SQL Server Performance Forum – Threads Archive
Active/Active Cluster database access questionI currently have a Windows 2003, SQL Server 2000 SP3a Active/Passive cluster. My boss wants to have zero downtime for this system, and wants to buy another SQL license and convert this to an Active/Active cluster to accomplish this. I’m just not sure this will accomplish what he wants. I think he wants this because the application using the database does not automatically reconnect after a failover – someone has to manually restart all the services on all the servers when that happens. I know how to make the cluster Active/Active, but I don’t understand what will happen with the databases. Right now, because it is Active/Passive, all the databases are in one cluster group and all belong to V1/instance1. My understanding is that when I make node2 Passive/Active, it will have its own set of databases. I assume that we’d put a load balancer in front of the virtual servers. If we have copies of the same databases on both instances, how are we supposed to keep the databases in synch? I see a problem trying to use replication if they both failover to the same node. Maybe I’m just wrong about what happens to the database, but what I’m thinking is that unless both instances can use the same database, an Active/Active cluster won’t accomplish what he wants. Please help relieve my confusion!
Read this site and forum and you find a lot of info: http://www.sql-server-performance.com/clustering_intro1.asp
http://www.sql-server-performance.com/clustering_resources.asp Active/active is not about load balancing, it’s two seperate instances with its own disks and databases. Microsft clustering protects against hardware and/or application failure on one node. In that case the other node takes over the same sql instance while you can repair the other node. For applications to handle a failover they have to be coded to reconnect. This is by design: SQL Virtual Server client connections must be controlled by clients
http://support.microsoft.com/kb/q273673/ You could also look into replication or SQL 2005’s new features like database mirroring.
Thanks. This is what I understood. I think that Oracle RAC handles clustering the way he wants, so he just expected SQL Server Active/Active clustering to behave the same way. Before I shoot down his idea, I wanted someone to confirm what I thought. We are the first client this vendor has to even use Active/Passive clustering – they didn’t even know how to install it. I was interestd in SQL Server 2005’s database mirroring, but this vendor won’t even let me install SQL Server SP4, so SQL Server 2005 is out of the question for some time. You are correct – if the application was coded correctly …. I’m sure it is quite obvious how I feel about this vendor. I guess we’re just stuck right now, which is what I expected. Like I said – he decided all this on his own and I just found out by accident what he was planning to do. Thanks for all your help!