October 25, 2010 at 12:18 pm
I'm considering going from a 2-node SQL2k8 cluster to a 3-node environment. My current cluster is active-passive; I may go to active-active-passive.
I'm currently running Win2k8 std, and SQL2k8 std; will I need to upgrade to enterprise for either?
Can I add a new a new W2k8 server, configure clustering & then simply add the new node via the SQL install process? Will this in any way cause harm to my existing cluster?
If I have to upgrade to SQL Enterprise, can I perform an upgrade on an existing (passive) node?
Thanks in advance.
October 27, 2010 at 6:25 am
BigSam (10/25/2010)
I may go to active-active-passive.
This is a misconception, the cluster is either active\passive or active\active!
BigSam (10/25/2010)
I'm currently running Win2k8 std, and SQL2k8 std; will I need to upgrade to enterprise for either?
Hmm, Windows 2008 Std does not have failover clustering as an available option only NLB as far as I am aware
BigSam (10/25/2010)
Can I add a new a new W2k8 server, configure clustering & then simply add the new node via the SQL install process? Will this in any way cause harm to my existing cluster?.
You will need SQL Server Ent to support clustered instances on more than 2 nodes
BigSam (10/25/2010)
If I have to upgrade to SQL Enterprise, can I perform an upgrade on an existing (passive) node?
You would need to upgrade the active instance so no, not from a passive node!
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October 27, 2010 at 11:02 am
I was hoping I could have 2 nodes active simultaneously. Sorta renders the prospect of 3 or more nodes less than efficient, unless all are active.
If all nodes are active, how does one apply SQL or Windows updates/patches?
October 27, 2010 at 11:29 am
BigSam (10/27/2010)
I was hoping I could have 2 nodes active simultaneously.
You can for diffrent instances, that is an active\active cluster.
BigSam (10/27/2010)
Sorta renders the prospect of 3 or more nodes less than efficient, unless all are active.If all nodes are active, how does one apply SQL or Windows updates/patches?
The passive nodes are patched first. Even though all 3 nodes are active with different instances they could be passive to a partner node! Do you understand how clustered instances work?
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"Ya can't make an omelette without breaking just a few eggs" 😉
October 27, 2010 at 1:47 pm
I know how a 2-node active/passive cluster works. I thought I knew how a 3-node cluster works until I started reading your responses. My assumption with a 3-node cluster is that I would have 2 nodes active & the 3rd in passive mode. The passive (3rd node) would be the failover node for either of the active nodes. The applications are unaware of which node they are connecting to, just that they are connecting to a virtual SQL server (the cluster). When there are multiple active nodes, they each must share information with their peers, so that queries on any node don't conflict with queries on the other active node(s).
October 27, 2010 at 8:10 pm
BigSam (10/27/2010)
I know how a 2-node active/passive cluster works. I thought I knew how a 3-node cluster works until I started reading your responses. My assumption with a 3-node cluster is that I would have 2 nodes active & the 3rd in passive mode.
yes, that is a valid configuration, equally all three nodes could be active servicing 3 separate sql server instances.
Bigsam
so that queries on any node don't conflict with queries on the other active node(s).
no, you are referring to load balancing, SQL server does not perform that!
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"Ya can't make an omelette without breaking just a few eggs" 😉
October 28, 2010 at 2:50 pm
Thanks, I understand better now. Can you explain what happens in a 2-node cluster that is active/active? Does each instance 'mark' a database as active on that server & then processes all queries for that database?
October 28, 2010 at 2:59 pm
BigSam (10/28/2010)
Thanks, I understand better now. Can you explain what happens in a 2-node cluster that is active/active? Does each instance 'mark' a database as active on that server & then processes all queries for that database?
Not to but into the conversation 😀
2-node active/active clusters simply have an SQL Server instance running on each node, therefore each node is "active". Within Cluster Admin the cluster group is usually configured for a preferred node to run on. So Srv1/Srv2 cluster has SQL1 and SQL2 instances. I configure SQL1's preferred active node to be Srv1 and SQL2 likes Srv2. If something goes wrong with say SQL1 instance it will failover to Srv2 and you would have both instances running on Srv2 until you fixed Srv1.
Shawn Melton
Twitter: @wsmelton
Blog: wsmelton.github.com
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October 28, 2010 at 3:05 pm
BigSam (10/28/2010)
Thanks, I understand better now. Can you explain what happens in a 2-node cluster that is active/active? Does each instance 'mark' a database as active on that server & then processes all queries for that database?
active\active and active\passive refer to the instance level not the database!!
Consider the following scenario;
Server nodes "NODE1" and "NODE2" are formed as Windows cluster "CLUSTER-01".
You deploy a new SQL Server failover cluster instance on "NODE1" by launching the installer and selecting the appropriate action. This instance uses the network name "CLUSTINST1" and the instance name "LIVE".
You then go to "NODE2" and launch setup and select the "Add a node to a failover cluster" option. Both nodes now have the instance "CLUSTINST1\LIVE" installed and the instance is currently running on "NODE1".
You now deploy a second new instance as above and this is titled "CLUSTINST2\DEV".
Both instances are running on "NODE1", this is an Active\Passive cluster as "NODE2" has no active resources running.
You go into Failover Cluster manager and failover the instance "CLUSTINST2\DEV" to "NODE2".
One instance is now active on "NODE1" and one on "NODE2", this is an Active\Active cluster as resources are now active on both nodes.
HTH
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"Ya can't make an omelette without breaking just a few eggs" 😉
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