Thoughts on…

Java Middleware & Systems Management

Cluster Management

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For a majority of the past year the RHQ team has worked diligently to deliver a stable, extensible, and fault tolerant infrastructure for managing and monitoring your enterprise. Most of the focus has been on providing services at the individual resource level – a singular Apache install, a sole IIS instance, a solitary JBoss Application Server. Nowadays, however, the name of the game is clustering. Redundant servers, clustered services, data replication, cloud computing – all have a slightly different role in the game.

There are plenty of companies out there trying to get in on the action, who have high hopes of becoming formidable players. In a similar vein, the next release of RHQ promises to make its platform technology a force to reckon with when it comes to managing and monitoring clustered resources. There are several key facets to this (in no particular order):

• aggregate and average views of metric / measurement data
• operational scheduling and execution
• fine-grained configuration control

The first two of these are actually partially implemented. Today, if you create a compatible group (a resource group that only contains a single type of resource, e.g. only JBossAS instances) you can schedule and execute operations against the members in the group, in rolling fashion or simultaneously against all of them, as well as view aggregate and average metrics.

The shortcoming here, however, is that you need to explicitly add resources to a compatible group before you can perform these aggregate business services across them. Manually adding resources to the group would be absurd for anything but the smallest inventories. This is largely why DynaGroups exist. They were created with the sole purpose of being able to create vast numbers of groups according to flexible rules for how to partition your resources.

So why isn’t this good enough? It’s because DynaGroups can not create hierarchies of grouped resources, such as a group of HTTP Connectors under a group of Embedded Tomcat Servers under a group of JBoss Application Servers. And this group-wise, hierarchical navigation is where a lot of the power will be derived from.

If you could aggregate your JBossAS instances into a cluster group, and then have logically clustered servers and services automatically grouped beneath that, you could navigate the resource hierarchy very quickly and efficiently. Instead of having to view data from multiple contexts, a “cluster view” would aggregate the data into a single, navigable tree structure – a single context. You wouldn’t be bouncing back and forth between different pages; everything would be at your fingertips from a single, landing page.

A secondary benefit of building cluster views – instead of explicitly using compatible groups – is that you won’t clog up your resource browser with thousands of groups you might use only rarely, if ever.

Think about this: let’s say we have 60 physical hosts, 5 JBossAS instances on each of them, 3 instances to a logical cluster, which creates 100 (60*5/3) cluster groups. Let’s further say that on each instance we have 250 unique business services (this includes enterprise applications, session & entity beans, connectors, virtual hosts, datasources, queues / topics, etc). If we were to create explicit compatible groups for all nested servers and services under each of these 100 cluster groups, it would be another 25K (250*100) groups.

The cost of group creation is not the worry here; it’s the sheer volume of groups that would be shown in the application’s user interface. If you had a handful of compatible groups that you were previously using to manage your inventory, say a dozen or two, it would be much more difficult and frustrating to sift through one- to two-thousand times as much data. Granted, a very nice search interface could mitigate the situation, but it wouldn’t eliminate the underlying problem of unnecessary group creation.

So the solution migrates back to our cluster view concept. The team has come together several times over the past 2 weeks to flesh out the details, and the current functional and user interface requirements have been kept updated on the RHQ Project site here. If you have ideas above and beyond what you see there, we encourage you to speak up and let us know how we can make the new features and product improvements around resource clustering even better. If you want to be part of the action and you’re interested in becoming a contributor to the RHQ Project, look for my handle – joseph42 – in #rhq on freenode.

As always, post backs are greatly appreciated.


Written by josephmarques

October 24, 2008 at 7:59 am

Posted in rhq

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2 Responses

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  1. Hello webmaster
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    March 3, 2009 at 10:58 am

    • My apologies for the delayed reply. Please, feel free to link to my blog.


      April 27, 2009 at 4:21 am

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