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From "David Harvey (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (IGNITE-9365) Force backups to different AWS availability zones using only Spring XML
Date Wed, 19 Sep 2018 03:59:00 GMT

    [ https://issues.apache.org/jira/browse/IGNITE-9365?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16620072#comment-16620072
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David Harvey commented on IGNITE-9365:
--------------------------------------

[~vkulichenko], the use case I thinking about is we have a working cluster, and a new node
is added to the baseline, but it is missing the attribute.      If the affinityBackupFilter
throws an exception,  there is nothing to catch all the way back to GridDhtPartitionsExchangeFuture.processFullMessage(),
and all nodes that tries to calculate() affinity will throw that exception.       For
this use case, we would want to validate that the node coming online has the proper attribute
set, and not discover this on an arbitrary node.   I don't have a complete enough understanding
to know where that validation should go.    

A more promising approach is to not allow a node with a null attribute to service _either_
the primary or backup.   That is, if you configure a cache with an affinityBackupFilter,
the set of nodes that can service that cache will be limited to nodes that will not throw
an exception if the filter is given the node and a list of nodes only containing that node. 
   I don't yet see how to handle the case where no nodes have the attribute, however.

> Force backups to different AWS availability zones using only Spring XML
> -----------------------------------------------------------------------
>
>                 Key: IGNITE-9365
>                 URL: https://issues.apache.org/jira/browse/IGNITE-9365
>             Project: Ignite
>          Issue Type: Improvement
>          Components: cache
>         Environment:  
>            Reporter: David Harvey
>            Assignee: David Harvey
>            Priority: Minor
>             Fix For: 2.7
>
>         Attachments: master_947962f785_availability_zones_via_spring.patch
>
>   Original Estimate: 168h
>  Remaining Estimate: 168h
>
> As a developer, I want to be able to force  cache backups each to a different "Availability
Zone", when I'm running out-of-the-box Ignite, without additional Jars installed.  "Availability
zone" is a AWS feature with different names for the same function by other cloud providers. 
A single availability zone has the characteristic that some or all of the EC2 instances in
that zone can fail together due to a single fault.   You have no control over the hosts
on which the EC2 instance VMs run on in AWS, except by controlling the availability zone .  
>  
> I could write a few lines of a custom affinityBackupFilter, and configure it a RendezvousAffinityFunction,
but then I have to get it deployed on all nodes in the cluster, and peer class loading will
not work to this.   The code to do this should just be part of Ignite. 
>  



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