[Gluster-devel] ZkFarmer

Ian Latter ian.latter at midnightcode.org
Mon May 7 22:17:41 UTC 2012

Is there anything written up on why you/all want every
node to be completely conscious of every other node?

I could see a couple of architectures that might work
better (be more scalable) if the config minutiae were 
either not necessary to be shared or shared in only 
cases where the config minutiae were a dependency.

RE ZK, I have an issue with it not being a binary at
the linux distribution level.  This is the reason I don't
currently have Gluster's geo replication module in
place ..

----- Original Message -----
>From: "Jeff Darcy" <jdarcy at redhat.com>
>To: <gluster-devel at nongnu.org>
>Subject:  [Gluster-devel] ZkFarmer
>Date: Mon, 07 May 2012 10:43:47 -0400
> I've long felt that our ways of dealing with cluster
membership and staging of
> config changes is not quite as robust and scalable as we
might want.
> Accordingly, I spent a bit of time a couple of weeks ago
looking into the
> possibility of using ZooKeeper to do some of this stuff. 
Yeah, it brings in a
> heavy Java dependency, but when I looked at some
lighter-weight alternatives
> they all seemed to be lacking in more important ways. 
Basically the idea was
> to do this:
> * Set up the first N (e.g. N=3) nodes in our cluster as
ZooKeeper servers, or
> point everyone at an existing ZooKeeper cluster.
> * Use ZK ephemeral nodes as a way to track cluster
membership ("peer probe"
> merely updates ZK, and "peer status" merely reads from it).
> * Store config information in ZK *once* instead of
regenerating volfiles etc.
> on every node (and dealing with the ugly cases where a
node was down when the
> config change happened).
> * Set watches on ZK nodes to be notified when config
changes happen, and
> respond appropriately.
> I eventually ran out of time and moved on to other things,
but this or
> something like it (e.g. using Riak Core) still seems like
a better approach
> than what we have.  In that context, it looks like
ZkFarmer[1] might be a big
> help.  AFAICT someone else was trying to solve almost
exactly the same kind of
> server/config problem that we have, and wrapped their
solution into a library.
>  Is this a direction other devs might be interested in
pursuing some day,
> if/when time allows?
> [1] https://github.com/rs/zkfarmer
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Ian Latter
Late night coder ..

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