Reality Check: Scoping Virtual Desktop Infrastructure (Desktop Virtualization)
Virtual Desktop started as a simple concept: take the operating system, applications and data normally found on a business user’s physical desktop computer, and put them somewhere else. Somewhere else could be inside a virtual machine on a hypervisor platform, but regardless of where the bits of data are relocated, the key is that the data is no longer sitting on the physical desktop PC at the user’s location. Instead of the user touching the physical computer running their applications and holding their data, the user now connects to their desktop remotely. The requirements and technologies may vary for remote access, management and monitoring, but the idea is always the same – put the running applications and data, or the workload, in a safer, more secure location – the datacenter – on servers most likely managed by a server team. Sounds simple enough in theory, but so does mixing oil and water.
Virtual desktop is where two worlds collide – the desktop team and the server team – and each team has its own mentality. The "server" mentality is all about performance, uptime, disk I/O, and squeezing every last ounce of compute power out of a pool of physical resources. Server and application criticality levels are set based on what it costs a business in the event of a service degradation, failure, or catastrophic loss of those systems. The "desktop" mentality is different. Desktops are deployed in volume, and typically outnumber servers in an enterprise. Desktop uptime is important, but a desktop is not usually being used around the clock. With desktop, the financial impact comes when a user is unable to do their job because their desktop system failed. Many organizations have a policy that requires a desktop technician to replace a desktop PC if they are unable to fix the problem within a given amount of time. This helps protect the IT organization’s SLA to the business to which the user is part of. The concern of the desktop team is less about preventing failure, and more about how quickly a user can get back to work when a failure does occur.
Virtual desktop initiatives are often made the responsibility of both the desktop and server teams. Each team has a different mentality, and neither wants to deviate from that mentality. The result of this shotgun marriage results in "Virtual Desktop Bloat", or VDB. Side effects include desktop operating systems and applications are being loaded into virtual machines, placed on a very expensive virtualization platform, and connected to even more expensive storage. The cause of this behavior could be territorial, or perhaps each team wants to stick with what they know, but in either case it does not make sense financially.
Most enterprises considering virtual desktop technology are in the evaluation phase, which means it’s not too late to prevent a VDB condition. Here are some things to consider when scoping your virtual desktop solution:
1. What disk storage solution makes the most sense for my users? Technologies such as iSCSI and SATA disk are often overlooked, but should be considered for some or all of your virtual desktop deployments. These types of arrays offer a low cost of entry, which is important when storage makes up the majority of the cost in a virtual desktop deployment. Compared to the single ATA or SATA drive found in a corporate desktop PC, lower-cost arrays will at the very least meet the disk performance the user receives today.
2. Which hypervisor platform makes the most sense to host my users’ desktops? VMware set the bar high with their ESX bare-metal hypervisor technology, but competitors like Citrix XenServer and Microsoft Hyper-V are quickly catching up in feature functionality. You may choose to run one, a couple, or all three platforms in a tiered format. Just because one might be the gold standard for your virtual server deployments doesn’t mean it makes the most sense for your virtual desktops.
3. Do I need a connection broker? This has everything to do with your deployment model. If your organization is providing each user with their very own personal virtual desktop, then a connection broker is optional. Some virtualization management packages (such as DynamicOps Virtual Resource Manager) provide end-users with a web portal where they can click on a link and automatically launch a Microsoft Remote Desktop connection to the user’s virtual desktop. If your organization wants to use a pooled model, where no user actually owns a desktop, and the user is automatically assigned to an available desktop in the pool, then a broker is mandatory.
4. What about patching and antivirus updates? You may be able to use the same system used for your physical systems. Check with your software provider to see if your licenses are transferrable from physical desktops to virtual desktops. Also, OS vendors are finally coming out with their own robust tools for patching and deployment, at little or no cost to their customers.
5. Putting a large number of virtual desktops on a single server sounds risky – what if my server goes down? It’s a risk, but mostly mitigated by using shared storage. In the unlikely event of a server failure, the virtual machines containing the desktops can be brought up on other servers while the failed server is repaired. Since virtual machines are self-contained, and keep their identity regardless of where they are deployed, the host name, IP address and all the desktop’s contents will appear identical to the end user. Even virtual desktop deployments using a direct-connect, or non-broker model, will continue to function as designed.
6. What if I have users that require uptime similar to mission critical servers? Easy one – put them where they belong, on the highly available, high-performance virtualization infrastructure. Virtual Desktop Bloat doesn’t occur when a subset of power users have their VMs hosted on the high-end very expensive infrastructure, it occurs when ALL users end up on the high-end very expensive infrastructure.
While these questions only cover a small cross-section of deploying virtual desktops, they are fundamental enough to give your virtual desktop deployment plan the reality check it needs.
This article is the first in my new column, Virtualization Today, which focuses on the practical side of virtualization technology and its many applications. In the upcoming weeks we will dig deeper into the topics mentioned in this article, and arm readers with the information they need to make informed decisions while building their own virtualization strategies.