Forcibly Remove a Host From XenCenter via CLI

PicklePD3Welcome back to another XenServer adventure. Today we are going to review the process of removing an orphaned XenServer host from XenCenter via the command line.

A few days ago one of my Xen hosts died due to an issue with the raid controller. In order to revive it I had to rebuild it, and add it back into the pool. However there was a problem; the original entry for this host in XenCenter appeared in red, which indicated that it was disconnected, and another entry for the same exact host with the same exact hostname appeared next to it in the host list for this particular cluster. I was unable to remove the orphaned host via XenCenter as there was no remove option.

I was in a pickle.

However I was able to find a solution.

First and formost it appears that there are actually two ways to do this; the first one being from the Windows command line where you are running Xencenter, or on the master node in the cluster.

This example is from the Windows CLI. Note that the UUID that is output to the command line is the UUID of the Host that is unreachable — the orphaned host.


C:\Program Files\Citrix\XenCenter>xe -s <Hostname_of_master> -u root -pw <root_password> pool-sync-database
You attempted an operation which involves a host which could not be contacted.
host: 560e233b-0e8b-4c2f-a641-cf1876630a6b (virt04.atlc1)

C:\Program Files\Citrix\XenCenter>xe -s <Hostname_of_master> -u root -pw <root_password> host-foget uuid=560e233b-0e8b-4c2f-a641-cf1876630a6b
WARNING: A host should only be forgotten if it is physically unrecoverable;
WARNING: if possible, Hosts should be 'ejected' from the Pool instead.
WARNING: Once a host has been forgotten it will have to be re-installed.
WARNING: This operation is irreversible.
Type 'yes' to continue
yes

Returning to XenCenter I found that the orphaned host entry had been removed.

 

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Xenserver: How To Create A Custom Kickstart Template via the CLI

100-Frankenstein-Smiley-Free-Halloween-Vector-Clipart-IllustrationIf you are reading this post, then you should know that I have been spending a lot of time as of late trying to learn XenServer, and I am doing my best to get Xenserver to do my evil bidding.

When I first took a look at XenServer I was dissapointed to find that you cannot PXE boot a VM unless you use the "Other Install Media" Template. However, when you use this template you are not building a fully paravirtualized vm, and you loose some functionality on your vm (like hot adding a virtual disk).

So lets say you want to kickstart a Centos 5 64-bit vm. Traditionally in XenServer,  you need to create a new vm based on the "Centos 5 (64-bit)" template and then point your vm to your kickstart media and ks config file. Being that this is a manual process, and I am trying to automate building virtual machines, I started searching for a better way to make Xenserver do what I wanted… I think I may have accomplished my goal.

So the first thing I did was create a new vm via cli. This step spits out a UUID for your new vm.

#xe vm-install template=CentOS\ 5\ \(64-bit\) new-name-label=Centos5.4_Kickstart

Now setup your boot params to point your new vm to your kickstart config file

#xe vm-param-set uuid=0415bc6c-6129-9bc2-26d7-e15625cf85a1 PV-args="ks=http://<my_kickstart_server>/kickstart/ks/centos5-u4_x86_64.cfg ksdevice=eth0"

Then tell your new vm where to find its install DVD.

#xe vm-param-set uuid=6aaf7e10-59e4-9895-9c7b-6eee32eab9f1 other-config:install-repository=http://<my_kickstart_server>/centos5-u4-x86_64/disc1/

Now figure out the UUID of your Kickstart VLAN

#xe network-list

Create a VIF (virtual interface) on your kickstart vlan.

#xe vif-create vm-uuid=0415bc6c-6129-9bc2-26d7-e15625cf85a1 network-uuid=f5a61f5b-f17c-ac40-0995-c41c3a5a3ea3 device=0

Now on the next step i cheated – I used XenCenter to quick create a vm based on my new template.

Now when I create a new vm from this template, it startes to kickstart on boot. My next steps are to create multiple templates, each based on my different kickstart images/configs. Then figure out how to set their ips and hostnames.

Hopefully that post is coming soon.

 

How to Create A Dedicated Storage NIC in XenServer

Wickenburg-networkIn Vmware ESX, when using NFS storage, you are required to create a separate and additional vmkernel portgroup to access your NFS storage. This way ESX Management traffic travels over one port group and NFS traffic travels over another.

In Xenserver the concept is similar; however executed much differently.

First and foremost you need to be aware of a few limitations in XenServer. While XenServer does allow you to create a dedicated nic (or bond) for NFS traffic, this nic must remain unmanaged by Xenserver. In contrast, a XenServer's management traffic travels over its "Management interface", which obviously has to be an interface that is managed via XenServer.

Allow me sum this up. You cannot share a nic or nics between management traffic and NFS traffic. This means that you are going want to create a bond for management traffic and a bond for NFS traffic you are going to need 4 free interfaces on your Xenserver box.

Now it is possible to use VLAN tagging and route your Management traffic and virtual machine traffic over the same physical interfaces. However its important to know that XenServer does not support VLAN tagging on the Management interface, so whatever VLAN you use for management, it must be the native vlan on the ports configuration.

The information below is from the Admin Guide for XenServer 5.5

Switch ports configured to perform 802.1Q VLAN tagging/untagging, commonly referred to as ports with a native VLAN or as access mode ports, can be used with XenServer management interfaces to place managementtraffic on a desired VLAN. In this case the XenServer host is unaware of any VLAN configuration.

XenServer management interfaces cannot be assigned to a XenServer VLAN via a trunk port.

Bottom line; its probably best to have seperate physical connections for your management traffic and NFS traffic.

Also, according to the Admin Guide, your NFS network should not be routed. See the words below and read them thusly.

"Before dedicating a network interface as a storage interface for use with iSCSI or NFS SRs, you must ensure that the dedicated interface uses a separate IP subnet which is not routable from the main management interface. If this is not enforced, then storage traffic may be directed via the main management interface after a host reboot, due to the order in which network interfaces are initialized."

Ok now that we got all that out of the way, lets actually create our dedicated storage nic.

First we need to get the uuid of the pif (physical interface) that we want to use. Note that this is just an example using a standalone interface.

#xe pif-list host-name-label=<"your_hostname>

Next we reconfigure our pif

#xe pif-reconfigure-ip mode=statc IP=<your-ip-on-nfs-vlan> netmask=<your-mask> uuid=<pif-uuid>

#xe pif-param-set disallow-unplug=true uuid=<pif-uuid>

#xe pif-param-set other-config:ManagementPurpose="Storage" uuid=<pif-uuid>

Alternatively you can use xe pif-forget to remote the interface from Xencenter database and configure it manually via the XenServer Kernel like you would any other interface in Linux, however this could be more confusing in the long run.

XenServer 6.0 Release Notes & Administrator Guide

Citrix

Hello World!

XenServer 6.0 was released in late September, 2011. I am currently working on building out my test cluster, as I expect to role out our first XenServer Server (hey that's redundant) in the next few weeks. I expect to be posting a lot more on the subject as I become more familiar with the product.

 

Release notes below.. includes new features:

http://support.citrix.com/article/CTX130418

Xenserver 6.0 Administrators Guide below for those of you who can read.

http://support.citrix.com/article/CTX130421

 

Citrix XenServer Tech Specs – Minimums & Maximums

Meow_cat_art The link below is basically the minimums and maximums document from Xenserver 5.6. Have been looking for this document for days and now I have it, and its all mine.

XenServer Tech Specs — Link

Below are the specs for a physical host for those of you who do not care to click on the link above. Look 512GB memory … nice!

 

  • 64-bit x86 server-class system 
  • CPU: 1.5 GHz minimum, 2 GHz or faster multi-core recommended
  • Intel® VT or AMD-V™ required for support of Windows guests
  • 2GB to 512GB physical memory
  • Up to 64 logical processors
  • 100Mb/s or faster NIC
  • Up to 16 physical NICs
  • Local, Fibre Channel or SAN boot disk with 16 GB of space minimum, 60 GB or more recommended

Getting Started with XenServer: Features and Licensing

10540402-xenserver This post is pretty much a bunch of links that I have found that I am using to get up to speed with ZenServer. I've got a new virtualization project just around the corner and Vmware is no longer a good fit for us.

The link below is from Citrix.com and compares the various features in the different versions of XenServer.

http://www.citrix.com/English/ps2/products/subfeature.asp?contentID=2300456

And the link below explains XenServer licensing. There are three licensed versions of XenServer, and of course a free version. The specific version that I am looking at is Enterprise, which only lacks a few features available in Platinum. Street price for Enterprise is $2500 per server.

http://www.citrix.com/English/ps2/products/subfeature.asp?contentID=2313292

If you are interested in test driving a licensed version of XenServer, you can use the link below to register for a 45 day trial.

http://deliver.citrix.com/go/citrix/ceXenServerTrial

Last but not least, the link below is to Citrix's documentation portal.

http://support.citrix.com/productdocs/

Now just need to find the minimum and maximums docs and I should be good to go.