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Colyn1337
Asked: 2014-10-15 11:32:41 +0800 CST

Get-Cluster cmdlet fails when using -Name param

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Summary

When I call Get-Cluster powershell returns the name of my cluster. For simplicity sake, lets call it Cluster1. If I call Get-Cluster -Name Cluster1 it fails with an error.

Error:

Get-Cluster : Check the spelling of the cluster name. Otherwise, there might be a problem with your network. Make sure
the cluster nodes are turned on and connected to the network or contact your network administrator.
    The RPC server is unavailable
At line:1 char:1
+ Get-Cluster -Name Cluster1
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : ConnectionError: (:) [Get-Cluster], ClusterCmdletException
    + FullyQualifiedErrorId : ClusterRpcConnection,Microsoft.FailoverClusters.PowerShell.GetClusterCommand

Detail

My first thought is that I'm using the cmdlet wrong or winrm isn't working (it is). I also thought that maybe there's a difference in the way it's called that's causing the failure. Following that logic I reviewed the following technet page on the cmdlet:

Research: http://technet.microsoft.com/en-US/library/hh847254(v=wps.630).aspx

Based on the writing there, I couldn't discern an obvious user error. So I've tried a few things to figure it out. First I thought maybe I'm just constantly screwing up the typing so I did this:

$Cluster = Get-Cluster
($cluster.Name -like "Cluster1")

The conditional returns True so I'm not a cluster f at typing. Next I tried the following:

Get-Cluster | Where-Object{$_.Name -like "Cluster1"}

Which of course returns the cluster object. So, what's going on here? What's different with Get-Cluster -Name "Cluster1"?

Edit

Version info from Powershell:

PSVersion                      4.0
WSManStackVersion              3.0
SerializationVersion           1.1.0.1
CLRVersion                     4.0.30319.34209
BuildVersion                   6.3.9600.17090
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0}
PSRemotingProtocolVersion      2.2
powershell

1 Answers

  1. Based on my observation of running Get-Cluster against a few of the clusters I have at work, it seemed to me that -Name uses name resolution, so if there's anything that causes a problem resolving names, it will fail even if the name you give it is the local machine.

    I tried it with cluster names and cluster service names as well as names of the individual nodes in the cluster.

    I also added an entry in my HOSTS file pointing a fake name to one of the clusters, and was able to successfully use that name with Get-Cluster.

    To me this strongly suggests that the use of -Name relies entirely on standard name resolution in the OS.

    The case where Get-Cluster without name would work whereas Get-Cluster -Name localhost (or the actual hostname of the current machine) would not work, suggests to me that without a name parameter, Get-Cluster attempts to communicate with the cluster service directly on the current machine, which would not require any name resolution.

    In addition to name resolution, I believe that an RPC connection is made to the destination server when using -Name (even if it's the local machine), so even if name resolution works, the RPC service actually being unavailable, or a firewall being on could actually block that connection and cause the error you saw.

    I was not able to test this, as I don't currently have a cluster in our test environment and I can't intentionally break name resolution or RPC on a production cluster!

    Unfortunately, I could not back up this hypothesis with any kind of authoritative source (I couldn't find a definitive description of this behavior).

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