Question about add new nodes to ignite cluster.

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Justin Ji Justin Ji
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Question about add new nodes to ignite cluster.

I added 3 nodes to existing cluster, but not add them to topology, like
below:

Cluster state: active
Current topology version: 93

Baseline nodes:
    ConsistentID=0ded99c1-b19c-4ced-ba3a-06abe233c6c8, STATE=ONLINE
    ConsistentID=2c252722-a3c4-4f55-8d26-d216329fddbb, STATE=ONLINE
    ConsistentID=4ac614ce-4e4c-4bb4-a479-2b47f71138bf, STATE=ONLINE
--------------------------------------------------------------------------------
Number of baseline nodes: 3

Other nodes:
    ConsistentID=47ae0f2e-ae8e-468f-93a8-85fbb6ff8000
    ConsistentID=751da65f-99f7-488c-91d1-71d0365ffa4d
    ConsistentID=8a6b8281-50d8-4d0d-8933-0e51b67994a2
Number of other nodes: 3


We can see that the new nodes were not added to the topology. But what
puzzles me is that these three new nodes are starting to process data
requests, even though I didn't add them to the topology.

So what is the meaning of this topology? And what is the difference between
the nodes in and not in the topology?



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Mikael Mikael
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Re: Question about add new nodes to ignite cluster.

Hi!

You have it at the first paragraph in the documentation

"If Ignite persistence is enabled, Ignite enforces the baseline topology concept which represents a set of server nodes in the cluster that will persist data on disk."

The baseline topology is needed for persistence, if your nodes does not store data they do not need to be part of the topology, they can still do everything else.

Mikael

Den 2018-11-26 kl. 10:20, skrev Justin Ji:
I added 3 nodes to existing cluster, but not add them to topology, like
below:

Cluster state: active
Current topology version: 93

Baseline nodes:
    ConsistentID=0ded99c1-b19c-4ced-ba3a-06abe233c6c8, STATE=ONLINE
    ConsistentID=2c252722-a3c4-4f55-8d26-d216329fddbb, STATE=ONLINE
    ConsistentID=4ac614ce-4e4c-4bb4-a479-2b47f71138bf, STATE=ONLINE
--------------------------------------------------------------------------------
Number of baseline nodes: 3

Other nodes:
    ConsistentID=47ae0f2e-ae8e-468f-93a8-85fbb6ff8000
    ConsistentID=751da65f-99f7-488c-91d1-71d0365ffa4d
    ConsistentID=8a6b8281-50d8-4d0d-8933-0e51b67994a2
Number of other nodes: 3


We can see that the new nodes were not added to the topology. But what
puzzles me is that these three new nodes are starting to process data
requests, even though I didn't add them to the topology.

So what is the meaning of this topology? And what is the difference between
the nodes in and not in the topology?



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Justin Ji Justin Ji
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Re: Question about add new nodes to ignite cluster.

I understand, thank you very much.



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Justin Ji Justin Ji
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Re: Question about add new nodes to ignite cluster.

In reply to this post by Justin Ji
Another question:

How the client APIs get or put data to the rebalancing cluster(Async Mode)
when adding a new node to the cluster, from the old nodes or the new node?



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Stanislav Lukyanov Stanislav Lukyanov
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RE: Question about add new nodes to ignite cluster.

Well, in short - it does, don’t worry about it :)

 

Unfortunately I’m not aware of a proper design document explaining the process in detail.

But simply put, Ignite will wait for the new node to obtain all of the data it needs to store.

While that’s happening, the node doesn’t serve any requests.

When all data is transferred, Ignite will route the new requests to the new node, and start

removing the transferred data from the old nodes.

 

Stan

 

From: [hidden email]
Sent: 3 декабря 2018 г. 5:26
To: [hidden email]
Subject: Re: Question about add new nodes to ignite cluster.

 

Another question:

 

How the client APIs get or put data to the rebalancing cluster(Async Mode)

when adding a new node to the cluster, from the old nodes or the new node?

 

 

 

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Justin Ji Justin Ji
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RE: Question about add new nodes to ignite cluster.

Thank for your replies!

I agree with "the node doesn’t serve any requests."

But the documents write that:

Asynchronous rebalancing mode. Distributed caches will start immediately and
will load all necessary data from other available grid nodes in the
background.

under Rebalance Modes
https://apacheignite.readme.io/docs/rebalancing

what does "start immediately" mean? and what are the differences between
SYNC and ASYNC?

Looking forward to your reply~

Justin



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Stanislav Lukyanov Stanislav Lukyanov
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RE: Question about add new nodes to ignite cluster.

Here “cache start” is a rather internal wording.

It means “cache adapter machinery will be initialized”.

 

In case of ASYNC rebalancing the cache will first appear on the node as

existing but storing no data until it is rebalanced.

 

In practice, ASYNC rebalancing means that the node will start (Ignition.start() will return)

immediately, not waiting for the rebalance.

SYNC rebalancing means that the node will start only after all data was processed.

 

For example, say you have the code

    Ignite ignite = Ignition.start(cfg);

    System.out.println(Ignite.cache(“foo”).get(“k”));

where cache “foo” is a part of the configuration ‘cfg’.

Here, if “foo” has ASYNC rebalancing the value will be printed immediately.

If “foo” has SYNC rebalancing the value will be printed only after the rebalancing has completed.

 

Stan

 

From: [hidden email]
Sent: 22 декабря 2018 г. 13:24
To: [hidden email]
Subject: RE: Question about add new nodes to ignite cluster.

 

Thank for your replies!

 

I agree with "the node doesn’t serve any requests."

 

But the documents write that:

 

Asynchronous rebalancing mode. Distributed caches will start immediately and

will load all necessary data from other available grid nodes in the

background.

 

under Rebalance Modes

https://apacheignite.readme.io/docs/rebalancing

 

what does "start immediately" mean? and what are the differences between

SYNC and ASYNC?

 

Looking forward to your reply~

 

Justin

 

 

 

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