Server 2008 failover cluster...force change of IP on failover

We have two 2008 server boxes with Hyper V loaded and virtual servers running
happily. We use a product called GeoCluster to replicate from on elocal disk
to another, allowing us to separate the two servers from a shared disk
resource.

With this configuration,we can run a cluster that is geographically
dispersed and has nodes in seperate subnets on our WAN. Where we run into a
problem is that virtual machines in the cluster do not change IP addresses
when they migrate from one host to another.

Writing a script to change the IP address and gateway address is fairly
trivial. Where I am stuck is how to trigger that script? Does 2008 failover
provide any way to call a routine only when failover occurs?

You could add a generic script resource to your Hyper-V Application Group.
This resource would be triggered any time the resource comes online.

Regards,
John

Visit my blog: http://msmvps.com/blogs/jtoner

"Jeff Strubberg" <> wrote in message
news:2058FB59-8929-43D5-B71E-...
> We have two 2008 server boxes with Hyper V loaded and virtual servers
> running
> happily. We use a product called GeoCluster to replicate from on elocal
> disk
> to another, allowing us to separate the two servers from a shared disk
> resource.
>
> With this configuration,we can run a cluster that is geographically
> dispersed and has nodes in seperate subnets on our WAN. Where we run into
> a
> problem is that virtual machines in the cluster do not change IP addresses
> when they migrate from one host to another.
>
> Writing a script to change the IP address and gateway address is fairly
> trivial. Where I am stuck is how to trigger that script? Does 2008
> failover
> provide any way to call a routine only when failover occurs?

Dave;
Not sure our applications would allow a roaming address. Also, wouldn't
that leave you waiting on a dns update after a failover before clients could
reconnect?



"daveberm" wrote:

> On Jul 29, 1:29 pm, Jeff Strubberg
> <JeffStrubb...@discussions.microsoft.com> wrote:
> > We have two 2008 server boxes with Hyper V loaded and virtual servers running
> > happily. We use a product called GeoCluster to replicate from on elocal disk
> > to another, allowing us to separate the two servers from a shared disk
> > resource.
> >
> > With this configuration,we can run a cluster that is geographically
> > dispersed and has nodes in seperate subnets on our WAN. Where we run into a
> > problem is that virtual machines in the cluster do not change IP addresses
> > when they migrate from one host to another.
> >
> > Writing a script to change the IP address and gateway address is fairly
> > trivial. Where I am stuck is how to trigger that script? Does 2008 failover
> > provide any way to call a routine only when failover occurs?
>
> Why not just us DHCP assigned IP addresses and create a reservation
> for each server?
>

John,

That resource would move with the machine, correct? Meaning it would assign
the wrong IP address half the time. I'm not sure that's a big problem, since
IT personnel would likely be present for the move back to primary hardware.

"John Toner [MVP]" wrote:

> You could add a generic script resource to your Hyper-V Application Group.
> This resource would be triggered any time the resource comes online.
>
> Regards,
> John
>
> Visit my blog: http://msmvps.com/blogs/jtoner
>
> "Jeff Strubberg" <> wrote in message
> news:2058FB59-8929-43D5-B71E-...
> > We have two 2008 server boxes with Hyper V loaded and virtual servers
> > running
> > happily. We use a product called GeoCluster to replicate from on elocal
> > disk
> > to another, allowing us to separate the two servers from a shared disk
> > resource.
> >
> > With this configuration,we can run a cluster that is geographically
> > dispersed and has nodes in seperate subnets on our WAN. Where we run into
> > a
> > problem is that virtual machines in the cluster do not change IP addresses
> > when they migrate from one host to another.
> >
> > Writing a script to change the IP address and gateway address is fairly
> > trivial. Where I am stuck is how to trigger that script? Does 2008
> > failover
> > provide any way to call a routine only when failover occurs?
>
>
>

The more I think about it, the better this solution seems. Are MAC addresses
in 2008 virtual machiens stable, or are they dynamically assigned? If I had
a stable MAC, I could set a reservation in each of the two cisco switches
involved, then leave the virtual machine in DHCP mode.

"daveberm" wrote:

> On Jul 29, 1:29 pm, Jeff Strubberg
> <JeffStrubb...@discussions.microsoft.com> wrote:
> > We have two 2008 server boxes with Hyper V loaded and virtual servers running
> > happily. We use a product called GeoCluster to replicate from on elocal disk
> > to another, allowing us to separate the two servers from a shared disk
> > resource.
> >
> > With this configuration,we can run a cluster that is geographically
> > dispersed and has nodes in seperate subnets on our WAN. Where we run into a
> > problem is that virtual machines in the cluster do not change IP addresses
> > when they migrate from one host to another.
> >
> > Writing a script to change the IP address and gateway address is fairly
> > trivial. Where I am stuck is how to trigger that script? Does 2008 failover
> > provide any way to call a routine only when failover occurs?
>
> Why not just us DHCP assigned IP addresses and create a reservation
> for each server?
>

"Jeff Strubberg" <> wrote in message
news:970D9F83-6D8A-4FD9-A66E-...
> Dave;
> Not sure our applications would allow a roaming address. Also, wouldn't
> that leave you waiting on a dns update after a failover before clients
> could
> reconnect?

Yes, and this is true for almost every multi-site type of failover. Clients
need to get the new IP and start using it, which requires low TTLs on the
host records.

--
Russ Kaufmann,
MVP, MCSE: Messaging and Security, MCT, MCITP, MCTS and other stuff

ClusterHelp.com, a Microsoft Certified Gold Partner
Web http://www.clusterhelp.com
Blog http://msmvps.com/clusterhelp

"Jeff Strubberg" <> wrote in message
news:EF676189-B50D-46EC-A678-...
> The more I think about it, the better this solution seems. Are MAC
> addresses
> in 2008 virtual machiens stable, or are they dynamically assigned?

MAC addresses are based on the MAC address of the physical NIC being used.


--
Russ Kaufmann,
MVP, MCSE: Messaging and Security, MCT, MCITP, MCTS and other stuff

ClusterHelp.com, a Microsoft Certified Gold Partner
Web http://www.clusterhelp.com
Blog http://msmvps.com/clusterhelp

"Russ Kaufmann" <> wrote in message
news:C0666F41-0347-4627-905E-...
> "Jeff Strubberg" <> wrote in
> message news:970D9F83-6D8A-4FD9-A66E-...
>> Dave;
>> Not sure our applications would allow a roaming address. Also, wouldn't
>> that leave you waiting on a dns update after a failover before clients
>> could
>> reconnect?
>
> Yes, and this is true for almost every multi-site type of failover.
> Clients need to get the new IP and start using it, which requires low TTLs
> on the host records.

Augh... Back to your question...

If you use DHCP with reservations in each location, then the MAC address of
the VM will indeed be stable and can be used in each location.

--
Russ Kaufmann,
MVP, MCSE: Messaging and Security, MCT, MCITP, MCTS and other stuff

ClusterHelp.com, a Microsoft Certified Gold Partner
Web http://www.clusterhelp.com
Blog http://msmvps.com/clusterhelp

I agree, a virtual machine that could handle geographic dispersion over a
layer 3 network would be quite an enhancement. As for clients picking up the
new IP, this box runs a single app. I can change the client side icons to
call a dns refresh, then the application. That should cut changeover down to
just how long it takes for the virtual machine to report the IP change.

Thanks Dave, Russ. This looks like a much better solution than me trying to
graft a layer two link between two layer three sites.

"daveberm" wrote:

> On Jul 30, 5:27 pm, Jeff Strubberg
> <JeffStrubb...@discussions.microsoft.com> wrote:
> > The more I think about it, the better this solution seems. Are MAC addresses
> > in 2008 virtual machiens stable, or are they dynamically assigned? If I had
> > a stable MAC, I could set a reservation in each of the two cisco switches
> > involved, then leave the virtual machine in DHCP mode.
> >
> >
> >
> > "daveberm" wrote:
> > > On Jul 29, 1:29 pm, Jeff Strubberg
> > > <JeffStrubb...@discussions.microsoft.com> wrote:
> > > > We have two 2008 server boxes with Hyper V loaded and virtual servers running
> > > > happily. We use a product called GeoCluster to replicate from on elocal disk
> > > > to another, allowing us to separate the two servers from a shared disk
> > > > resource.
> >
> > > > With this configuration,we can run a cluster that is geographically
> > > > dispersed and has nodes in seperate subnets on our WAN. Where we run into a
> > > > problem is that virtual machines in the cluster do not change IP addresses
> > > > when they migrate from one host to another.
> >
> > > > Writing a script to change the IP address and gateway address is fairly
> > > > trivial. Where I am stuck is how to trigger that script? Does 2008 failover
> > > > provide any way to call a routine only when failover occurs?
> >
> > > Why not just us DHCP assigned IP addresses and create a reservation
> > > for each server?- Hide quoted text -
> >
> > - Show quoted text -
>
> As far as I know and in my experience the MAC address is stable once
> the VM is created. However, you always can change the MAC to be
> static as part of the configuration just to be sure. Regardless of
> how you change the IP address, you will have to deal with clients
> caching the old IP address. I suggest you set the TTL of the A record
> of your server to 5 minutes to help with that issue. Of course you
> will have to deal with AD replication as well, so depending upon your
> AD topology, it could be a while before all of your clients get the
> new IP address.
>
> Would you be interested in a cluster resource that would automatically
> fix the IP address of a VM after switchover and force DNS to replicate
> the change throughout the AD forest? Sounds like a great enhancement
> to the Virtual Machine resource or for a 3rd party developer.
>

Yes, the resource would move with the machine. You would need to develop the
script so that it checks the owning node and then assigns the proper
address.

Regards,
John

Visit my blog: http://msmvps.com/blogs/jtoner

"Jeff Strubberg" <> wrote in message
news:533B9522-E2DA-4E91-B581-...
> John,
>
> That resource would move with the machine, correct? Meaning it would
> assign
> the wrong IP address half the time. I'm not sure that's a big problem,
> since
> IT personnel would likely be present for the move back to primary
> hardware.
>
> "John Toner [MVP]" wrote:
>
>> You could add a generic script resource to your Hyper-V Application
>> Group.
>> This resource would be triggered any time the resource comes online.
>>
>> Regards,
>> John
>>
>> Visit my blog: http://msmvps.com/blogs/jtoner
>>
>> "Jeff Strubberg" <> wrote in
>> message
>> news:2058FB59-8929-43D5-B71E-...
>> > We have two 2008 server boxes with Hyper V loaded and virtual servers
>> > running
>> > happily. We use a product called GeoCluster to replicate from on
>> > elocal
>> > disk
>> > to another, allowing us to separate the two servers from a shared disk
>> > resource.
>> >
>> > With this configuration,we can run a cluster that is geographically
>> > dispersed and has nodes in seperate subnets on our WAN. Where we run
>> > into
>> > a
>> > problem is that virtual machines in the cluster do not change IP
>> > addresses
>> > when they migrate from one host to another.
>> >
>> > Writing a script to change the IP address and gateway address is fairly
>> > trivial. Where I am stuck is how to trigger that script? Does 2008
>> > failover
>> > provide any way to call a routine only when failover occurs?
>>
>>
>>