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From "Tibor Kiss (JIRA)" <j...@apache.org>
Subject [jira] Commented: (WHIRR-167) Improve bootstrapping and configuration to be able to isolate and repair or evict failing nodes on EC2
Date Wed, 09 Feb 2011 06:08:57 GMT

    [ https://issues.apache.org/jira/browse/WHIRR-167?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12992334#comment-12992334

Tibor Kiss commented on WHIRR-167:

Today I manage to rebuild the patch again.
Regarding MAX_STARTUP_RETRIES, normally a value higher than 1 is not practically useful because
in if some instance losses cannot be covered from one retry it can be considered severe enough
to manually intervene. Eventually somebody really wants to set up 
whirr.instance-templates-max-percent-failures=100% dn+tt
and really sacrifices more than one retries, it can be an option. But definitively not a recommended
one. Instead of this, a new feature to add additional nodes can be more effective, compared
to the possible loss of nodes. Because in my experience I saw that usually a failure to start
instance is a temporary situation. When this is the situation, if one retry is not enough
than probably a few seconds or minutes later the instance reservation and startup problems
disappear again. 

A value of 0 it also makes sense to switch off completely the retry mechanism. So I will made
a small change and add a new parameter.
with default value 1.

I also check the temporary keys.

> Improve bootstrapping and configuration to be able to isolate and repair or evict failing
nodes on EC2
> ------------------------------------------------------------------------------------------------------
>                 Key: WHIRR-167
>                 URL: https://issues.apache.org/jira/browse/WHIRR-167
>             Project: Whirr
>          Issue Type: Improvement
>    Affects Versions: 0.4.0
>         Environment: Amazon EC2
>            Reporter: Tibor Kiss
>            Assignee: Tibor Kiss
>             Fix For: 0.4.0
>         Attachments: whirr-167-1.patch, whirr-167-2.patch, whirr-167-3.patch, whirr-167-4.patch,
whirr-167-5.patch, whirr-integrationtest.tar.gz, whirr.log
> Actually it is very unstable the cluster startup process on Amazon EC2 instances. How
the number of nodes to be started up is increasing the startup process it fails more often.
But sometimes even 2-3 nodes startup process fails. We don't know how many number of instance
startup is going on at the same time at Amazon side when it fails or when it successfully
starting up. The only think I see is that when I am starting around 10 nodes, the statistics
of failing nodes are higher then with smaller number of nodes and is not direct proportional
with the number of nodes, looks like it is exponentialy higher probability to fail some nodes.
> Lookint into BootstrapCluterAction.java, there is a note "// TODO: Check for RunNodesException
and don't bail out if only a few " which indicated the current unreliable startup process.
So we should improve it.
> We could add a "max percent failure" property (per instance template), so that if the
number failures exceeded this value the whole cluster fails to launch and is shutdown. For
the master node the value would be 100%, but for datanodes it would be more like 75%. (Tom
White also mentioned in an email).
> Let's discuss if there are any other requirements to this improvement.

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