Virtualization How-To Part 2

The second problem most companies experience (including my first IT Job) is the updates that need to be performed to all desktop images on a daily, weekly and monthly basis. You have the Microsoft patches, the anti-virus patches, the application patches or updates and the list just goes on and on. Although they seem simple enough, patches and updates for a desktop image can have devastating consequences for a company when deployed incorrectly. Remember Joe down in IT from my previous postings? He cost the company thousands of dollars simply by pushing out a Microsoft patch that wreaked havoc on the environment. The answer? Citrix XenDesktop with Citrix Provisioning Services.

Citrix Provisioning Services allows you to take one “golden desktop image” and publish it to entire user communities quickly and efficiently. How is this any different from desktop PC imaging software like Ghost you may ask? Well once you have this image, you can update the image live and publish it out to your users without significant interruptions. The next time the user logs off and logs back in, they will receive the updated image quickly (unlike a 20 minute image process per PC). Problems with the image like Joe from IT had? Just a couple of clicks and your users are back on the image that was previously working for them.

So Provisioning Services is great if you have a bunch of physical PCs that you need to manage and don’t want the hassle of other imaging technologies, but what about using it in the Cloud? Well that is where XenDesktop comes in. Citrix XenDesktop allows you to take that PVS image and supply it to your end users virtually. Citrix XenDesktop moves beyond just the conventional desktop and into secure, on-demand, desktops as a service. Right now you’re thinking “That sounds awesome! But I don’t have either of those and they must be difficult to setup and install right?” Well they are easier to setup and install than you might think. Let’s look at the basic steps.

Step 1 – Gather the Components

This is probably one of the most difficult tasks. The system requirements for XenDesktop and Provisioning Services can be found here: Since you already have a hypervisor installed in your environment, you mainly need to decide how many CPUs and how much memory you want to be assigned to the VMs you create.

A couple quick notes for best practices: It is highly recommended to separate your Provisioning Server traffic from your production traffic by utilizing a separate NIC with a separate isolated VLAN and Subnet on the PVS server and VMs. By separating out the traffic, you will help ensure the quickest response time for your environment. In order to keep multiple images and revisions you will want to make sure you have plenty of space. A SAN environment is highly recommended however fast SAS drives on the provisioning server can also be substituted if SAN space is not available. Make sure that the space you select can handle at least 3 revisions of your desktop image for backup and restoration purposes (Don’t want to end up like Joe in IT do you?)

Step 2 Install the Software

Installation of the software components is relatively easy, with just a couple of clicks to run through. However if you are not feeling tech savvy, the great engineers at Accelera are always willing to help you out. Check out the Citrix EDocs site (Posted above) for step by step instructions on installing each product.

Step 3 Create your Image

Now that the software is installed, you are ready to create your base image. This can be Windows XP, Windows Vista, or Windows 7, pick your flavor and go through the basic installation procedures. Make sure that the VM has a NIC on both the production and PVS network. After you have completed the base installation procedures and/or updates, install the Provisioning Server Target Device Software and XenDesktop Agent and run the XenConvert wizard to place the image on the provisioning server. This part can be a little tricky as it requires that you have your vDisks on the provisioning server properly created and presented to your VM, so if you are looking for more in depth information than this blog or Citrix EDocs can provided, give the engineers at Accelera a quick call, and we can walk you through it in no time.

So now that you have the image you can take it and make simple VHD disk copies to have additional images you can manipulate without affecting this new “Gold” image. This is great for failback purposes.

Step 4 – Publish the Image with XenDesktop

With your image in hand (well stored on the Provisioning Server) it is time to publish it within XenDesktop. Running through and publishing the image to 50 VMs would be troublesome and take time. Citrix has been nice enough to provide us with the XenDesktop Setup Wizard. This Wizard (run from the provisioning server) allows you to take the one desktop image and make 50 desktops available through XenDesktop in a matter of minutes. Step by step instructions for using the XenDesktop Setup Wizard can be found here:

So now that you have the environment up and running. Any new clients are easy to add in minutes using Provisioning Services and XenDesktop. You have taken a process that used to take days down to a couple of minutes for simple clients or hours for more complex clients. Since you already have a hypervisor you can add hardware on demand without worrying about managing each individual piece or if one server fails it won’t affect the entire environment (remember always plan for an N+1). What about those pesky applications though? Providing a desktop is one thing, but installing and trying to manage all the applications is another. Well that is exactly what we will address in our next post.

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