[infinispan-dev] Suppressing state transfer via JMX

[Erik Salter]

I'd like something similar.  If I have equal keys on two machines (given an
orthogonal setup and a TACH), I'd like to suppress state transfer and run
with only one copy until I can recover my machines.  The business case is
that in a degraded scenario, additional replicas aren't going to buy me
anything, as a failure will most likely be at the machine level and will
cause me to lose data.  Once I've recovered the other machine, I can turn
back on state transfer to get my data redundancy.

Erik

-----Original Message-----
From: infinispan-dev-bounces at lists.jboss.org
[mailto:infinispan-dev-bounces at lists.jboss.org] On Behalf Of Mircea Markus
Sent: Tuesday, June 04, 2013 5:44 AM
To: infinispan -Dev List
Subject: Re: [infinispan-dev] Suppressing state transfer via JMX

Manik, what's wrong with Dan's suggestion with clearing the cache before
shutdown?

On 31 May 2013, at 14:20, Manik Surtani <msurtani at redhat.com> wrote:

>> 
>> If we only want to deal with full cluster shutdown, then I think stopping
all application requests, calling Cache.clear() on one node, and then
shutting down all the nodes should be simpler. On start, assuming no cache
store, the caches will start empty, so starting all the nodes at once and
only allowing application requests when they've all joined should also work
without extra work.
>> 
>> If we only want to stop a part of the cluster, suppressing rebalancing
would be better, because we wouldn't lose all the data. But we'd still lose
the keys whose owners are all among the nodes we want to stop. I've
discussed this with Adrian, and we think if we want to stop a part of the
cluster without losing data we need a JMX operation on the coordinator that
will "atomically" remove a set of nodes from the CH. After the operation
completes, the user will know it's safe to stop those nodes without losing
data.
> 
> I think the no-data-loss option is bigger scope, perhaps part of
ISPN-1394.  And that's not what I am asking about.
> 
>> When it comes to starting a part of the cluster, a "pause rebalancing"
option would probably be better - but again, on the coordinator, not on each
joining node. And clearly, if more than numOwner nodes leave while
rebalancing is suspended, data will be lost.
> 
> Yup.  This sort of option would only be used where data loss isn't an
issue (such as a distributed cache).  Where data loss is an issue, we'd need
more control - ISPN-1394.
> 

Cheers,
-- 
Mircea Markus
Infinispan lead (www.infinispan.org)





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