January 8, 2014 at 8:06 am
Hi,
We have configured DBmirroring for our production databases in highsafety mode with automatic failover. Our applications are coded in ADO.net and when failover is triggered either as manually or automatic few websites are not functioning as expected- as few videos are not palying and few searches are not working. Other websites are functioning as expected when failover is triggered to mirror DB's.
So how can we troubleshoot this kind of scenario- is this something we have to look into web.config file Connection string with Failover partner details.
Or is this related to application Connection Pooling?
I want to know the starting point from where i should start looking to resolve this issue.
January 9, 2014 at 2:03 am
Seeing as the mirror is an exact duplicate of the primary database, I can only assume at first look that your conenction strings are a bit awry.
It may be an idea to check the following:
1. Are the connection strings for each server dependent on the primary configured to use the failover server?
2. Does your failover server have access to any and all files stored externally to the database?
3. Have you copied the required logins and their SIDs from the primary to the mirror so that access remains unhindered?
Just the few points to be getting started with.....
Regards,
Kev
January 9, 2014 at 7:54 am
1. Are the connection strings for each server dependent on the primary configured to use the failover server?
Yes each web application has its own Connection string mentioned as below
Initial Catalog=Northwind;server=Primarysql;Failover Partner=MirrorSQL;User ID=webuser;Password=XXXXXX;Application Name=Website -happies
2. Does your failover server have access to any and all files stored externally to the database?-- i have to check with my webadmin on this.
3. Have you copied the required logins and their SIDs from the primary to the mirror so that access remains unhindered?-- Yes all the logins are transfered to Mirror DB server.
January 9, 2014 at 8:01 am
Hi,
did the user use the same SID? If you use local sql-user, they must use the same SID.
First you can test, if you have orphaned user:
http://www.fileformat.info/tip/microsoft/sql_orphan_user.htm
I hope it will fix your problem.
kind regards,
andreas
January 9, 2014 at 9:13 am
All the websites work when we do manual failover- so i can confirm that there is no issue with logins or orphan users.
January 9, 2014 at 1:23 pm
andreas.kreuzberg (1/9/2014)
Hi,did the user use the same SID? If you use local sql-user, they must use the same SID.
First you can test, if you have orphaned user:
http://www.fileformat.info/tip/microsoft/sql_orphan_user.htm
I hope it will fix your problem.
kind regards,
andreas
Using a local SQL user would not have helped because the user that the mirroring will run under needs to be a domain user. The only problem that could occur is if the users SID between the two end-points is different. That, as far as the user for the mirroring is concerned, is the only critical point.
January 9, 2014 at 1:29 pm
muthyala_51 (1/9/2014)
All the websites work when we do manual failover- so i can confirm that there is no issue with logins or orphan users.
I don't want to sound pedantic but you don't perform a manual failover, ýou perform a manual switchover. A failover will only occur under a fault condition.
Because a switchover works and a failover doesn't, I would be more inclined to concentrate on your server configuration. I have a suspicion that maybe a NIC-Teaming problem exists and only a partial failover is happening.
January 13, 2014 at 10:17 pm
dns?
Why is it that people who can't take advice always insist on giving it? - James Bond, Casino Royale
January 14, 2014 at 7:57 am
dbassassin (1/13/2014)
dns?
I don't think so. DNS entries (or their use thereof) would not be affected by the admin performing a manual switchover or an automatic failover.
January 14, 2014 at 8:47 am
I was more thinking about areas of the code where DNS is being used. I've seen cases where older parts of a system were pointed to serverA instead of a mirror dns entry. So when a failover occurs to serverB, those older parts failed.
Why is it that people who can't take advice always insist on giving it? - James Bond, Casino Royale
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