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MQSeries.net Forum IndexClusteringHow to keep cluster queue sequence number in sync after a DR

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Anant.v
PostPosted: Thu May 17, 2018 7:16 am Post subject: How to keep cluster queue sequence number in sync after a DR Reply with quote

Apprentice

Joined: 26 Nov 2014
Posts: 40
Location: Malaysia

Hi All,

We are facing many cluster issues after a DR exercise, mainly due to the fact that the cluster queue sequence number does not remains the same after the failback to PROD from DR. Mostly some queue manager will have a higher sequence number compared to other copies maintained by the other cluster member queue managers.

Can anyone please suggest if a PROPER SAN replication can fix this ? Or is a cluster refresh needed no matter what type of replication is used.

I am trying to figure out if there is a way to avoid refresh cluster after a DR, and if the sequence numbers can be maintained the same by any means.


Thanks to you all, for always enlightening me with new ideas !!
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Vitor
PostPosted: Thu May 17, 2018 7:23 am Post subject: Re: How to keep cluster queue sequence number in sync after Reply with quote

Grand High Poobah

Joined: 11 Nov 2005
Posts: 25310
Location: Ohio, USA

Anant.v wrote:
Can anyone please suggest if a PROPER SAN replication can fix this


What kind of improper SAN replication are you currently using?

How are you failing over from Prod to DR and back again?
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Anant.v
PostPosted: Thu May 17, 2018 8:12 am Post subject: Reply with quote

Apprentice

Joined: 26 Nov 2014
Posts: 40
Location: Malaysia

The SAN replication was a true synchronization. i.e. to copy all QMGR related directories, so that the state of cluster be preserved. In short :

1. MQ is replicated to DR locality - synchronous disk array replication of logs and data (including configuration)

2. Stop MQ in PROD

3. Stop disk array replication

4. Start DR QMGR.


The main question I have is , is there a way to preserve the cluster state information.
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Vitor
PostPosted: Thu May 17, 2018 8:22 am Post subject: Reply with quote

Grand High Poobah

Joined: 11 Nov 2005
Posts: 25310
Location: Ohio, USA

Anant.v wrote:
The main question I have is , is there a way to preserve the cluster state information.


The way you're doing it. State is persisted by MQ on disc.

You're either missing a directory (unlikely as it works Prod -> DR) or the replication isn't working DR -> Prod for something.

Or some of the disc is not replicating as fast as you think it is.
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gbaddeley
PostPosted: Thu May 17, 2018 4:16 pm Post subject: Reply with quote

Padawan

Joined: 25 Mar 2003
Posts: 1898
Location: Melbourne, Australia

What do you mean by "cluster queue sequence number" ? What errors are you experiencing?
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mvic
PostPosted: Sun May 20, 2018 6:44 am Post subject: Re: How to keep cluster queue sequence number in sync after Reply with quote

Jedi

Joined: 09 Mar 2004
Posts: 2050

Anant.v wrote:
We are facing many cluster issues after a DR exercise, mainly due to the fact that the cluster queue sequence number does not remains the same after the failback to PROD from DR. Mostly some queue manager will have a higher sequence number compared to other copies maintained by the other cluster member queue managers.

I guess you are looking inside the amqrfdm outputs, to know this, as sequence numbers are not dumped anywhere else.
But it is normal, when you run REFRESH CLUSTER, for some/all sequence numbers within that qmgr to jump up to the current epoch time.
I assume you had ran REFRESH CLUSTER in DR during this exercise (this would again be normal).
If you had/have network connectivity from your DR site to your prod site, and the same qmgr names and/or CLUSRCVR channel names in DR and prod, then your prod site will get very confused.
Now you need to run REFRESH CLUSTER on all qmgrs in your prod site which had some "new" version of themselves brought up in DR.
Before doing that, ensure that nothing remains running in your DR site that might continue to try to re-insert itself into your prod cluster.
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