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Re: [Linux-cluster] Interfacing csnap to cluster stack



On Thu, 2004-10-07 at 12:35, Daniel Phillips wrote:
> On Thursday 07 October 2004 02:07, David Teigland wrote:
> > - SM is almost exclusively designed for symmetric clustering
> > subsystems and almost exclusively for in-kernel use.
> 
> Hi Dave, 
> 
> The executive summary of your post is "my pristine, perfect service 
> manager is for symmetric systems only and keep yer steenking 
> client-server mitts away from it."
> 
> You may well be right that it is not suited to the task at hand.  My 
> interest was more in its notion of layered services than its 
> membership-oriented control methods and events (by the way, the 
> stop-start-finish terminology is still horribly broken, I thought you 
> were going to fix that).
> 
> > the server is by definition a single point of failure (something
> > absent from symmetric systems.) 
> 
> No.  The csnap server is not a single point of failure any more than a 
> DLM lock master is.  So either it is not a single point of failure, or 
> single points of failure are not absent from your gdlm, choose your 
> poison. 
> 
> > A prime example is NFS.  RM is able to monitor an NFS server and start
> > it on  another machine if it fails.  NFS is probably the model you
> > should follow if your system is asymmetric and you want to use RM.
> 
> NFS is an awful model.  It keeps almost all its state on the clients, 
> and it tries to inhale the entire recovery model into itself, with no 
> help from infrastructure.
> 
> In contrast, a csnap server keeps almost all its state persistently on 
> shared storage, and it is supposed to have a cluster infrastructure 
> around to help it do some global processing that is not appropriate for 
> it to undertake itself.  You seem to be arguing passionately that yours 
> is not the infrastructure we are looking for.  Fair enough, I'd hoped 
> for more.

Daniel,

Maybe you should describe what kind of help you are looking for
from the infrastructure?

Daniel


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