Now that VMware has announced App Volumes 3 and Unidesk has announced Unidesk 4, it's time for an updated comparison of the two application management solutions.
Unidesk's marketing people will say Unidesk is the original inventor of application layering, with the most customers, the most apps delivered, and the most mature technology. But App Volumes is about to release version 3 and has some good market traction now, too.
VMware's marketing people will say App Volumes pioneered real-time app delivery, with the ability to add apps at logon so that non-persistent VMs can be personalized on-demand. But Unidesk now has this ability in version 4, and is taking it a step further by providing hot-add for Citrix XenApp sessions.
I've now run both solutions in the lab, so I'm going to try to cut through the marketing FUD. Here's my take on what the technical differences are, why they matter, and what I'm hearing from the customers I talk to every day as a Unidesk solution architect.
By the end, you'll see why I think Unidesk is the right choice for customers who want maximum app compatibility, simplicity, open support for any platform, and an easy path to the cloud.
App Layering 101
Let's start with a quick refresher on the tech for those who don't know what app layering is.
Gartner recognizes Unidesk and App Volumes as the two top solutions in a new category of next-generation Windows application management software called “application layering.” With layering, IT admins can package a Windows app just by running the app’s normal setup procedure. The package is stored as a virtual disk (VMDK, VHD) which can then be delivered to any number of machines (e.g. virtual desktops, XenApp servers) by attaching the virtual disk and using file system and registry virtualization to merge the virtual disks together. This eliminates the need for any further installations to deliver the app. You essentially get an "install-free" environment whether you're pushing apps to 5 users or 50,000 users.
Layering is gaining rapid market adoption because it is faster, easier, and more reliable than any other Windows application management technology. This includes the agent-based "silent install" approach used by legacy PC management tools, the process isolation approach used by traditional app virtualization, and the streaming/publishing approach used by remote desktop session host (RDSH) technologies.
Before I get into the tech differences, I'll answer the cost question, since I get asked this all the time. From what I can tell, the cost of App Volumes and Unidesk is about the same. Street price for both is in the $60-120 per concurrent user range stand-alone, depending on features, volume price breaks and educational discounts. App Volumes is also included as part of VMware Horizon Enterprise, so its cost is embedded in the price uplift over the cheaper Horizon Advanced edition. Though I'm told you should look closely at how that will impact your renewal.
Now let's get into the technical differences between App Volumes and Unidesk. I've organized them based on the questions I hear most often from customers, and then I explain why the differences matter.
1. What Can Be Packaged & Delivered?
Unidesk is the only "full-stack" layering technology. It can package and deliver the entire Windows workspace as modular virtual disks: the Windows operating system itself (OS layer), apps (App layers), and a writable Persistent layer that captures all user settings, user-installed apps, and data.
App Volumes is an above-the-OS layering technology. It offers app layers (AppStacks) and a writable user volume.
Why It Matters #1: Unidesk Offers Greater App Compatibility
Unidesk starts early enough in the Windows boot process to package and deliver 99%+ of the apps that are out there, including apps with boot-time drivers (e.g. printers, scanners), apps with deep Windows dependencies (e.g. Internet Explorer), apps that start very early in the Windows boot sequence (antivirus, XenApp VDA), and apps that need to be running when users are logged out (e.g. Imprivata OneSign, VMware Horizon View agent, Citrix Receiver).
App Volumes starts running too late for these apps, so it has many of the same "last 30%" limitations as traditional app virtualization technologies. To deliver these apps, you'll have to build them into your Windows images. The whole point of any app virtualization technology is to separate apps from the OS so they only have to be managed once. When you can't manage them all the same way, it can end up creating more cost and complexity.
Why It Matters #2: Unidesk Eliminates Image Management
Unidesk manages the Windows OS and all apps, so you no longer have to manage multiple images. One OS layer and one set of app layers can be used for all virtual desktops and XenApp/RDSH servers, no matter how many different configurations you need.
App Volumes doesn't manage Windows and all apps, so you'll have to manage them in other ways. Usually that means creating and patching multiple gold images, which adds management overhead and increases OpEx.
2. How and When Do Layers Get Delivered?
Unidesk and App Volumes can both deliver layers at user logon based on user identity (AD user account or group membership). Both products have a type of "in-guest layering" technology, in which the assigned virtual disks are mounted to a running Windows guest VM. App Volumes was the first to offer this "hot-add" or "on-demand" app delivery capability. Unidesk now offers the same capability with its Elastic Layering technology, but takes it one step farther with the ability to deliver layers at logon to individual Citrix XenApp or RDSH sessions (basically giving traditional server-based computing/terminal services the same app customization and personalization capabilities as VDI).
Unidesk also offers a second option - the ability to deliver apps as part of a "Layered Image" using layering technology that runs outside the Windows guest. This out-of-band layering option lets admins combine a Windows OS layer and any combination of app layers pre-boot into a full-blown image that can be delivered through existing provisioning technologies such as Citrix Provisioning Server and VMware Horizon View Composer.
Why It Matters #1: Unidesk Eliminates Image Management
With Unidesk Layered Images, you no longer have to manage multiple images in VDI or XenApp/RDSH environments. Even if you have lots of silos, you only have to manage and patch Windows OS and app layers once, and let Unidesk automatically generate the images needed for any collection, pool, or delivery group.
App Volumes only offers in-guest layering. It doesn't deliver the Windows OS, so it doesn't really solve image management.
Why It Matters #2: Unidesk Can Better Optimize Login Times
In-guest layering impacts the login time of a user no matter what solution you use. The more virtual disks that are attached at login and processed through the layering technology, the longer the login time will be. Having a way to optimize login times becomes critical, especially in industries like healthcare, where less time spent logging on translates directly to more time spent with patients.
Unidesk Layered Images have no impact on performance (the applications are already native in the image), allowing architects to reduce the number of virtual disks that need to be attached at login. The key here is that IT now has the ability to choose the right delivery method for each application. Since you can deliver apps in different images without worrying about image management, you can choose to deliver common apps used by many users in a Layered Image, then use Elastic Layering to dynamically attach the one-off or department-specific apps at login.
When real-time app delivery is needed, Unidesk Elastic Layering optimizes performance by mounting the virtual disks directly through the VM, eliminating additional load or delays associated with attaching the layer disks at the hypervisor level. This translates into significantly quicker in-guest mounts and login times, especially in large environments with heavily loaded vCenter instances.
App Volumes only offers in-guest layering, and must round-trip through the hypervisor to mount its virtual disks. This is why the App Volumes best practice is to group as many apps as possible in a small number of AppStacks, and then limit the number of AppStacks per user to a small number (i.e. 5-7). This is also likely the reason behind the new "AppToggle" feature in App Volumes 3, which allows you to put lots of apps into an AppStack, but then control how many are actually delivered at logon.
Why It Matters #3: Unidesk Offers Greater App Compatibility
The only way to deliver the last 30% of apps I listed above - apps with drivers, deep Windows dependencies, early-start services, etc. - is to deliver them with out-of-band layering. In-guest layering technology simply runs too late.
This is why Unidesk has 99%+ app compatibility, and App Volumes requires that you put the last 30%+/- of your apps into your gold images.
3. How Well Do Layers Interoperate?
Unidesk has spent a lot of developer-hours on layer interoperability. During its 5+ years on the market, advancements like cross-layer merge have been added to enable apps and plug-ins packaged in separate layers to interoperate as if they were hand-installed on the same machine. Unidesk has figured out how to merge the Windows driver store, .NET fusion keys created by the NGEN process, multi-string value registry keys, and other components that newer layering solutions haven't even hit yet. Unidesk also enables you to specify pre-requisite layers to ensure you have all the software you need to independently package plug-ins and apps.
App Volumes doesn't have these capabilities. The best practice is to package any apps that need to interoperate in the same AppStack.
Why It Matters #1: Unidesk Can Be Used by Lesser Skilled IT Staff
Unidesk enables app packaging to be handed off to Tier 1 IT and helpdesk staff because apps can be packaged without worrying about dependencies or groupings.
App Volumes requires more advanced and higher-cost IT skill sets, who will need line of business knowledge to determine which apps needs to interoperate and therefore need to be packaged together in the same AppStack.
Why It Matters #2: Unidesk Minimizes Package Duplication and Patching Overhead
Unidesk makes patches and updates easy and avoids package duplication by offering the flexibility to package any app in its own layer.
App Volumes will require the same app to be packaged in multiple AppStacks to work around the lack of cross-layer merge, causing the same app to be updated multiple times.
4. What Platforms and Clouds Are Supported?
Unidesk is an open solution that lets IT package apps once and deliver the same layers to different EUC platforms, hypervisors, and clouds. VMware vSphere and Microsoft Hyper-V are supported today, and, soon, any hypervisor, including Citrix XenServer, Nutanix Acropolis, and more. Microsoft is partnering with Unidesk to scale VDI with Hyper-V and RDS at cheaper-than-PC price points, and also to eliminate image management and simplify application upload for Azure RemoteApp. Citrix is partnering with Unidesk to simplify XenApp image management and extend XenApp to more apps and more users.
App Volumes, being owned by VMware, is primarily a solution for VMware Horizon and vSphere environments.
Why It Matters #1: Unidesk Maximizes End User Computing Flexibility
Unidesk can overcome application and image management challenges in VMware Horizon environments today, while keeping options open for the future. Organizations that want agility and freedom from vendor lock-in know they can migrate to different virtual infrastructures and end user computing solutions with Unidesk.
App Volumes is a solution that will require a long-term commitment to VMware.
Why It Matters #2: Unidesk Offers an Easy On-Ramp to Any Cloud
Unidesk app layers can be delivered to cloud platforms such as Azure just as easily as other hypervisors. Its unique ability to deliver full Layered Images will enable it to quickly integrate with any cloud platform.
App Volumes only supports VMware's cloud offering. Even if VMware wanted to support competitive clouds, the in-guest-only layering capability of App Volumes will be incompatible with most other cloud platforms.
5. What Integration is Provided for Existing Citrix Environments?
Unidesk offers 2 capabilities for Citrix XenApp and XenDesktop that aren't available in any other solution:
- Layered Image delivery to XenApp servers and XenDesktop desktops through integration with Citrix Provisioning Server and Machine Creation Services;
- Elastic Layering and Session Containers, which enable App layers and Persistent layers to be hot-added at user logon to individual XenApp user sessions.
App Volumes can deliver AppStacks to XenApp servers to simplify app configuration, but this is the same capability offered by Citrix AppDisk, Citrix's own app layering technology that is included free with all XenApp and XenDesktop editions.
Why It Matters #1: Unidesk Reduces OpEx and CapEx in Existing XenApp Farms
Unidesk Layered Images enable IT to use the same Windows Server and app layers for all XenApp servers – even across different silos and XenApp versions. Instead of having to patch multiple silos and vDisks every month, you only have to patch your Windows Server OS and app layers once. If you have 30 silos, Unidesk will cut patching OpEx to 1/30th of what it is now.
Unidesk also enables IT to deliver the same apps with fewer XenApp servers. Most XenApp customers deploy multiple silos because they need to deliver different combinations of apps. With Unidesk Elastic Layering, you'll be able to deliver any combination of apps with only a few silos, and consolidate away some servers to reduce CapEx.
App Volumes does not offer these capabilities or cost savings.
Why It Matters #2: Unidesk Extends Existing XenApp Investments to All Apps and Users
Unidesk extends XenApp with VDI-like capabilities. For the first time, every XenApp user can have different apps and persistent personalization across sessions. Unidesk Session Container technology creates a “wall” around each XenApp session so that Unidesk Elastic Layering can attach different virtual disks at logon based on user identity. Customers that want to avoid the cost of a whole new VDI environment can now extend XenApp to more users and more apps.
App Volumes does not offer these capabilities or the ability to extend XenApp.
6. How Resilient, Scalable, and Extensible is the Solution?
Unidesk's architecture has a number of new enterprise-class features that differentiate it from other technologies.
- Layered Images are standard images that can be used in almost any environment.
- Layers are portable. Unidesk can separate out platform-specific dependencies so the same layer can be copied or backed up to any platform or cloud using standard tools.
- Layers are self-describing. All of the information needed to hot-add layers into a Windows guest VM are located in standard XML files.
- Platform connectors can be written for any environment to leverage existing provisioning tools, workflow engines, and app stores.
App Volumes has more of a traditional client/server architecture.
- In-guest app delivery is the only option.
- Calls have to be made to a separate set of management servers and a SQL Server back end to figure out the user policy and determine which AppStacks need to be mounted. Calls are then made to vCenter to mount the virtual disks.
- Adding new hypervisors and cloud platforms will require deep integrations.
Why It Matters: Unidesk is More Fault Tolerant, Extensible, and Scalable
App Volumes has more dependencies on infrastructure. If App Volumes components aren't running, AppStacks aren't attached.
The Bottom Line
Unidesk and App Volumes both bring Windows application lifecycle management to levels far beyond what is possible with legacy technologies like agent-based software distribution, traditional app virtualization, and app publishing/streaming. Since the cost is about the same, the decision comes down to what's best for your environment.
Unidesk is a good choice if you want to:
- Deliver a broad set of apps that require 99%+ app compatibility and local install interoperability;
- Shift app packaging to your lesser-skilled helpdesk and IT staff;
- Eliminate image management across Horizon View pools;
- Eliminate image management across Citrix XenApp silos and delivery groups;
- Consolidate the number of XenApp servers needed to deliver your existing published apps and desktops;
- Extend XenApp to more apps and more users to avoid the high cost of VDI;
- Scale VDI for less cost than PC refresh with Hyper-V and RDS;
- Publish your apps through Azure RemoteApp;
- Future-proof app delivery so you can package once and deliver to any hypervisor, end user computing platform, or cloud;
- Integrate app delivery with existing workflow, provisioning, and app store technologies.
App Volumes is a good choice if you have:
- A small number of "last 30%" apps;
- Minimal requirements for app interoperability;
- Few images in your Horizon View VDI environment;
- Few silos/vDisks in your Citrix XenApp environment;
- No need to deliver more apps through Citrix XenApp;
- No need to offer greater personalization to Citrix XenApp users;
- No plans to use any hypervisor other than vSphere;
- No plans to move Windows apps to Azure or other clouds;
- No need to integrate app delivery with existing workflow, provisioning, and app store technologies.
Again, this is my take. If you have other thoughts, I'd be happy to hear from you. Comment below or email me at gduescher (at) unidesk (dot) com.
Update - March 21, 2016
A bunch of you already took me up on my offer and emailed me with comments and questions. Here they are with my responses. Keep 'em coming!
Q: Can’t the other app layering solutions eliminate OS/image management too, since they rely on the delivery/provisioning system (e.g. Citrix PVS, View Composer) to push out the Windows gold image?
In theory, yes. But they all have the same "last 30%" issue. This is why so many XenDesktop/XenApp/PVS and VMware Horizon/View Composer environments of any size have multiple images - to deliver the apps that can’t be separately packaged or virtualized. App Volumes has the same limitations as the other above-the-OS app management solutions, so image sprawl will continue to exist. Unidesk’s ability to deliver all apps separately is why there are so many examples of customers who are only managing Windows and apps once. And now with Unidesk’s ability to deliver layered images through the existing delivery systems, you can build apps into as many images as you want, and you’ll still only be patching Windows and apps once.
Q: Can't App Volumes also bind layers on boot?
Not with App Volumes 3. Earlier versions of App Volumes let you assign a virtual disk (AppStack) to a machine at VM start instead of at user login, but this is no longer available. Even if it was, simply hooking a layer at boot doesn’t make it compatible with boot-level applications. App Volumes still requires that the machine boots and its services start before it can run. It does not pre-compose boot-level requirements into the registry and start running at the same time Windows does like Unidesk. This is why you can’t package the Horizon View agent, the Citrix VDA, anti-virus, Imprivata OneSign, etc. with App Volumes like you can with Unidesk.
Q: Why is layer interoperability so important? I don’t understand the issue with App Volume’s requirement to put dependent apps in the same AppStack.
Packaging apps in individual layers is the simplest way to deploy apps. Once you force IT to put apps into the same AppStacks (or the same Citrix AppDisks) for interoperability, you create complexity and duplicate packages. We’ve already learned that lesson from App-V and ThinApp, which have the same requirement. Let’s take some real world examples. I work with a lot of law firms. They all use a ton of .NET plug-ins that sit on top of Office and Outlook and that need to interoperate with those base apps. With Unidesk, I put Office and plug-ins A, B, C, and D all in separate layers. I assign Office, A and B to the Property Attorneys group and Office, C and D to the Tax Attorneys group, and I update them all once. With App Volumes, I have to create an AppStack with Office, A and B and another AppStack with Office, C and D. I’m now patching Office twice. And this is a simple example. The more apps and the more configurations you have, the more complex this gets. Check out our webinar with Ober Kaler, and our case studies with Bernstein Shur and HKM Law Group to hear it straight from some law firm customers. I see the same thing from our healthcare customers who need EMR to interoperate with other apps, banking customers who need their core financial app to interoperate with Adobe and other apps, etc. This challenge exists in every industry.
Q: CloudVolumes’ customer base was mostly Citrix, so why would App Volumes have any dependencies on VMware?
CloudVolumes wasn’t on the market very long and didn’t have time to really build any kind of customer base before being acquired by VMware. But I'm sure they have some Citrix customers. While App Volumes has retained support for Citrix, all new advancements for speed of dynamic attachment are geared toward vCenter and Horizon View. I’m not sure why anyone would be surprised at this. VMware is clearly trying to use App Volumes as a lever to get Citrix customers to move from Citrix XenApp to Horizon View and choose AirWatch over XenMobile. So why would anyone think that AppVolumes is not being optimized for VMware technologies? Just look at all the pre-release hype around Project A2 – the combination of App Volumes and AirWatch.
Q: You talk about Unidesk as better suited for the cloud than App Volumes. Why is that?
Because in-guest layering (dynamic attach) is App Volumes’ only method of app delivery, and that’s not compatible with most cloud platforms. Having to attach 4, 6, 10 virtual disks in the cloud through VHD mounts is a non-starter, because you have no access to the hypervisor and you’re usually facing a limited virtual disk count. Cloud platforms like Azure RemoteApp generally require full images, which only Unidesk is designed to do. With Unidesk’s out-of-band layering, you can create full layered images for delivery through Citrix PVS/MCS, Horizon View Composer, Azure RemoteApp, etc. Then for the platforms that support in-guest layering, Unidesk gives you the second Elastic Layering option.