Forum Discussion
NimbostratusLoad balancing read only SQL 2008R2 servers
We have everything setup in the LTM and everything is working right. Traffic is getting balanced equally between our MS SQL server (read only). But the issue we are seeing happens when a server goes out for maintenance. We have a health monitor setup to query a DB and the LTM knows when the SQl server it down. But it seems the web servers connections to the SQL servers are keeping the connection alive.
Here is a copy of the error that is recieved: System.Data.SqlClient.SqlException: A transport-level error has occurred when sending the request to the server. (provider: TCP Provider,error: 0 - An existing connection was forcibly closed by the remote host.)
After this happens, the web servers then move over to the next available node.
the VIP is setup for performance layer 4, web servers are server 2003, and our SQL servers are server 2008R2 setup with n-path.
15 Replies
Tim_a_willis_92The models used in this instance is the BIG-IP Virtual Edition, there are 4 of them in active/active/active/standby
Here is screen shot of the dashboard from the LTM hosting the SQL:
And thank you for your help with this!
What_Lies_Bene1Cirrostratus
You're welcome and thanks for the picture. I don't see why sending the return traffic back would be an issue performance wise, things look pretty low and as it's a performance L4 VS it's going to add very little overhead (and very little extra latency). Of course, testing is always advised.
- What_Lies_Bene1
Hmmm, what model? What's the CPU and memory usage like? How many concurrent connections?
- Tim_a_willis_92
Our LTM is shared with many businesses within our company. And our hosting services within our company thought it might have too much of a load on LTM load balancing the SQL servers.
- What_Lies_Bene1
Well, I imagine that even if reselect works, the previous server still believes it has a valid connection to the client and that eventually times out and is reset. Do you know why you're using nPath?
- Tim_a_willis_92
So is it possible that the npath is keeping the connection alive then?
- What_Lies_Bene1
Only just noticed you're using nPath. As the LB is only involved once to make the initial load balancing decision surely whatever you set it'll fail as the F5 isn't acting as a proxy here.
- Tim_a_willis_92
We have tried that too already
- What_Lies_Bene1
So, how about changing Action on Service Down to Reject; won't that speed up the recovery, even if it's not transparent?
- Tim_a_willis_92
No irules in place for this VIP and the LTM is version BIG-IP 11.3.0 Build 3022.0 Hotfix HF3
- What_Lies_Bene1
Interesting. Would this apply? http://support.f5.com/kb/en-us/solutions/public/8000/100/sol8160.html
Any iRules in play?
Any authentication involved?
