SQL Server Cluster Configuration

Last Post 26 Feb 2008 01:05 PM by bigelectricmac. 8 Replies.
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bigelectricmac
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22 Feb 2008 06:49 AM
We implemented a two node corporate SQL Server cluster about two years ago. We are wanting to add a third node to this cluster. However, our two nodes are dual 3GHz processors with hyper threading and 4 GB of RAM. The server team has spec'd out the new node and it is a dual quad-core box with 8GB of RAM. Essentially, we have two Dell 1855 blades, and the new node is a 1955.

Are we goinbg to run into problems if we try to cluster these machines? I would think so, but I need some sort of reference.

Thanks a lot,

Chris
SQLUSA
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22 Feb 2008 07:29 AM
What will be the configuration?

One 4GB CPU will be the passive for the new 8GB CPU?

The general wisdom is that you want to have symmetrical nodes, but then again money rules!

Kalman Toth - Database, Data Warehouse & Business Intelligence Architect
SQLUSA: http://www.sqlusa.com/order2005highperformance/ The Best SQL Server 2005 Training in the World!
bigelectricmac
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22 Feb 2008 09:21 AM
We currently run active/active on the two existing nodes. So the idea would be to add this new node and run two new instances on it (6 instances total).

Is this possible? If we do this, will it affect my min/max memory and CPU affinity settings within each SQL Server instance?

Can we run into issues simply because we are running on different hardware with potentially different drivers? ie failing over from a dual proc hyper threaded machine to a dual duad core proc machine or vice versa?

Chris G

bigelectricmac
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25 Feb 2008 12:34 PM
By "Same Hardware" do you mean that we cannot mix Dell 1855 servers with Dell 1955?

Thanks,

Chris
bigelectricmac
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26 Feb 2008 06:43 AM
They both use Intel Xeon processors. But the similarities end there.

The motherboards use different chipsets.
They have different NICs (Broadcomm vs Intel).
Front Side Bus is 800 MHz vs 1066MHz.
Memory runs at 667MHz vs 400MHz.

Does this sound like a bad match for clustering?
bigelectricmac
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26 Feb 2008 08:21 AM
Yes, I have taken those conditions into account when they added this node. I knew that I would probably not be able to fully utilize the new node because of what would happen in the event of a failover.

I am probably going to push to have all three nodes made identical. In the meantime though, should I expect to see issues when clustering these servers together? I would not consider this configuration to be reliabe. Is that a fair statement to make? Would anyone else run this configuration?
bigelectricmac
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26 Feb 2008 09:58 AM
The reason I am asking is because when I try to add that server as a third node, MSCS fails and the cluster comes down. Also, I am not able to add it as a failover node to two of my four instances.


You bring up another interesting point and maybe i have been configuring something wrong. I have been limiting the amount of RAM that SQL Server is using in order to guarantee that RAM would be available in case a failover occurs. for example, on the nodes with 8GB of RAM, i am limiting SQL Server to a maximum of 4GB. Should I not do this and let SQL Server continue to use RAM dynamically and just make adjustments in the event that a failover does actually occur?



bigelectricmac
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26 Feb 2008 01:05 PM
Ok. Thats the way I'm running right now. What are your thoughts on the PAE and 3GB switches?

bigelectricmac
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27 Feb 2008 06:11 AM
My mistake. I had the wrong numbers in that first post. It should have read that the two existing nodes have 8GB of RAM and the new node has 16GB. My apologies. I am currently using the /PAE switch on my existing two nodes. Have you ever run into a situation where using the /3GB switch starves the OS of memory resources and creates other problems?

I really appreciate all the input you have provided. Thank you very much for your help Gunnyk.
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