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Clustered modems

Simon Dyson
Occasional Contributor

Clustered modems

Does Windows clustering support redundant modems?

I have an application where users dial into the server to pull out some data. If the cluster fails over I would like the users to be able to dial back in and connect to my application on the modem connected to the other server.

My thoughts were to have a modem in each server connected to a single wall phone socket and somehow configuring the cluster software to move the modem over as a resource on a failover. Any help would be appreciated.
Doug de Werd

Re: Clustered modems

Windows clustering does not specifically support "clustered modems". The core idea of an MSCS cluster is to switch ownership of the disks, which contain the applications and data. As such, basically the only thing that can fail over is something attached to the external shared SCSI bus, which pretty much excludes modems. anything that fails over must be defined with a Resource Type, and there is no Resource Type for modems.

That being said, I believe there are other technologies which could be used. I would look at something called a "modem pool" (I just checked this on Google and got a bunch of hits). You could use a modem pool to create availablity for the modems, and you could combine that with clustering for the application if you want. You just have to deal with them separately, as the modem failover can't be handled by the MSCS software.

I also checked Google with "clustered modem" and got some interesting stuff, like this:


Expert in ProLiant Clusters
Steven Clementi
Honored Contributor

Re: Clustered modems

If you can create an application, or have one created, or find one that enables the pickup on a modem... you can set up in the MSCS as a generic app that can failover. You would just need to set the modems default vaules to NOT answer unless this app is running.

Not sure if this is doable, but would definitely like to hear more if you find something.

Steven Clementi
HP Master ASE, Storage and Clustering
MCSE (NT 4.0, W2K, W2K3)
VCP (ESX2, Vi3, vSphere4, vSphere5)
NPP3 (Nutanix Platform Professional)