July 13, 2012 at 2:47 am
Hi all,
I have mirroring setup in synchronous mode with witness for automatic failover.
All this is working fine on SQL2008 R2 Enterprise.
I am planning some maintenance on the network which will make the principal "isolated" for a short period of time. The principal will lose connection to the partner (mirror) and the witness while these network changes are taking place.
To stop the database going offline, I am considering temporarily changing the mirroring setup from synchronous to asynchronous and also removing the witness. Then when the database "isolated" it won't go offline and the users will still be able to use the application which connects to the database.
Once the network changes are complete, I was then going to change the mode of operation back to synchronous with witness.
Anyone see any issues with doing this? When changing mirroring modes and removing / adding witnesses, does the principal db go offline whilst these changes are being applied, or is this a safe operation to carryout whilst the production system is in use?
Thanks
July 13, 2012 at 6:38 am
Not applicable. Reverting the suggestion.
July 13, 2012 at 8:57 am
Anyone?
July 13, 2012 at 8:59 am
You don't really need to change the operating mode, just remove the witness. When the principal becomes disconnected, it will transition to asynchronous automatically and then back to synchronous when it is able to. But you can change the operating mode if you want. Tehre's no issues with making wither of those changes in production.
July 13, 2012 at 9:03 am
Thanks Robert, much appreciated...
July 13, 2012 at 9:05 am
Shot in the dark here since you haven't really provided enough information regarding the environment to make a better answer.
I am assuming that the principal server will still be accessible by the application, just that it won't see the mirror or witness servers. Based on that, I would simply remove the witness from the mirror setup. You can leave the mirror in syncronous mode with out the witness and the principal database will continue to serve the application when it loses connection with the mirror.
Once the network connection between the principal and mirror comes back, they will resync and you can reestablish the witness server.
July 13, 2012 at 9:29 am
rdavies 35008 (7/13/2012)
Thanks Robert, much appreciated...
You're welcome.
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