Getting the most out of your SQL Server 2008 Cluster

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Getting the most out of your SQL Server 2008 Cluster

Mark.L.Jones

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May 26, 2011 at 12:07 am

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Comments posted to this topic are about the item Getting the most out of your SQL Server 2008 Cluster

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Perry Whittle SSC Guru Points: 234013 More actions · Answer 1

Just a couple of points

Firstly there is no such thing as an

Active\active\active\passive cluster.

A cluster is either active\active or active\passive.

Secondly for dev and uat clusters, virtual is the way to go. I have used virtualisation (VMWare server and ESX server) for creating clusters using MSCS and more recently Veritas Cluster Server. Although with the current version of VCS it is somewhat tricky and troublesome, MSCS responds well in a virtual environment. Also, many people on this forum find my "Creating a virtual SQL Server cluster" guide very useful

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"Ya can't make an omelette without breaking just a few eggs" 😉

Balance SSCrazy Points: 2636 More actions · Answer 2

Was the active an genuine UAT environment for end users? I've always been led to believe that UAT required normal license and developer could only be used for actual developer types.

Lorenzo DBA SSC Veteran Points: 273 More actions · Answer 3

I would agree that Virtualization is the answer and is cost effective for both the hardware and licensing perspective. If you licence the by ESX host instead of the VM's, it is cheaper. We have a (3) node cluster composed of (3) VM servers. Windows Server 2008 R2 64 bit Enterprise with SQL Server 2008 R2 64 bit Enterprise. It runs perfectly and we use it for UAT Testing. Virtualization also offers an added HA layer as well as having SAN snapshots taken of each volume. We are very happy with the Clustered Virutal Machines we have.

Lorenzo DBA SSC Veteran Points: 273 More actions · Answer 4

In addition we also installed (3) SQL Server Instances one on each node so the servers do not get wasted. We plan for capacity to make sure that if a failover is to occur that one node can handle the load by itself.

Jonathan Kehayias One Orange Chip Points: 26778 More actions · Answer 5

Perry Whittle (5/26/2011)
Firstly there is no such thing as an
Active\active\active\passive cluster.
A cluster is either active\active or active\passive.

I'm not sure why you'd say there is no such thing as an Active/Active/Active/Passive cluster. I've built a few of them in the last year. Standard Edition has a limitation of 2 nodes in a cluster, but Enterprise and Datacenter editions support as many cluster nodes as the OS allows.

Features Supported by the Editions of SQL Server 2008 R2

You can have 4 cluster nodes, and 3 instances of SQL installed on them, with three nodes owning a different SQL instance and your failover node in standby.

Perry Whittle SSC Guru Points: 234013 More actions · Answer 6

as i said, a cluster is either active\active or active\passive irrespective of the number of nodes.

The following article states

Microsoft Technet
Server clusters can take two forms: active/passive clusters and active/active clusters.In active/passive clustering, the cluster includes active nodes and passive nodes. The passive nodes are only used if an active node fails. In active/active clusters, all nodes are active. In the event of a failover, the remaining active node takes on the additional processing operations, which causes a reduction in the overall performance of the cluster. Active/passive cluster configurations are generally recommended over active/active configurations because they often increase performance, availability, and scalability.

The configuration mentioned in the posts above would normally be referred to as an N+1 which essentially is an Active\Passive cluster anyway

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"Ya can't make an omelette without breaking just a few eggs" 😉

Jonathan Kehayias One Orange Chip Points: 26778 More actions · Answer 7

And the following article refers to it as an Active/Active/Passive cluster:

Reviewing and Testing SQL Server Cluster Configuration for Failover Scenarios

You are trying to split hairs over symantics here that can confuse people that don't know enough about clustering. Multinode clusters, or N+1 clusters are commonly referred to by the setup as Active/Active/Passive, Active/Active/Active/Passive, etc by most people in the community. Your article is from 2003, mine is from a more recent version of the Books Online. It is possible that the terminology has changed slightly in the last 8 years to make it easier for people to understand the setup better.

Oscar Zamora SSCrazy Points: 2067 More actions · Answer 8

Correct me if I am wrong, but I see a combination of Enterprise Edition and Developer Edition binaries in Node 4. It seems that they can coexist with no problems. Is that accurate?

I do have MSDN licenses and might use them instead of Developer Edition Licenses. Wondering if the DLLs can coexist.

Paul Randal One Orange Chip Points: 29544 More actions · Answer 9

I would agree that describing a cluster as active/active/active/passive can be more descriptive than saying N-1, where N=4 - depending on the audience. Both terms are in use and neither is incorrect. Depends on what you're describing.

Quick poll of the system engineers at the client I'm onsite at today gives a mixture of answers. It also depends on how large N is. If N=8, no-one's going to say active/active/active/active/active/active/active/passive....

Just one more example of duplicate nomenclatures with people preferring one over another that serves to confues those who aren't experts.

Paul Randal
CEO, SQLskills.com: Check out SQLskills online training!
Blog:www.SQLskills.com/blogs/paul Twitter: @PaulRandal
SQL MVP, Microsoft RD, Contributing Editor of TechNet Magazine
Author of DBCC CHECKDB/repair (and other Storage Engine) code of SQL Server 2005

Perry Whittle SSC Guru Points: 234013 More actions · Answer 10

it doesn't however mention, Active\Active\Active\Passive.

Next time i build myself an 8 node cluster with 3 passive nodes it'll be an Active\Active\Active\Active\Active\Passive\Passive\Passive

i suppose.

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"Ya can't make an omelette without breaking just a few eggs" 😉

chrisfradenburg SSCrazy Eights Points: 9592 More actions · Answer 11

Thanks for the article. It's one I'll have to keep in my bag of tricks because it'll likely come in handy some day.

SQLHA SSC Veteran Points: 251 More actions · Answer 12

Actually, A/A and A/P are wrong terminology for SQL Server. I helped start that way back in the SQL Server 2000 days when I was still an employee of MS and wrote the SQL 2K failover clustering whitepaper.

The proper term is some variation of single instance failover cluster (or failover clustering instance) or multiple instance failover cluster. I've seen a variation with active in the name, I've seen where SQL Server is explicitly called out.

For SQL Server, A/P and A/A were holdovers from SQL Server 7.0 clustering where you literally could only have a maximum of two installs (and I'd rather try to block that ugliness out of my head). It makes no sense to say active/active/passive or a/a/a/a/a/p since that is probably not what it looks like. For example, you could have a three node cluster but have four instances running on two nodes. That isn't a/a/a/a/p.

When they introduced instancing in SQL Server 2000, we had talked about a name that made sense. My whitepaper was the first place to use the newer stuff and it's evolved a little over the years. Unfortunately, people are still clinging to A/P and A/A. Much like Windows clustering will always be referred to by some as MSCS. It is what it is.

Now you know ... the rest of the story.

So yes, I'm still a bit chuffed and annoyed people are using A/P and A/A. At this point it's like people spelling my name wrong (i.e. Alan, Allen). I try to ignore it but know that it is wrong terminology.

Also, N+1 comes from W2K Datacenter and you could do up to four nodes, boxes were smaller so having multiple instances were more of a challenge, and have a single dedicated failover node was a potential scenario. It evolved into N+i, where i is a number of dedicated failover nodes in the Windows failover cluster since it's easier now to have more than one dedicated failover node if you want. I believe the SQL 2K failover clustering wp was one of the first places to use that as well. That is proper use of N+i. I've never seen something like what Paul said with N-i or whatever.

Allan Hirt

PS - I won't shame anyone in a public talk if you use A/P or A/A. 🙂

PPS - I highly recommend if you want to see how complex a multiple instance topology can be, take a look at my whitepaper "Applying Updates to a Clustered Instance of SQL Server 2008 or SQL Server 2008 R2" which is linked from my blog post here[/url].

alen teplitsky SSC-Dedicated Points: 30014 More actions · Answer 13

Lorenzo DBA (5/26/2011)
I would agree that Virtualization is the answer and is cost effective for both the hardware and licensing perspective. If you licence the by ESX host instead of the VM's, it is cheaper. We have a (3) node cluster composed of (3) VM servers. Windows Server 2008 R2 64 bit Enterprise with SQL Server 2008 R2 64 bit Enterprise. It runs perfectly and we use it for UAT Testing. Virtualization also offers an added HA layer as well as having SAN snapshots taken of each volume. We are very happy with the Clustered Virutal Machines we have.

if you need it only for testing and don't care about some management features there is a free version of ESXi server you can download. i was running it until a few days ago when i switched to hyper-v

alen teplitsky SSC-Dedicated Points: 30014 More actions · Answer 14

we're in the process of going to windows 2008 r2 and sql 2008 r2 or denali. we put windows 2008 r2/sql 2005 on our QA/UAT servers for the application testing. the real production machines that are clustered were untouched until the cut over. we had some issues and tested clustering and SQL on them prior to the move but then we completely wiped them and reinstalled everything to have a clean slate for production.

virtualizing SQL is OK but for the most critical machines you will want things like dual gigabit NIC's and having a second box in case the OS or a windows update screws up. in the last 5 years we used to cry when we had to reinitialize replication on some important tables. in a few cases it would take 11-12 hours. these days we can run a snapshot on the same tables in 5-10 minutes in some cases. we we had these on vmware they would be competing for resources with other instances

our newest SQL boxes have 72GB of RAM in each one