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From "Chris K Wensel (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-2410) Make EC2 cluster nodes more independent of each other
Date Fri, 28 Mar 2008 02:16:24 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-2410?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12582880#action_12582880
] 

Chris K Wensel commented on HADOOP-2410:
----------------------------------------

This patch represents a fair number of changes and will need accompanying documentation. 

The typical usecase is this:

> hadoop-ec2 launch-cluster my-group 5
> hadoop-ec2 push my-group path/to/some.jar
> hadoop-ec2 login my-group
> hadoop-ec2 terminate-cluster my-group

In another window (after launch-cluster), this is quite useful, and works will with FoxyProxy:
> hadoop-ec2 proxy my-group

There are still some rough edges I think.

> hadoop-ec2
Usage: hadoop-ec2 COMMAND
where COMMAND is one of:
  list                                 list all running Hadoop EC2 clusters
  launch-cluster <group> <num slaves>  launch a cluster of Hadoop EC2 instances
- launch-master then launch-slaves
  launch-master  <group>               launch or find a cluster master
  launch-slaves  <group> <num slaves>  launch the cluster slaves
  terminate-cluster                    terminate all Hadoop EC2 instances
  login  <group|instance id>           login to the master node of the Hadoop EC2 cluster
  screen <group|instance id>           start or attach 'screen' on the master node of
the Hadoop EC2 cluster
  proxy  <group|instance id>           start a socks proxy on localhost:6666 (use w/foxyproxy)
  push   <group> <file>                scp a file to the master node of the Hadoop
EC2 cluster
  <shell cmd> <group|instance id>      execute any command remotely on the master
  create-image                         create a Hadoop AMI

> Make EC2 cluster nodes more independent of each other
> -----------------------------------------------------
>
>                 Key: HADOOP-2410
>                 URL: https://issues.apache.org/jira/browse/HADOOP-2410
>             Project: Hadoop Core
>          Issue Type: Improvement
>          Components: contrib/ec2
>    Affects Versions: 0.16.1
>            Reporter: Tom White
>         Attachments: concurrent-clusters.patch
>
>
> The cluster start up scripts currently wait for each node to start up before appointing
a master (to run the namenode and jobtracker on), and copying private keys to all the nodes,
and writing the private IP address of the master to the hadoop-site.xml file (which is then
copied to the slaves via rsync). Only once this is all done is hadoop started on the cluster
(from the master). This can fail if any of the nodes fails to come up, which can happen as
EC2 doesn't guarantee that you get a cluster of the size you ask for (I've seen this happen).
> The process would be more robust if each node was told the address of the master as user
metadata and then started its own daemons. This is complicated by the fact that the public
DNS alias of the master resolves to a public IP address so cannot be used by EC2 nodes (see
http://docs.amazonwebservices.com/AWSEC2/2007-08-29/DeveloperGuide/instance-addressing.html).
Instead we need to use a trick (http://developer.amazonwebservices.com/connect/message.jspa?messageID=71126#71126)
to find the private IP, and what's more we need to attempt to resolve the private IP in a
loop until it is available since the DNS will only be set up after the master has started.
> This change will also mean the private key doesn't need to be copied to each node, which
can be slow and has dubious security. Configuration can be handled using the mechanism described
in HADOOP-2409.

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