April 1, 2010 at 8:57 am
Hello,
I am trying to understand how witness server works.
I have 2 physical servers (A and B) that are needed to be in a database mirroring setup. Can I use a virtual machine to have a witness server.
But have few questions on how this setup works.
Virtual Machine and Physical server A resides on one location and Server B resides on remote site.
if Primary locations for some reason is down how does Witness server work? does the witness server go down too? if so how will the server B become active then?
Your help is very much appreciated.
Thank you.
April 1, 2010 at 2:07 pm
The witness can be any edition of SQL on any machine with network connectivity.
I will assume that you are referring to synchronous mirroring (high safety). If the primary site is unavailable then mirroring will effectively be suspended - neither the principal or the witness can see the mirror. You can manually force a failover if necessary (at a risk of data loss). Ideally the witness would be in a third location.
April 1, 2010 at 2:31 pm
Hi,
Thank you for the clarifying. we are setting up asynchronous with possibility for High Availability.
my other question is that can i install the witness server in a virtual environment and have it monitor principal server and secondary server?
is it possible to have a witness server in virtual environment?
April 1, 2010 at 4:40 pm
Although a witness can be used for asynchronous, there is no point as the databases won't be in sync and a failover would almost guarantee data loss. It also could cause bigger problems if you lose connectivity to the witness and the mirror then the primary will go offline.
Regarding using a virtual, it makes no difference - as long as the principal and mirror can connect to it then it is viable. It's not used for monitoring per se (it acts to form a quorum so that failovers can be controlled), there is a separate database mirroring monitor for that. BOL has lots of information on how to configure it and set up alerts to notify you of certain events.
Viewing 4 posts - 1 through 3 (of 3 total)
You must be logged in to reply to this topic. Login to reply