Like Lars, I too was under the wrong impression about this configfs "nodemanager" kernel component. Our discussions in the cluster meeting Monday and Tuesday were assuming it was a general service that other kernel components could/would utilize and possibly also something that could send uevents to non-kernel components wanting a std. way to see membership information/events.
As to kernel components without corresponding user-level "managers", look no farther than OpenSSI. Our hope was that we could adapt to a user-land membership service and this interface thru configfs would drive all our kernel subsystems.
Bruce Walker
OpenSSI Cluster project
-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Lars Marowsky-Bree
Sent: Wednesday, July 20, 2005 9:27 AM
To: David Teigland
Cc: [email protected]; [email protected]; [email protected]
Subject: [Linux-cluster] Re: [Ocfs2-devel] [RFC] nodemanager, ocfs2, dlm
On 2005-07-20T11:35:46, David Teigland <[email protected]> wrote:
> > Also, eventually we obviously need to have state for the nodes -
> > up/down et cetera. I think the node manager also ought to track this.
> We don't have a need for that information yet; I'm hoping we won't
> ever need it in the kernel, but we'll see.
Hm, I'm thinking a service might have a good reason to want to know the possible list of nodes as opposed to the currently active membership; though the DLM as the service in question right now does not appear to need such.
But, see below.
> There are at least two ways to handle this:
>
> 1. Pass cluster events and data into the kernel (this sounds like what
> you're talking about above), notify the effected kernel components,
> each kernel component takes the cluster data and does whatever it
> needs to with it (internal adjustments, recovery, etc).
>
> 2. Each kernel component "foo-kernel" has an associated user space
> component "foo-user". Cluster events (from userland clustering
> infrastructure) are passed to foo-user -- not into the kernel.
> foo-user determines what the specific consequences are for foo-kernel.
> foo-user then manipulates foo-kernel accordingly, through user/kernel
> hooks (sysfs, configfs, etc). These control hooks would largely be specific to foo.
>
> We're following option 2 with the dlm and gfs and have been for quite
> a while, which means we don't need 1. I think ocfs2 is moving that
> way, too. Someone could still try 1, of course, but it would be of no
> use or interest to me. I'm not aware of any actual projects pushing
> forward with something like 1, so the persistent reference to it is somewhat baffling.
Right. I thought that the node manager changes for generalizing it where pushing into sort-of direction 1. Thanks for clearing this up.
Sincerely,
Lars Marowsky-Brée <[email protected]>
--
High Availability & Clustering
SUSE Labs, Research and Development
SUSE LINUX Products GmbH - A Novell Business -- Charles Darwin
"Ignorance more frequently begets confidence than does knowledge"
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