XenServer 6: There Was an Error Connecting to the Server. The Service Did Not Reply Properly

GoombaWow, this is a really overly complicated error for such a simple problem to resolve. Allow me to give you some background.

I am currently building my first production ready (well non-production really) XenServer cluster and ran into this issue when attempting to add my second host into the cluster. I hit google and found out that this was actually just a dns issue.

A quick check on the /etc/resolv.conf on two of my nodes, shows nothing but the following line.

; generated by /etc/sysconfig/network-scripts/ifup-post

Well great, on a standard linux box I would have just added my name server and would have been half way to the bar, but judging by the contents of the resolv.conf I figured that I was supposed to add it another way.

Well after a bit of poking around in XenCenter I found this. Click on the hostname of the XenServer, then click on the "Networking" tab, from there click on "Configure…" below the "Management Interfaces" section as illustrated below. You will then be presented with a pop-up window where you can enter your nameservers.

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Once you have configured DNS properly you can then add the host to the cluster.

Note that you can also do this from the command line, however you have to go basically reconfigure your management interface.. ip, gateway, and everything that goes with it.

First run the command below

#xe pif-list host-name-label=xen01 management=true

Then using the UUID of the management interface, run the command below. Replace my IP addresses and uuid with yours.

#xe pif-reconfigure-ip mode=static IP=10.120.72.11 uuid=dc6b6651-6067-9a52-2011-6ba102da39e1 DNS=10.120.69.1 netmask=255.255.255.0 gateway=10.120.72.1

Seeing how fickle XenServer Clustering is regarding DNS, its probably not a bad idea to add /etc/host entries on your XenServer nodes for each server that will be in your cluster.  You never know when dns might go out to lunch and you don't want your HA cluster affected.

For future reference you can check all the configuration parameters of your management interface with the following commands.

First get the UUID of your management interface.

xe pif-list management=true host-name-label=xen01

Then check the configuration via the UUID.

xe pif-param-list uuid=f61b8d4d-67ec-e262-3e16-4348baaed076

And for example if you need to configure the DNS search domain, you can run the following.

xe pif-param set uuid=f61b8d4d-67ec-e262-3e16-4348baaed076 other-config:domain=MYDOMAIN

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How Not to Assign KVM IP Addresses Via Cisco UCS Manager

Boxing-gloveAfter a few hours poking around a newly deployed UCS cluster trying to get some basic profiles created and assigned. I realized that I had actually no idea how the KVM is actually supposed to work inside the UCS cluster. Which is funny as this was a subject that we touched on during my DCUDC class. Apparently we did not touch on it enough.

Anyway, before I get ahead of myself, lets review the gear in this cluster.

2 5108 chassis
7 B200 M2 blades with 2104 IOMs
2 6248s Fabric Interconnects

Now in my network all lights out management ips (ilos, ipmi, etc) are all on one particular vlan, which for the purpose of this post we will call VLAN 100. Non application related infrastructure equipment (servers, virtual hosts) are on another vlan, which we will call VLAN 200. So when the Fabric Interconnets were deployed, I gave them each an ip address on VLAN 200. And once UCS Manager was up and running, I created a KVM ip address pool of unused ip addresses on VLAN 100. Well guess what, this is wrong.

Routing for the KVM addresses is done through the management interfaces on the Fabric Interconects, so unless you are using vlan tagging, your KVM pool must be on the same vlan as the ip addresses assigned to your Fabric Interconnects.

But wait, why is this?

I thought that I could even assign private 192.168.x.x ip addreses to the KVMs as they were only supposed to be managed via the UCS Manager, but this also incorrect.

Navigate to one of your working KVM ip addresses in a web browser and you can access the KVM of the blade outside of UCS Manager. Nice, which is how I actually expected this to work. 

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Note that I find it rather dumb to have my KVM management ips and Fabric Interconnects on the same vlan as a rule, however since this is how its supposed to work I am going to have to let that one go.

Now, the fact that you can navigate to a specific KVM IP address via a web browser also makes the idea of using a pool of ip addresses silly. Would you not want to hard code the KVM ip address in the service profile so that you always know which server's console you are logging into? Dunno, I am still working on figuring that one out.