[Linux-HA] resource group design question

Daniel X Moore dxm at sgi.com
Fri Oct 5 05:16:29 MDT 2007


Andrew Beekhof wrote:
>> We have resource groups that contain multiple resources that sometimes
>> need to be handled individually, and sometimes as a group.
>>
>> When starting or stopping a resource group, we want to be able to
>> perform the start/stop operation on all the members at the same time (ie
>> not stop a, stop b, stop c ... but stop a,b&c together.
> 
> as in you dont want to issue 3 commands or you want the stopping to
> occur in parallel?

Not sequentially or parallel, but in one invocation... eg, don't run:

	OCF_RESKEY_who=a plugin start
	OCF_RESKEY_who=b plugin start
	OCF_RESKEY_who=c plugin start

but something like:

	OCF_RESKEY_who="a b c" plugin start

> if the latter, can they start in parallel too?
> 
> if so, maybe you just need to set ordered=false for the group...

parallel would make life more difficult. But maybe something like 
aggregated=true, if such a thing existed.

> 
>> When adding a member to a group, we want to be able to start the
>> individual member
> 
> it you add it to the end, this is possible
> 
>> and be able to synchronize with the completion of the
>> removal.
>>
>> When removing a member, we want to be able to remove just that member
>> and be able to synchronize with the completion of the removal.
> 
> not sure i understand what you mean by "synchronize" in this context

we need to be able to remove the member (ie stop it), and know when it 
has stopped (if the resource wasn't running, the member would be 
considered to have "stopped").

> 
>> We also want to be able to update (reload) a set of members.
>>
>> So far, I have two approaches:
>>
>>         - have a single resource with a list of members.
>>         - have a resource group with a individual resources for members
>>
>> The first approach makes it easy to deal with all members together, the
>> second with individual members.
>>
>> Can anyone suggest a way to get a combination of these behaviours?


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  Daniel Moore                              dxm at sgi.com
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