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DAG failover issues (again)

Posted on 2013-10-24
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Last Modified: 2013-11-09
Hi

Back to this one again, still unresolved after more testing. The issue is, if the databases failover to the DR exchange server for any reason, while the HQ server is still up, Outlook stops working.

To recap:

2 physical sites, each with a DC and configured as separate AD sites on different subnets.

Each site has a single Exchange 2010 server with ALL roles, and configured in a DAG.

HQ contains all users and the DR site is purely passive until such time as a failure.

Topology below:

HQ IP Range: 192.168.61.0/24
DR IP Range: 192.168.32.0/24

exch-hq - 192.168.61.40
exch-dr - 192.168.32.40

DAG Name: company-dag
DAG IP's: 192.168.61.45 & 192.168.32.45
Primary Witness: HQ Site
Alternate Witness: DR Site

Get-MailboxDatabase -Server exch-hq | fl name, rpc*

Name: DB01
RpcClientAccessServer: exch-hq.company.com

Name: DB02
RpcClientAccessServer: exch-hq.company.com

I think there a few misconfigurations in place here, from things I have read about.

Having dedicated CAS Array servers with NLB etc is NOT possible, so we are going down the DNS route which I know can work.

1. RpcClientAccessServer setting
2. DAC Mode
3. DatabaseCopyAutoActivationPolicy - does this need to be set?
4. How do you test permissions for Witness servers to be 100% they are working?
5. AllowCrossSiteRpcClientAccess - does this need to be set?

I'm thinking I should create a cas.company.com DNS entry with a low TTL, point it at exch-hq (192.168.61.40).

Then change the RpcClientAccessServer property to cas.company.com, manually changing the IP in DNS when failover occurs

But the other commands (and any I missed) - do these needs to be set?

Have I missed anything?
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Question by:bikerhong
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by:-MAS
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Please make sure your witness server is configured properly.
Try recreating the witness folder in DAG properties
Check this
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Expert Comment

by:Mahesh Sharma
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by:bikerhong
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Ok, I think I have this working to a satisfactory point.

I created a cas array object (which exists only in DNS)
I created a cas dns object with a TTL of 5 mins pointing to exch-hq
I assigned this cas object to a test database

Testing:

Test DB mounted on Exch-HQ with client at HQ, with Outlook profile reconfigured to look at cas dns record.

All OK.

Failed test db over to DR, Outlook comes up and says it needs to be restarted.

Restart Outlook, all OK.

Failed back, same thing happens.

This is "acceptable", I dont think we can get failover working seamlessly without some actual CAS servers?

If there is anything else to add to this please do so, we are still testing, if no replies in a few days I will select the most appropriate best answser.
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bikerhong earned 0 total points
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Update - setting AllowCrossSiteRpcClientAccess property allows outlook to failover without prompting for restart!
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by:bikerhong
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