[Linux-cluster] Interfacing csnap to cluster stack
Daniel McNeil
daniel at osdl.org
Thu Oct 7 22:57:14 UTC 2004
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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