Do I need a private heartbeat network?

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Do I need a private heartbeat network?

Duran

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Points: 13259
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September 6, 2010 at 10:19 am

#226537

Hello I have read on several sites and in several respected books that I need to create a private network for the cluster heartbeat and have prepared to do so. However, I have come across this KB article that in one section says that I do not. The site is for windows 2003, but I am referring to the Windows 2008 reference that says a private heartbeat on a Win2k8 cluster will cause problems, I will be using Windows 2008.
So do I require one or not? Its confusing.
Regards,
D

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WayneS SSC Guru Points: 95460 More actions · Answer 1

Everything that I've read about clustering says that the private heartbeat should be on it's own network gear, separate subnet, etc. Essentially, try to keep it off of the main network - it produces a lot of traffic going back and forth between the nodes, and can be disruptive to the main network. And if IT gets slowed down, you can end up with nodes failing over - not good for your uptime requirements.

Wayne
Microsoft Certified Master: SQL Server 2008
Author - SQL Server T-SQL Recipes

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WayneS SSC Guru Points: 95460 More actions · Answer 2

Also, if you have a two-node cluster with the nodes really close together, you can use a network cross-over cable.

Wayne
Microsoft Certified Master: SQL Server 2008
Author - SQL Server T-SQL Recipes

If you can't explain to another person how the code that you're copying from the internet works, then DON'T USE IT on a production system! After all, you will be the one supporting it!

Links:
For better assistance in answering your questions
Performance Problems
Common date/time routines
Understanding and Using APPLY Part 1 & Part 2

Duran SSChampion Points: 13259 More actions · Answer 3

Hi Wayne,

Thanks for getting back, I think you are right and a heartbeat network is required. I was thinking of going with the Crossover cable solution (the servers are right next to each other), but was told 2 ports on a vlan was better, though you raise a good point in regards to the network speed.

Regards,

D.

mark.pleasance SSCrazy Points: 2070 More actions · Answer 4

Hi Duran,

You do need a dedicated network for the heartbeat.

(Do not setup a heartbeat connection through any shared network switch.)

A direct cable connection between two network adapters is considered a "network".

There is nothing more stable than a single piece of copper wire between two network adapters.

The only reason to use a switch for the heartbeat is if there a large physical distance between the servers.

It doesn't always "have to" be a cross over cable - most modern adapters are auto sensing and will automatically switch over.

(but a cross over cable ensures the connection and most people understand that connection type.) ;0)

Reason:

The heartbeat connection is time sensitive . . .

If the heartbeat takes too long (i.e. congestion within the switch fabric) the cluster will attempt to fail over to the secondary node.

It uses the heartbeat to perform that fail over action - and that will fail because the switch is congested.

Also:

Add in the heartbeat IP for the alternate server into the hosts file.

i.e.

Server1 host file entry . . .

192.168.0.2 Server2

Server2 host file entry . . .

192.168.0.1 Server1

You don't want backend communications between server1 & server2 to go through the primary service IP.

(which may occur if using DNS resolution.)

M

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Mark

Steve Jones - SSC Editor SSC Guru Points: 736212 More actions · Answer 5

I've seen both. I like the crossover cable since it's easy to setup and less to break.

Duran SSChampion Points: 13259 More actions · Answer 6

Hello,

Thanks for getting back everyone, most appreciated. I'm defo going for the cross over cable, thanks for the host entry tip, I was just going to leave off any DNS entries for the heartbeat NICs but presumably this is better.

Thanks again,

D.

Perry Whittle SSC Guru Points: 234013 More actions · Answer 7

Typically, (especially if you had more than 2 cluster nodes), you would use an isolated switch which only had the heartbeat traffic from the cluster nodes passing through it. You could also use VLANs on shared switch but i personally wouldn't!

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

MysteryJimbo SSC-Insane Points: 24203 More actions · Answer 8

Windows 2008 no longer requires a dedicated network for a heartbeat. It still has a heartbeat, but this can be configured to use a single or dedicated network interface.

http://support.microsoft.com/kb/258750

Note The information in this article does not apply to Windows Server 2008 or Windows Server 2008 R2 failover clusters. Implementing these recommendations on these versions of failover clustering can cause adverse behavior. Windows Server 2008 and Windows Server 2008 R2 failover clusters do not have to have a private heartbeat network and the networking settings in this article are not needed and may cause unwanted behavior.