Guys,

I also heard complaints about absence of option to automatically change baseline topology. They absolutely make sense. What Pavel suggested will work as a workaround. I think, in future releases we should give user an option to enable a similar behavior via Ignite Configuration. It may be called "Baseline Topology change policy". I see it as rule-based language, which allows to specify conditions of BLT change using several parameters - timeout and minimum allowed number of partition copies left (maybe this option should be provided also on per-cache-group level). Policy can also specify conditions for including new nodes in BLT if they are present - including node attributes filters and so on.


What do you think?

Best Regards,
Ivan Rakov

On 12.04.2018 19:41, Pavel Kovalenko wrote:
Denis,

It's just one of the ways to implement it. We also can subscribe on node
join / fail events to properly track downtime of a node.

2018-04-12 19:38 GMT+03:00 Pavel Kovalenko <jokse...@gmail.com>:

Denis,

Using our API we can implement this task as follows:
Do each minute:
1) Get all alive server nodes consistent ids =>
ignite().context().discovery().aliveServerNodes() => mapToConsistentIds().
2) Get current baseline topology => ignite().cluster().
currentBaselineTopology()
3) For each node in baseline and not in alive server nodes check timeout
for this node.
4) If timeout is reached remove node from baseline
5) If baseline is changed set new baseline => ignite().cluster().
setNewBaseline()


2018-04-12 2:18 GMT+03:00 Denis Magda <dma...@apache.org>:

Pavel, Val,

So, it means that the rebalancing will be initiated only after an
administrator remove the failed node from the topology, right?

Next, imagine that you are that IT administrator who has to automate the
rebalancing activation if the node failed and not recovered within 1
minute. What would you do and what Ignite provides to fulfill the task?

--
Denis

On Wed, Apr 11, 2018 at 1:01 PM, Pavel Kovalenko <jokse...@gmail.com>
wrote:

Denis,

In case of incomplete baseline topology IgniteCache.rebalance() will do
nothing, because this event doesn't trigger partitions exchange or
affinity
change, so states of existing partitions are hold.

2018-04-11 22:27 GMT+03:00 Valentin Kulichenko <
valentin.kuliche...@gmail.com>:

Denis,

In my understanding, in this case you should remove node from BLT and
that
will trigger the rebalancing, no?

-Val

On Wed, Apr 11, 2018 at 12:23 PM, Denis Magda <dma...@gridgain.com>
wrote:
Igniters,

As we know the rebalancing doesn't happen if one of the nodes goes
down,
thus, shrinking the baseline topology. It complies with our
assumption
that
the node should be recovered soon and there is no need to waste
CPU/memory/networking resources of the cluster shifting the data
around.
However, there are always edge cases. I was reasonably asked how to
trigger
the rebalancing within the baseline topology manually or on timeout
if:
    - It's not expected that the failed node would be resurrected in
the
    nearest time and
    - It's not likely that that node will be replaced by the other
one.
The question. If I call IgniteCache.rebalance() or configure
CacheConfiguration.rebalanceTimeout will the rebalancing be fired
within
the baseline topology?

--
Denis



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