari.apache.org<mailto:user@ambari.apache.org>" <user@ambari.apache.org<mailto:user@ambari.apache.org>>
Date: Monday, April 20, 2015 at 12:42 PM
To: "user@ambari.apache.org<mailto:user@ambari.apache.org>" <user@ambari.apache.org<mailto:user@ambari.apache.org>>
Subject: Re: Change hostname on running cluster

I did it earlier this year with Ambari 1.7 and postgresql. As noticed earlier, no master processes
was running on the nodes I renamed.
Provided without guarantees : http://www.swiss-scalability.com/2015/01/rename-host-in-ambari-170.html



2015-04-19 13:22 GMT+02:00 Frank Eisenhauer <feisenhauer2@gmail.com<mailto:feisenhauer2@gmail.com>>:
Seems like renaming a host is more complex than expected, especially in my case, where I have
to rename the hosts with the master services like the namenode, hbase master etc.

I'm currently considering to install the test lab from scratch and migrate the "old" lab to
the newly installed one.





On Sunday, April 19, 2015, Alejandro Fernandez <afernandez@hortonworks.com<mailto:afernandez@hortonworks.com>>
wrote:
Renaming a host also has implications because NameNode and other services can still have references
to the old name in several configs.
If the host has no master components, then it's definitely easier.

The following steps can be used to change host name in the Ambari database, so please use
at your own risk.
1. Stop all services through Ambari UI.

2. Stop ambari-server on Ambari server host from command line, run:
> ambari-server stop

3. Stop ambari-agent on all of the hosts from command line, run:
> ambari-agent stop
This is done to make sure that operation safer.

4. Backup database on the Ambari server from command line, please run:
> mkdir /var/db_backup
> cd /var/db_backup

Postgres
> pg_dump -U ambari ambari > ambari1.sql (default password: bigdata)
> pg_dump -U mapred ambarirca > ambarirca1.sql (default password: mapred)

MySQL
In Linux, the MySQL databases are stored in /var/lib/mysql by default.
> mysqldump -u ambari ambari > ambari1.sql (default password: bigdata)

5. Replace all occurrences of old hostname with new hostname.
For example:
> sed 's/old-hostname/new-hostname/g' ambari1.sql > ambari2.sql
> sed 's/old-hostname/new-hostname/g' ambarirca1.sql > ambarirca2.sql (not needed when
using MySQL)
Warning: Use tools that are appropriate for you. Please be careful to not accidentally replace
unintended strings in the database data.

6. Clean up Ambari database from command line, please run:
> ambari-server reset

7. Recreate Ambari database from command line, please run:
Postgres
> su postgres -c 'psql -c "drop database ambari" '
> su postgres -c 'psql -c "drop database ambarirca" '
> su postgres -c 'psql -c "create database ambari" '
> su postgres -c 'psql -c "create database ambarirca" '

MySQL
> mysql -u ambari -pbigdata  (or other password)
mysql> DROP DATABASE ambari;
mysql> CREATE DATABASE ambari;
mysql> exit;

8. Load into Ambari database with the modified database generated in step 5 and run the following
commands:
Postgres
> su postgres -c 'psql -f ambari2.sql -d ambari'
> su postgres -c 'psql -f ambarirca2.sql -d ambarirca'

MySQL
> mysql -u ambari -pbigdata ambari < ambari2.sql (default password: bigdata)

9. Start ambari-server on Ambari server host from command line, please run:
> ambari-server start

10. Start ambari-agent on all of the hosts from command line, please run:
> ambari-agent start

11. Verify that Ambari shows new host name.

12.Restart all services through Ambari UI, this will cause all components to pick up any changes
in configs.
Note: This procedure does not modify any database that is used by Hadoop components such as
Hive metastore database or Oozie database. If database access were granted to old hosts, you
may need to grant permissions to the new host before starting the Hadoop service.

Thanks,
Alejandro

On 4/18/15, 1:16 PM, "Yusaku Sako" <yusaku@hortonworks.com> wrote:

Just FYI...
What I've seen folks do is dump the database, keep a backup, replace all
occurrences of the old hostname to the new hostname in the dump file, then
reimport.

Yusaku

On 4/18/15 9:51 AM, "Sumit Mohanty" <smohanty@hortonworks.com> wrote:

+Alejandro

In theory, you can stop ambari-server, modify all occurrences of the
hostname and that should be it. There is not first class support for it.

Alejandro, did you look at the possibility of manually changing all host
names to rename a host
(https://issues.apache.org/jira/browse/AMBARI-10167)

-Sumit
________________________________________
From: Frank Eisenhauer <feisenhauer2@gmail.com>
Sent: Saturday, April 18, 2015 12:31 AM
To: Ambari User
Subject: Change hostname on running cluster

Hi All,

we have a running hadoop cluster where we unfortunately have a hostname
in uppercase, e.g. SRV-HADOOP01.BIGDATA.LOCAL.

As of Ambari 1.7 we are experiencing a lot of side effects which are
presumably caused by the hostnames in uppercase.

I would like to rename the particular hosts(e.g.
srv-hadoop01.bigdata.local), so that there are only hosts with lowercase
names in the cluster.

Is it possible to change the hostname? I came across a few blogs, but in
general renaming hostnames seems not to be recommended.

Has anyone performed a hostname change?

Many thanks in advance.




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