November 27, 2007 at 10:52 am
Hi, need some advice or benefit of your experience.....
I have an app that truncates the log as part of one of its processes(!) so forced away from log shipping to mirroring as HA solution. I am on standard edition and do not have a server to act as a witness so the mode is high protection (FULL synchronisation with no witness)
my question is what happens to the primary if the mirror fails? I am getting conflicting info from my research. As there will not be a quorum will the primary also be unavailable for user connections if the mirror fails in this scenario?
cheers
george
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November 27, 2007 at 11:08 am
You can use SQLExpress as a witness. I'd set an instance of that on another server and configure that.
November 28, 2007 at 9:31 pm
The principal will continue to accept connections and process transactions if the mirror is down. The transactions will be queued in the principal's transaction log until communication with the mirror is re-established, whereupon the databases will get busy resynchronizing.
So you will need to keep an eye on your transaction log and ensure you have disk space enough to cope with any [long] outages that may occur. Note - transaction log backups will continue but they will not truncate the log. If you are going to run out of disk space for the log, you will need to remove mirroring and set it up again later.
MARCUS. Why dost thou laugh? It fits not with this hour.
TITUS. Why, I have not another tear to shed;
--Titus Andronicus, William Shakespeare
November 29, 2007 at 3:24 am
Scott and steve, thanks for the replies.
Reassuring to know it will keep going. This must mean that the documents are referring to the principal not accepting connections if you also have a witness in FULL mode and the mirror and witness are lost at the same time. An argument AGAINST having a witness I guess.
For my scenario I think I will avoid the use of the witness as the server is on a regular reboot schedule and I don't want the database failing over every time its rebooted, also I am just replacing log-shipping becuse of the log truncation so immediate failover is not required.
many thanks
george
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