August 30, 2011 at 3:26 am
Hi
I have a slow perfromance issue on one of my Production SQL Instances. The only thing that I can see that looks out of the ordinary is DBMIRROR_SEND being responsible for nearly 70% of the waits.
There does not seem to be much information on the inernet about this WAIT type apart from what is in Books online and one article that says that it can be a symtom of slow performance.
The instance mirrors 4 databases over the WAN to another site (including the Database with the performance issue). The mirroring is set up as synchronous on all Databases.
I was wondering if anyone else had experienced any problems in the past with this Wait type showing up top of the list?
Best Regards
Chris
August 30, 2011 at 3:49 am
Do you have any benchmark ping times over the WAN? It may be worth investigating the response time over the WAN to see how it compares to "normal operations". If the WAN is slow to respond then I guess that could give rise to this wait type.
August 30, 2011 at 4:09 am
Doesn't surprise me.
Synchronous mirroring to a different location means that a transaction can't be commited until the transaction has been received at the other end and it has signalled back that it's received. This could easily be the longest wait type, depending on the types of transactions, bandwidth and latency to the other site.
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