Availability collection interval defaults

Jay Shaughnessy jshaughn at redhat.com
Mon Mar 5 16:58:08 UTC 2012



On 2/29/2012 12:22 PM, Jay Shaughnessy wrote:
>
> In [most likely] RHQ 4.4 there will be several improvements to 
> Availability collection and handling.  One of the major changes is 
> /Prioritized Availability Collection/.It means plugin developers can 
> optimize their types to set out of box availability collection 
> intervals.  And users can alter the interval at 
> template/group/resource granularities.  The inherent difficulty, like 
> other default metric enablement/collection interval settings, is how 
> to decide what the settings should be.Out of box we want to be 
> conservative while still being useful.
>
> There are two topics that need discussion, the built-in defaults and 
> how to approach the plugin-specific overrides.
>
> _*Built-In Defaults*_
> The current defaults are based on category; server types are set to 1 
> minute and service types to 5 minutes.This actually increases avail 
> checking as previously everything was 5 minutes.  These defaults are 
> not set in stone, they are just numbers I picked.
>
> The 1 minute server default aims to increase the avail checking on 
> types that are more likely to be important.  This affects a small 
> percentage of types and so far everyone has informally agreed that 
> this seems like a good setting. Of course plugin descriptors can 
> override the default.
>
> The 5 minute service default simply maintains the default avail scan 
> period from earlier versions, giving a nod to backward compatibility.  
> This setting can easily be debated.  Increasing the default to, say 10 
> or 15 minutes, would give immediate performance benefit out of box.  
> As the majority of resources would be checked less often.   This 
> raises a few fundamental questions:  Is slow avail checking even 
> useful?  is backward compatibility even relevant here?   Is a slow 
> default a good idea seeing that plugins can easily override the 
> defaults, and users can further optimize their settings?

The more I think about it the more I like the idea of a 10 minute 
Service default.  This gives us a blanket performance enhancement out of 
box, without, I think, much of a functional difference over a 5 minute 
default.  Plugin developers can override this on any types they see fit. 
And of course users can then customize intervals further,  any way they 
see fit. In the end I would think that resources the plugin developer or 
users consider critical, would be assigned intervals less than 5 
minutes.  I think perhaps the best scenario is a small number of 
relevant resources with fairly short intervals, and the rest with larger 
intervals.

>
> Note also that availability collection can now be disabled on a type, 
> out of box.  Which means that it will immediately be assigned the 
> avail of its parent.  This is likely appropriate for any component 
> that simply returns UP in its getAvailability() implementation.
>
>
> *_Plugin-specific Overrides_*
> To be clear, it is a goal that our most critical plugins be optimized 
> out of box to better today's performance, increase avail checking for 
> the most important resources and lessen or disable avail checking for 
> less important resources.  The question is, who knows what these 
> settings should be?  How do we go about making these setting changes?
>
> Please chime in with your thoughts.
>
> _______________________________________________
> rhq-devel mailing list
> rhq-devel at lists.fedorahosted.org
> https://fedorahosted.org/mailman/listinfo/rhq-devel



More information about the rhq-devel mailing list