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https://issues.apache.org/jira/browse/ATLAS-511?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15185159#comment-15185159
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CASSIO DOS SANTOS commented on ATLAS-511:
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Hemanth Yamijala, you're right about what I meant by on "demand", lazy loading
is maybe a better way to refer to it.
Having said that, as Venkata Madugundu has considered in his comments,
evaluating the impact to performance of turning cache off is something that we
could maybe help with in the short term. I'd like to know your thoughts on
other options like the use of a distributed cache, or a cache with some
"refresh-if-obsolete" policy that would check for type timestamp in the backend
store to decide if a cached type needs to be refreshed, or a "refresh type"
broadcast to all instances. I agree we should use separate JIRAs from this one
to cover those different alternatives, and maybe have some investigative or
proof of concept work done in parallel on some of them.
> Ability to run multiple instances of Atlas Server with automatic failover to
> one active server
> ----------------------------------------------------------------------------------------------
>
> Key: ATLAS-511
> URL: https://issues.apache.org/jira/browse/ATLAS-511
> Project: Atlas
> Issue Type: Sub-task
> Reporter: Hemanth Yamijala
> Assignee: Hemanth Yamijala
> Attachments: HADesign.pdf
>
>
> One of the most important components that only supports active-standby mode
> currently is the Atlas server which hosts the API / UI for Atlas. As
> described in the [HA
> Documentation|http://atlas.incubator.apache.org/0.6.0-incubating/HighAvailability.html],
> we currently are limited to running only one instance of the Atlas server
> behind a proxy service. If the running instance goes down, a manual process
> is required to bring up another instance.
> In this JIRA, we propose to have an ability to run multiple Atlas server
> instances. However, as a first step, only one of them will be actively
> processing requests. To have a consistent terminology, let us call that
> server the *master*. Any requests sent to the other servers will be
> redirected to the master.
> When the master suffers a partition, one of the other servers must
> automatically become the master and start processing requests. What this mode
> brings us over the current system is the ability to automatically failover
> the Atlas server instance without any manual intervention. Note that this
> can be arguably called an [active/active
> setup|https://en.wikipedia.org/wiki/High-availability_cluster]
> ATLAS-488 raised to support multiple active Atlas server instances. While
> that would be ideal, we have to learn more about the underlying system
> behavior before we can get there, and hopefully we can take smaller steps to
> improve the system systematically. The method proposed here is similar to
> what is adopted in many other Hadoop components including HDFS NameNode,
> HBase HMaster etc.
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