Alternative file witness server in the same DC Exchange 2013 DAG

Hi Experts ,

Before the question below are  My configuration :-

I have exchange 2013 in DAG, Two mbx servers and Two cas servers running on  Two  Hyper-v host server running on windows server 2012 .

1. Host 1 server has MBX server 1 & CAS server 1 on hyper-v
2. Host 2 server has MBX server 2 & CAS Server 2 on Hyper-v
3.File witness server is running on CAS Server 1.
4. Fail over cluster type "Node and fileshare Majority"
5. Failover cluster members "Mbx1 ,Mbx2 & Cas1"

Is it required to configure alternative file witness server on same data-center.? The reason been ,recently I had to shutdown  host server 1 & 2 (Each servers one at a time) for a hardware maintenance .But when i took the host server 1 offline My all the 7 databases got dismounted whereas when i took the server Host 2 offline databases were running just fine , i didn't have any issue.

I assume DBs were dismounted because ,filewitness server and fail over member (MBX1) were offline out of 3 members participating on fail over cluster .

Please enlighten me on below doubts :-

A. What are the best practice to consider to avoid such a scenario?
B. How can i change File Witness Server  if existing File witness Server crashes ?
C. How can i move file winess server from CAS1 to CAS2 without downtime?
D. or Do i really need an alternative FWS ? if so , what are the steps to create ?

Thank you in advance for your support,

PS:-  All the exchange servers are running on Microsoft windows server 2012 .

Best Regards,
Sharaf.
LVL 1
Sharaf KEXchange 2013 admin & Network AdminAsked:
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timgreen7077Exchange EngineerCommented:
The reason the DBs got dismounted is because quorum was lost. It was lost when you rebooted CAS1 which is your witness server.
You can add an alternate witness server to help with that, by adding it on the other CAS server or a separate server that's not even an Exchange server at all. It doesn't have to be in the same datacenter, it just needs to be a server that's in the same AD Forest. The site doesn't matter as long as Exchange can access ping it. The easiest thing to do is not to change or move the Primary witness but to just add the Alternate Witness, so determine what server you want to add the alternate witness to and follow the same steps you followed when you setup the primary witness.

Notes:
Witness can't be added to DAG nodes, so don't add to your mailbox servers.
You can add the alternate witness to CAS 2, or any server you choose.
Datacenter and site doesn't matter, just same AD Forest
Be sure not to reboot the servers with the primary and alternate witness simultaneously.
Setup alternate witness the same way you setup the primary.
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MaheshArchitectCommented:
By only taking down witness server DAG cannot go down since dag nodes are still alive and have node majority (51%+) votes
Your DAG gone down because your witness server and one DAG member gone down same time
Alternate witness server cannot provide you automatic fail over incase primary witness server goes down
You need alternate witness server for datacenter switch over
You should not have two witness servers in primary data center
https://social.technet.microsoft.com/Forums/en-US/59fa1378-250a-422f-ad36-858eb70fab92/role-of-alternate-witness-server?forum=exchange2010
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Sharaf KEXchange 2013 admin & Network AdminAuthor Commented:
@Mahesh ::- i got the point. so what can i do if i want to shutdown host 1 server without getting databases dismounted??(where my fws & Mbx1 server s reside)???
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timgreen7077Exchange EngineerCommented:
Mahesh is correct. you can move the witness to a different server all together.
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MaheshArchitectCommented:
Ideally you should isolate witness server and mailbox server role
You can put file share witness on another member server , may be on another virtual server on another host / existing server
This will remove dependency
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timgreen7077Exchange EngineerCommented:
See the link for assistance with moving witness server. I wouldn't suggest putting on CAS. Put on a different server.

https://blogs.technet.microsoft.com/karthikm/2016/09/28/change-the-file-share-witness-on-exchange-server/
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MaheshArchitectCommented:
And there is no downtime required to change witness server
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Sharaf KEXchange 2013 admin & Network AdminAuthor Commented:
what if my FWS is already down ??? can i move FWS to new location by below comment ???

Set-DatabaseAvailabilitygroup -Identity <DAGNAME> -WitnessDirectory <C:\FSW_DIR_DAG1> -WitnessServer <Server FQDN>
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MaheshArchitectCommented:
yes, you can.
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timgreen7077Exchange EngineerCommented:
Yes that is correct
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MaheshArchitectCommented:
Answer provided
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