September 13, 2014 at 7:30 pm
When setting up mirroring with witness server, what exactly the role of a quorum?
Also, if you setup mirroring with witness server, if the DR(Mirror) and witness server goes down, does that also make the PROD goes down as well since it's all part of the same quorum?
I was in the impression, that if DR and Witness goes down, PROD still will be up and only downside is that mirroring will be disconnected and in suspended mode and the log will grow on the PROD side, however, I was reading about the setup with witness server, and I read something like PROD will have downtime as well.
If anyone had configured mirroring with witness and has experience, please share. Thanks.
Regards,
SQLisAwe5oMe.
September 13, 2014 at 10:19 pm
"The session loses quorum.
If all the server instances become disconnected from each other, the session is said to have lost quorum. As server instances reconnect to each other, they regain quorum with each other.
If the principal server reconnects with either of the other server instances, the database becomes available.
If the principal server remains disconnected, but the mirror and witness reconnect to each other, automatic failover cannot occur because data loss might occur. Therefore, the database remains unavailable, until the principal server rejoins the session.
When all three server instances have reconnected, full quorum is regained, and the session resumes its regular operation"
Can someone explain, what exactly it means?
Regards,
SQLisAwe5oMe.
September 18, 2014 at 3:10 am
SQLisAwE5OmE (9/13/2014)
When setting up mirroring with witness server, what exactly the role of a quorum?
Quorum is the process by which the current resource owner is logged within a set configuration. It's there to prevent a situation where more than 1 owner attempts to control a resource, in this case, a mirrored database.
SQLisAwE5OmE (9/13/2014)
Yes, if the witness and mirror disconnect from the principal it will go offline to protect the database.
SQLisAwE5OmE (9/13/2014)
I was in the impression, that if DR and Witness goes down, PROD still will be up and only downside is that mirroring will be disconnected and in suspended mode and the log will grow on the PROD side
Only if you don't have a witness, the database mirroring documentation is pretty clear about the ramifications of using a witness server. It has its benefits but also some restrictions
SQLisAwE5OmE (9/13/2014)
however, I was reading about the setup with witness server, and I read something like PROD will have downtime as well.
Yes, if the mirror and witness connections to the principal are lost, the principal runs exposed and goes offline.
-----------------------------------------------------------------------------------------------------------
"Ya can't make an omelette without breaking just a few eggs" 😉
September 18, 2014 at 9:39 am
Thanks Perry for clarifying, appreciated.
Regards,
SQLisAwe5oMe.
Viewing 4 posts - 1 through 3 (of 3 total)
You must be logged in to reply to this topic. Login to reply