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Unable to activate Exchange 2010 Passive copy in DAG mode

Dear Experts,

I have exchange 2010 server setup in "DAG" mode in my environment and I need to perform Disaster recovery test. My setup is as below. Please note that below setup issue apply the same for the same AD site Environment and and different AD site environment

I have

- Two Exchange members in DAG group = SVR01 and SVR02 ( in DAG mode, SVR01 is Active, SVR02 is passive copy )
- Two server  == SVR00 and SVR03 (  SVR03 is primary FSW server and SVR00 is alternate FSW server )

When I shutdown Active copy, email is still flowing as primary FSW server is up and running.

If I shutdown both FSW server and Active copy server, my passive copy DB will show as Disconnected and dismounted as well. I can't manually mount too. If I do I get error as attached.

My question is why it is not using Alternate file share witness server even though
I set Alternate file share witness server to use for DAG when Primary file share witness server down ? Both Exchange servers and FSW servers are in Exchange trusted sub system group.

What am I missing ? Could you please advise ?

Thanks in advance
BMT
DB-dismounted.JPG
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bominthu
Asked:
bominthu
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1 Solution
 
Exchange_GeekCommented:
Are you Is SVR01 and SVR02 in different sites?

If yes please enable DAC mode for Exchange, to know how-to refer to link

Also, at the time of switchover, is the copy queue length and replay queue length in good state?

Regards,
Exchange_Geek
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bominthuAuthor Commented:
I didn't enable DAC mode as some topic recommend not to go for DAC if we have only have two exchange servers.

 What I'm trying to know is is if it is not DAC mode, it won't use alternate file share witness in case DAG fail over?


I'm not sure what was the status about copy queue length as we won't also know what would be the status in case of Disaster too. But I check the MailboxDB status when I was unable to mount the passive copy and it was showing Healty status.

Regards
BMT
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Exchange_GeekCommented:
Give DAC a chance and hope that'll serve you're purpose.

Read the following blog about misconceptions about DAG and Alternate Witness Servers and overall everything about failovers.

http://blogs.technet.com/b/exchange/archive/2011/05/31/exchange-2010-high-availability-misconceptions-addressed.aspx

Regards,
Exchange_Geek
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bominthuAuthor Commented:
Thanks Exchange_Geek,

The Blog you post is interesting.

Does that mean Alternate Witness server is only for DAC mode ?
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Exchange_GeekCommented:
It helps in voting - definitely yes and DAC does ensure that no server end up with wrong status.

Regards,
Exchange_Geek
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bominthuAuthor Commented:
Hi Exchange_Geek,

Thanks for your suggestion. In my case, I have only two DAG members in different AD Sites hence I can't activate DAC mode.

So if my Active copy hosted server and primary Witness server fail, could you let me know how I can activate passive copy hosted server ?

Thanks a lot
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Exchange_GeekCommented:
DAC doesn't have a limitation w.r.t nodes.

Regards,
Exchange_Geek
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bominthuAuthor Commented:
Hi Exchange_Geek ,

Which one you mean w.r.t nodes ?

Can we enable DAC if we have only two Exchange members which are in different AD Site ?

This post mentioned http://www.howexchangeworks.com/2010/05/datacenter-activation-coordination-dac.html DAC shouldn't be enabled when only two members are there in different AD SIte ?
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Exchange_GeekCommented:
That link is for RTM not SP1

Regards,
Exchange_Geek
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bominthuAuthor Commented:
Hi Exchang_Geek,

Thanks for your comment. Looks like I have to turn on DAC which I'm not very sure what are advantages and disadvantages of DAC turned ON mode.

The things is we have branch offices and whatever changes I plan to make to Exchange organization, I need to explain to other business units why I want to make changes.

How about you advise me what is the solution if it is only two DAG members without DAC mode, if primary Exchange server and primary witness server goes down, what WOULD be my option that I can do to bring the passive copy hosted server UP ?

Even if enabling DAC mode is the best for Disaster plan, I'm just curious to know what WOULD be the steps I can do to bring passive copy hosted server UP.


Please advise ?

Thanks
BMT
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