[Okta Webinar] Learn how to a build a cloud-first strategyRegister Now

x
?
Solved

No databases mounting while two servers switched off in a DAG with 3 server

Posted on 2012-09-08
7
Medium Priority
?
678 Views
Last Modified: 2012-09-09
HI,

I have 3 mbx servers. in that 2 are in office and another is in data center. All three are members of DAG. mbx1 and mbx2 are in office and mbx3 is in datacenter.

mbx2 server is failed due to hardware failure. But still mbx1 and mbx3 are working fine. But If I shutdown mbx3 server, all databases in mbx1 dismounts. Means out of three servers, if any 2 servers down means, the databases will not come up in third server. Is this the default behavior of exchange DAG and how to over come it?
0
Comment
Question by:pradeepns
  • 4
  • 3
7 Comments
 
LVL 3

Accepted Solution

by:
ExchangePandit earned 1500 total points
ID: 38379381
Yes, thats the default behaviour as the quorum will be lost.

Read more on DAG: http://technet.microsoft.com/en-us/library/dd979799.aspx

As far as how to over come this situation is concerned, you seem to have a stretched DAG across 2 data-centers with only 3 DAG members hence you need at least 2 members to be always up.

Solutions can be:

1. Add MBX4 in the Main Datacenter and Make one of the HUB servers (located in Main DataCenter) as your Witness Server as you will need a Witness when you have EVEN number of servers in a DAG.
2. Add MBX4 in the Secondary (DR) Datacenter and Make one of the HUB servers as your Witness Server (located in Main DataCenter) as you will need a Witness when you have EVEN number of servers in a DAG. Though have an alternate Witness server (ready to go) when you wish to do a data center switchover in case primary data center is completely down.

Another question for you is Do we have any active users on MBX3 at all? or is it just hosting passive copies of MBX1/2?

Regards
EP
0
 

Author Comment

by:pradeepns
ID: 38379405
No active users in mbx3. Only passive copy of all databases in mbx1/mbx2.

One more thing: If I add one more server mbx4 in datacenter or DR site, again minimum 2 servers should be up at a time right?


Thanks
0
 
LVL 3

Expert Comment

by:ExchangePandit
ID: 38379450
Formula is: n/2 + 1 where n is the number of DAG nodes.

In your case its n=4 (if you decide to put another MBX server)

Then you need: 4/2 + 1 = 3 servers up (don't forget the Witness Server i.e. the +1 here)

So lets say Out of 4 Mbx servers you have lost 2 MBX servers you still have quorum however if you have lost 3 MBX servers then you do loose the quorum.

If the DR site is hosting only passive copies then you have an Active/Passive model,
0
Creating Active Directory Users from a Text File

If your organization has a need to mass-create AD user accounts, watch this video to see how its done without the need for scripting or other unnecessary complexities.

 

Author Comment

by:pradeepns
ID: 38380322
Dear Exchangepandit,

Thanks for your valuable information. Can you pls explain what is active/passive model and how it is helpful in my existing situation?

regds
0
 
LVL 3

Expert Comment

by:ExchangePandit
ID: 38380454
Active Site= Active Users
Passive Site= No Active Users

Active Site= Active DB Copies
Passive Site= Passive DB Copies Only


:-)

Regards
EP
0
 

Author Comment

by:pradeepns
ID: 38380521
haha

thanks
Pradeep
0
 
LVL 3

Expert Comment

by:ExchangePandit
ID: 38380623
:-)
0

Featured Post

What does it mean to be "Always On"?

Is your cloud always on? With an Always On cloud you won't have to worry about downtime for maintenance or software application code updates, ensuring that your bottom line isn't affected.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

With so many activities to perform, Exchange administrators are always busy in organizations. If everything, including Exchange Servers, Outlook clients, and Office 365 accounts work without any issues, they can sit and relax. But unfortunately, it…
There can be many situations demanding the conversion of Outlook OST files to PST format and as such, there is no shortage of automated tools to perform this conversion. However, what makes Stellar OST to PST converter stand above the rest? Let us e…
This video demonstrates how to sync Microsoft Exchange Public Folders with smartphones using CodeTwo Exchange Sync and Exchange ActiveSync. To learn more about CodeTwo Exchange Sync and download the free trial, go to: http://www.codetwo.com/excha…
This video shows how to quickly and easily add an email signature for all users on Exchange 2016. The resulting signature is applied on a server level by Exchange Online. The email signature template has been downloaded from: www.mail-signatures…
Suggested Courses
Course of the Month19 days, 11 hours left to enroll

872 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question