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Virtualized desktop infrastructure (VDI) can offer solid benefits such as centralized administration, user self-service and resource consolidation. Take a look at one company's VDI experience.
Intrigued, I asked Derek for details on their implementation and our discussion became an article for Tech Pro Research as a result. Derek was even kind enough to set me up with a test account in his environment and gather some interesting screenshots.
Here’s the situation
“So, we previously had several dozen developers running Red Hat Linux 5 server on their workstations – mainly Dell Precision 490, T5400 and T5500 desktops,” Derek told me. “They ran tools like Squirrel, Eclipse, and Accurev. The developers also had Windows VMs running within VMWare Player so they could access Microsoft Office, Windows drive mappings and so forth. The virtual machine was really incidental to their primary desktop functions, which were to compile code, run builds, and otherwise develop software for the company.
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These workstations are powerful, but they’re also expensive – and many had upwards of 16 or even 32 Gb of RAM. The real pain point had to do with the fact these machines HAD to be kept running for long periods of time so that compiling and builds could finish. However, if the machines had a problem, like losing power or needing to be patched, this was really inconvenient for the developers. They had far too many interruptions in their coding, and it got to be too cumbersome to keep this expensive hardware running.
Not only that, but frequently the developers wanted other Red Hat installations – both 5 and 6 - for different tools and purposes, or they moved from group to group and required different workstation builds, so we spent a lot of time building physical systems. This was compounded by the fact developers were being hired on a pretty frequent basis so we were setting up new machines over and over. We finally hit a tipping point and realized it was time to utilize the benefits of virtualization.”
Here’s the solution
Derek and his team decide to take advantage of Red Hat virtualization to build a VDI environment to meet their developers’ needs through the use of centralized virtual machines based on a template or “gold image” that could be customized or refreshed. Their environment runs on a Red Hat Enterprise Virtualization Cluster and allows for isolation of tasks, a scalable architecture, and a consistent platform.
The expensive workstations were replaced with Windows 7 laptops; largely Dell Latitude E6330 systems. In an ironic switchabout, the developers now run Windows 7 as their primary workstation but connect to the VDI system’s user portal via a browser and a special client application called Spice (Simple Protocol for Independent Computing Environments) which provides a Remote Viewer akin to Remote Desktop in Windows – except that it connects via a dedicated network path. All laptops hook into docking stations with dual monitors; this company has used multiple monitors since its inception for better productivity.
Users log in with their Active Directory credentials (via a Lightweight Directory Access Protocol connection to the company domain controllers) and now create and administer their own virtual machines, including snapshots, cloning and deletion. They can have multiple Red Hat Enterprise Linux 5 or 6 virtual machines depending on their needs. These virtual machines offer plenty of storage, multi-core CPU and 16 Gb or more of RAM. Permissions are set up so developers can administer only the VMs they have been granted access to. They can perform their work in their virtual machines without having to reboot or worry about local workstation problems and the company saves money by providing mid-level laptops rather than pricey desktops to the programmers.
This sounds enticing, however it’s important with VDI to keep in mind that a poorly-planned out migration merely shifts costs from the front-end (user workstations) to the back-end (virtualization environment), so getting the most bang for the buck from the servers is a key priority. The servers should offer plenty of capacity but that capacity should be used or reserved for future growth.
Back end system specs
The Red Hat Enterprise Virtualization Manager environment (RHEVM) runs on several Dell PowerEdge R620/820 servers. There is one RHEV manager and several hypervisor servers to share the load. Each hypervisor has four ethernet connections: two for the RHEV/VM network and two for the SPICE network, one of each going to a different Brocade switch.
The servers have the following:
- 2 CPU sockets/8 Cores per socket
- 500 Gb RAM with 10 Gb Swap (275 Gb swap for some) / 260 Gb of RAM with 145 Gb Swap
- 33 Tb of shared storage on EMC SAN via fiber using the following volumes:
o Two 600 Gb (300 Gb free)
o Fifteen 2140 Gb (average 900 Gb free)
The following software is in use:
- Red Hat 4.4.7-4 with hypervisor RHEV Hypervisor - 6.5 - 20140324.0.el6ev
- Red Hat Enterprise Virtualization Manager 3.3.1-0.48.el6ev
- Linux 2.6.32-431.11.2.el6.x86_64 kernel
Checking out the User Portal
The user portal allows users to log in from any browser to access or administer their virtual machines. Here’s how they go about it:
Once users log into their domain they are presented with a screen similar to the following, which shows their virtual machines:
In the above example, I have a virtual machine with my name on it. If I had multiple virtual machines these would also be listed. Note the four buttons to the right of my VM name; these allow me to run, shut down, suspend or power off the VM, respectively. There is also a “Console” button which lets me access the VM (more on that in a bit). The button to the right of THAT offers console configuration options:
Since they use the SPICE client (and a browser plug-in) this is set appropriately, but it’s interesting to note the other options such as VNC or Remote Desktop.
Getting back to the main screen, if I click my VM it shows me more information on the bottom of the screen:
You can see the virtual machine specs and relevant details listed here; I have 16 Gb of memory, 8 CPU cores and two monitors.
Clicking “Network Interfaces” displays the following:
Pretty vanilla stuff here, since it’s just the one NIC, but I can view network details such as speed and MAC address.
The “Disks” tab shows me this view:
This displays the virtual disk details, type of provisionining, creation date and so forth.
The “Snapshots” tab will allow users to work with virtual machine snapshots:
This feature alone provides an incredible set of tools to users; they can handle their own snapshots, allowing them to make changes to their virtual machines and safely back these out if needed. Derek informed me this feature alone has offered countless benefits to the company. Emergency rebuilds are a thing of the past.
Clicking “Permissions” shows who has access to this virtual machine; in this case only myself:
The “Events” tab shows all events pertaining to virtual machine activity such as console session usage and startup details:
“Applications” shows details about what’s running on the VM (but not the OS level, which is Red Hat Enterprise Linux 6):
The “Monitor” tab shows the CPU, Memory and Network usage:
And finally the “Sessions” tab will show who is logged into the VM:
That’s not all, however. Clicking “Resources” in the left-side toolbar shows me what’s happening with my virtual CPUs, memory, storage and disks/snapshots:
Getting back to the Virtual Machines tab, clicking the “Console” button will launch my VM via the Spice client Remote Viewer:
Once I log in I will see the following KDE desktop (I could also specify GNOME) which of course is just like a real live physical machine:
What if I want to create new VMs? Simple – back at the main user portal page there is a “New VM” link.
Once I click this link I am presented with the following dialogue box:
From here I can specify the setup details, including what template to use (“Blank” is the standard Red Hat Enterprise Linux 6 template), whether it is optimized for server or desktop, and the network interface details. Clicking “Console” lets me set the monitors to be used (two). “Advanced Options” provide memory/CPU settings, time zone, high availability and boot options. Once I create the VM it will show up in the user portal where I can log in and work with it.
Checking out the admin portal
The user portal offers flexibility and self-service options for business employees (and their system administrators) to get their work done in a fast-paced environment. However, it’s also worth taking a look at the separate admin portal to this environment, which provides the Linux administrators with even more VDI power. Let’s step through some screenshots to illustrate what they can do. Note: virtual machine and domain names have been blocked out in order to preserve confidentiality.
Upon logon to the admin portal you can see the tabs across the top as well as the options on the left which provide insight and control features. The tabs are where most of the action takes place, so I’ll cover each one.
The first, “Data Centers,” shows the virtual data centers – in this case the unused default and the DWI desktop environment. More could be added here as the company’s needs expand.
The Clusters tab provides a view of the clusters that are running:
A cluster is a container that holds hosts (hypervisors) and VMs. Clusters have logical networks assigned, use the storage domains attached to the datacenter, and can share templates.
“Hosts” shows the actual physical servers which have been allocated to this setup, along with their status and resource usage:
Next up we have “Networks” which is self-explanatory:
Then there is “Storage” which can tell you at a glance how much space has been allocated and is being used.
“Disks” takes the storage concept further by showing all the virtual disks in use along with their status (remember, the host names have been blocked out since these contain user identity details):
Now we come to “Virtual Machines” which really demonstrates the nitty gritty of what’s going on here:
This screen not only shows virtual machine details but many administrative controls as well. VMs can be added, removed, migrated to other hosts, snapshotted, turned into templates, and more.
“Pools” and “Volumes” do not show anything since these have not been set up, but the “Templates” tab reveals the available virtual machine template which can be used to set up new images:
Finally, the “Users” tab shows the domain users authorized to log into this environment.
Issues with VDI
VDI has been a great solution for this organization, but there have been some challenges as well. Developers have reported issues with copy and paste, the ability to stretch or resize their virtual machine screen across two monitors, Spice client crashes and – most interestingly of all – a weird authentication problem whereby logging into the virtual machine causes their credentials to be passed to Active Directory several times (nine at last count) meaning users can find themselves locked out almost immediately just by one mistyped password! All of these are being actively investigated with Red Hat support and will eventually be resolved, but it’s important to note that there is almost always some turbulence with any new endeavor. All issues are tracked and discussed weekly with development managers so the problems can be checked off and the IT department can ensure users are satisfied with the delivered solutions.
The centralization of resources works well for this company and having multiple hypervisors lets them spread their virtual machines among several servers – but this does not eliminate the need for virtual machine and server patching, of course. Reboots are still a part of life – though much more effectively planned out now - and careful analysis and monitoring of the resources involved is critical to ensure the programmers can do their jobs without overloading the hardware.
The key to a
successful virtualization implementation is making sure that your benefits
outweigh your drawbacks. Derek’s company no longer has to pay several thousand
dollars for a workstation for a new hire… but they also must maintain a fairly
expensive clustered server arrangement to provide that new hire with sufficient
programming resources. It has paid off well for them due to meticulous analysis
and budgeting of the hardware and software behind their Red Hat Enterprise
Virtualization platform and the reliability/scalability they now enjoy. However,
if not for careful management it wouldn’t have been hard for the project to go
off track and wind up consuming more capital and staff labor.
Derek advised me: “Take a look at your ‘before’ and ‘after’ figures before tackling something like this, and don’t forget to account for future growth. Always do an in-house evaluation rather than blindly relying on vendor promises, and most importantly, get buy-in from your users and department heads before giving the thumbs up. You’ll be the one building it, but they’re the ones who will be using it on a daily basis. Virtualization made sense for us because our developers have high-end requirements, but I don’t think we would have even considered putting their generic Windows VMs in an environment like this; there was no need since those ran fine on the local workstations so that would have just been wasted money.”