Distributed architecture - help setting replica

[Ran Mizrachi]

Hi,

I'm running 2 VMs in Windows Azure cloud services.

I would like to have 2 master nodes that will act as a hot backup of each other (because Windows Azure can take down machine at any time for updates purposes...)

Therefore, i'm looking for configuration that will keep my nodes synced with all of my data all the time.

I'm using v2.0.13.

My current configuration is:

{

    "autoDeploy": true,

    "hotAlignment": true,

    "executionMode": "asynchronous",

    "readQuorum": 1,

    "writeQuorum": 2,

    "failureAvailableNodesLessQuorum": false,

    "readYourWrites": true,

    "clusters": {

        "internal": {

        },

        "index": {

        },

        "*": {

            "servers" : [ "<NEW_NODE>" ]

        }

    }

}

During my tests I took 1 machine off, inserted some records and brought the node back online.

I see that the nodes didn't sync. even though the hotAlignment is set to true - the new records was not copied to the other node.

What am I missing?

Thanks!

[alessand...@gmail.com]

Hi,

could help you look at this link

https://groups.google.com/forum/#!searchin/orient-database/HOT$20ALIGNAMENT$20STILL$20NOT/orient-database/5NCen4Zxfjs/5R1sVIrd7FAJ

Regards,

Alessandro

[Ran Mizrachi]

I understand.

so, following the answer in the link below, when the hot alignment is set to false what will happen in the scenario I mentioned? 

will it deploy the db once again once the node is online again?

Thanks!

[SavioL]

Hi Ran,
In case a node left the cluster hotAlignment the synchronization queue is left or not for hot alignment when the node will join the cluster again. It can be true or false

Regards,
Savio L.

[Ran Mizrachi]

Thank you for the quick reply but I didnt understand.

If the hot alignment set to false and then a node left the cluster and joined again - will the new data be copied to the new node?
Or will it be left in te same state as it was when it left te cluster?

Thanks

[SavioL]

I copied the text from the guide (http://orientdb.com/docs/2.0/orientdb.wiki/Distributed-Configuration.html) reading it I think if the parameter 'hot alignment' is true then the queue is left when the node back online is updated, and if the parameter is false tail is removed.

Regards,
Savio L.

[Ran Mizrachi]

What do you mean by tail is removed?

As for the docs, i saw that, the description for hot alignment is not clear at all.

How can you say that OrientDB is perfect For windows azure when you cant provide proper solution or at least workaround for cases like i specified before? Windows azure takes VMs down for updates about once a week...

[Ran Mizrachi]

Can you recommend a proper different approach to ensure uptime in Windows Azure?

[Adam Hunt]

While the docs refer to a 4 node cluster in the section titled Limitations running distributed I suspect that it would be advisable to run a three node cluster so that a majority can be reached when attempting to resolve inconsistencies.

I'd be greatly appreciative if a Orient guru could speak to whether or not my assumption is correct.

Adam

[Colin]

Hi Adam, Ran:

As Adam mentioned, I'd run a 3-node cluster so a quorum can be reached.

Also, keep hotAlignment set to false for now.

We're improving the incremental synchronization process in an upcoming release.

Thanks,

-Colin

Orient Technologies

The Company behind OrientDB