Re: [Bigdata-developers] Why zookeeper?

[Bryan T. <br...@sy...>]

What if the operation succeeds for some services but not for all and is therefore reperformed by the bind service. If the service for which it succeeds continues to behave as a group member then it is a problem since you now have N+1 members, or at least one service which not everyone believes is a member. Bryan 

> -----Original Message-----
> From: Fred Oliver [mailto:fko...@gm...] 
> Sent: Tuesday, August 03, 2010 2:32 PM
> To: Bryan Thompson
> Cc: Bigdata Developers
> Subject: Re: [Bigdata-developers] Why zookeeper?
> 
> Bryan,
> 
> > I also do not see how this service can be stateless.  It 
> needs to know how many instances of the logical services 
> exist, how many need to be created, and it needs to bind 
> physical instances to logical instances in a manner which 
> protects against network partitions.  That assignment really 
> needs to be either static or governed by zookeeper in order 
> to ensure that we do not assign too many instances to a quorum.
> 
> The number of physical instances per logical instance would 
> be a configuration parameter. The number of logical services 
> to be created is the number of unbound physical services 
> discovered divided by that parameter (provided the 
> rack/network awareness, etc. constraints are met). For a 
> group size of N, collect N compatible unbound physical 
> services to be a group, make a list of the ids, and send that 
> list to each group member along with the logical id in a 
> "bind" command. The newly bound services re-register with the 
> new information. I don't see where any question of "too many" 
> comes up.
> 
> Fred
>