Posts Tagged EUC

Key features for VDI storage

One of the biggest trends in IT infrastructure today is dedicated “storage systems” for VDI. I put “storage systems” in scare quotes because many of the vendors making these systems would object to being called a storage system. Regardless, the primary use case driving the sales of many of these systems is as a storage location for VDI. The reason for this is that traditional arrays have proven woefully inadequate to handle the amount and type of IO VDI can generate.

The architecture backing these systems varies greatly but when looking for a dedicated storage solution for your VDI environment, here are the top features I look for:

Speed. This one should be obvious but any storage system dedicated for VDI needs to be fast. Anyone who’s ever designed storage for a VDI environment can tell you that VDI workloads can generate tremendous amounts of most write-IO with very ‘bursty’ workload patterns. Traditional storage arrays with active-passive controllers, ALUA architecture and tiered HDD storage weren’t created with this workload in mind. Trying to design a VDI environment on this architecture can become (in some cases) cost and performance prohibitive. Indeed, many businesses are spending 40%-60% of their VDI budget on storage alone.

Today, the speed solution is being solved with a variety of methods. RAM is being used as a read/write location (e.g. Atlantis ILIO) for microsecond access times. “All flash” arrays are being purpose built to hold 100% SSD drives (Invicta, XtremIO, Pure, etc.). Adding to this, a whole host of “converged” compute/storage appliances are popping up utilizing local disk/flash for increased speed and simplicity (Nutanix, Simplivity, VSAN, ScaleIO, etc.) To reiterate, each of these systems I’ve mentioned can do more than just VDI, but VDI just happens to be a good use case for these solutions in many cases. If you’re looking for a place to put your VDI environment, the ability to rapidly process lots of random write IO should be of paramount concern and you should know that there are currently many ways this can be mitigated.

Data reduction. This one will be more controversial, particularly for non-persistent fanboys. Nevertheless, persistent VDI is a fact of life for many VDI environments. As such, large amounts of duplicate data will be written to storage and as a result, data reduction mechanisms become very important. De-duplication and compression will be the most effective methods and will be preferably in-line. Again, various solutions from Atlantis to Invicta, to XtremIO to Pure all offer these features but with very different architectures. If you have no persistent desktops then this feature becomes less important. However, data reduction can still be quite valuable in many non-persistent VDI architectures as well, as an example, XenDesktop MCS could greatly benefit from storage with de-duplication. I also find that many of my customers who start out thinking they’ll have only non-persistent desktops quickly discover during the course of their migration users who need persistence. Don’t be surprised by the need for this feature at a later point, plan for this at the beginning and make sure your storage platform has the appropriate data reduction features.

Scale. I don’t know how many VDI projects I’ve heard of where storage was purchased to support X amount of users only for the VDI project to take off faster and of larger scale than expected. The project then gets stalled because the storage system can’t handle more than the X amount of users it was designed for and the business doesn’t have enough budget to purchase another storage system. For this reason, any storage dedicated to VDI should be able to scale both “up” and “out”. “Up” to support more capacity and “out” to support more IO. The scaling of the system should be such that it is one unified system…not multiple systems with a unified control plane. The converged solutions are great at this, VSAN, Nutanix, et al. All flash arrays typically have this as well e.g. Invicta, XtremIO.

Ease of Management. This sounds basic and very obvious but make sure you evaluate “ease of management” when purchasing any VDI-specific storage solution. The reason for this is simple, any VDI-specific storage system is bound to have a much different architecture than any array’s you currently have in your environment. The harder it is to manage, the higher the learning curve will be for existing admins. My criteria for determining if a VDI storage system is “easy” to manage is this – “can my VDI admins manage this?” (and that’s no slight to VDI admins!). The management of the system shouldn’t require a lot of legacy SAN knowledge or skillsets. This makes the environment more agile by not having to rely on multiple teams for basic functions and doesn’t burden SAN teams with a disparate island of storage they must learn and manage. Again, many of the converged solutions are great at this as well as some of the newer AFA’s.

There are many other important factors in deciding what to look for in a storage solution for your VDI environment. Whatever the architecture, if it doesn’t include the above four features, I’d look elsewhere.

Note: Vijay Swami wrote an excellent article entitled “A buyer’s guide for the All Flash Array Market”. I found it interesting after I wrote this to read his thoughts and note how many of the things he looks for in an AFA are similar to my top features for VDI storage. Regardless, it’s good reading and if you haven’t already, check it out.

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Personal vDisks and Application Conflict Resolution

With the recent release of XenDesktop 5.6, Citrix has introduced the “Personal vDisk” feature into its XenDesktop product line.  See below for links on how Personal vDisks work, but the basic idea behind this technology is that it allows you to create pools of non-persistent desktops and still allow users to install applications on top of these desktops and those applications persist between reboots and base image updates.  This is a significant improvement over “dedicated” virtual desktops, where any updates to the base image would completely wipe out user customization.  This limitation forced administrators to apply updates to each dedicated desktop which would, over time, consume large amounts of storage space.  Needless to say, the Personal vDisk model is a welcome step forward for Citrix.

Now, with this release there was some exciting news about this technology’s ability to resolve application conflicts between user and admin installed apps.  For example, in this video, between the 6min-7:40min mark an interesting scenerio is given where a user installs Firefox 9 but the admin installs Firefox 10 as part of an image update.  The default behavior is that Firefox 9 will be “hidden” and Firefox 10 will be the application available to end users.  Another scenerio is given where both the user and admin have installed the exact same application, we are told that in this scenerio the user installed app is removed from their Personal vDisk to save space and only the admin installed app is utilized.  In the Personal vDisk FAQ, we’re also told that “Should an end-user change conflict with an administrator’s change, personal vDisk provides a simple and automatic way to reconcile the changes”.  With these things in mind, I set out to test this feature myself and see how this actually works.  As you might have guessed, things aren’t quite as “easy” as advertised.

What follows are the high-level steps I took to initially test this feature and try to get it to work:

Test #1

  1. Install Firefox 10 in the base/parent image
  2. Update Inventory and Shutdown, create new snapshot
  3. Update Image
  4. Install Firefox 11 as user
    At this point I was expecting to get an error or some warning denying me access to install Firefox 11 and that it conflicts with an admin installed app.  However, this did not happen and I was able to install Firefox 11 as a user.  This led to my next test.

Test #2

  1.  Install firefox 11 in the base/parent image
  2. Update Inventory and Shutdown, create new snapshot
  3. Update image
  4. Install firefox 10 as user
    Again, I was expecting some kind of error or warning at this point but it never happened.  As a user, I was able to install the older version of Firefox without any issues.  This led to another test.

Test # 3

  1. Install firefox 11 in base image/parent image.
  2. Update Inventory and Shutdown, create new snapshot.
  3. Update image.
  4. Install firefox 11 as user and observe more space being taken up on the Personal vDisk.
    Again, no warnings or errors at this point despite directly creating a conflict between a user and admin installed app and wasting space on the Personal vDisk.  I tried this same test with several different applications but had the same result each time.  Frustrated, I turned to the Citrix Forums and found the answer to why this doesn’t work.

As explained in that forum, the reason my tests didn’t turn out the way I thought they would is because Personal vDisk application conflict resolution does not happen proactively, during the time when a user is installing an application, but only after a base image update when files or folders have been modified and updated.  To borrow the example given in the forum and at a more granular level, say that “app.dll” is present in the base image.  The user installs an application or in some way changes “app.dll” on their virtual desktop.  This change will persist indefinitely until “app.dll” is once again updated in the base image.  At that point the inventory process will note that “app.dll” has been modified and the user changes to “app.dll” will be overwritten the first time the virtual desktop boots up after an image update.

I decided to test this out at the individual file level to easily verify the results.  Here is a file in C:\Test on my base image.  Note the size:

As a user, I modify this file by deleting all of the content and create another file in this directory.  Note the sizes:

Now, these user changes persist between reboots and even persist between image updates when this specific file is not updated.  However, when I go back into my base image and update that file (add a word), here’s what it looks like to the user after an image update:

As you can see, the admin changes in the base image have overwitten the user changes.  If we go back to my earlier examples we will see that this same behavior holds true for entire applications as well.  For instance, on Test #3, if I go back into the base image and reinstall Firefox 11, those files get removed from the Personal vDisk the first time it boots up and I now use the application as installed by the administrator from the base image .  On Test #2, if I go back in and reinstall Firefox 11 on the base image, I now see Firefox 11 as the end user and the Firefox 10 files are overwritten.

While the Personal vDisk feature of XenDesktop 5.6 is a definite step in the right direction, there is still some work that needs to be done with application conflict resolution.  Currently, the only way to be sure that admin installed apps overwrite any conflicting user installed apps is to regularly go into the base image and update or reinstall your applications.  Further, since the default behavior is for admin installed apps to “win” in the event of a conflict, administrators should take care when updating applications and images as they could inadvertantly be overwriting user installed apps that they didn’t intent to overwrite and this could lead to a confusing experience for the user (“Hey!  I didn’t install this version!?”).

Not having a solid application conflict mechanism in place isn’t a deal-breaker for me, after all, current “dedicated” desktops don’t have a solution for this either.  However, it is important to know how this works and when overwrites occur so you can properly manage applications in your environment and aren’t unintentionally creating a bad experience for your users.  A future post may delve into ways to modify the default behavior (admin apps overwriting user apps) but for now I put this out there for all who may be confused as to to how this works, as I was.

Here are some useful Personal vDisk links:

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ShareFile Review

Citrix announced its acquisition of ShareFile back in October and has recently allowed partners a free, one year, 20 “employee”, 20GB of space trial offer.  I’ve been kicking the tires on ShareFile for the past few weeks and wanted to share my thoughts.

What is it?
If you’re familiar with solutions like DropBox and SugarSync then you already have a pretty good idea of what ShareFile is – an online file sync and collaboration tool.  Unlike these other solutions, however, ShareFile is designed to be used by businesses.  ShareFile provides you with SSL encrypted storage and allows you to add users and assign permissions to particular folders and the ability to add additional administrators to help manage your data and users.  You’ll get configurable email alerts on file uploads and downloads and can even control the amount of bandwidth allotted to particular users in a given month.  ShareFile provides you with a customizable web portal ( that allows you to brand the website with your logos and corporate colors.  This web portal can be used as an alternative to FTP and even gives you the ability to search the site for particular files.  Other items of note:

Public Cloud
ShareFile is hosted almost entirely out of Amazon AWS and its services are spread across all 5 major Amazon datacenters.

-Desktop Widget:  Basically a fat-client that is built on Adobe Air that allows you to upload and download files to ShareFile without having to launch a web browser.
-Outlook Plugin:  Allows you to link to existing ShareFile documents and upload and send new files to ShareFile.  Administrators can even set policies that dictate that files over a certain size are automatically uploaded to ShareFile instead of attached using the corporate email system.  I’ve found this to be the most used ShareFile feature for me.
-Desktop Sync:  This gives you the ability to select folders on your PC to be automatically synced to ShareFile.  There is an “Enterprise Sync” as well that’s designed for server use and allows for sync jobs to be created under multiple user accounts.
-ShareFile Mobile:  A mobile website designed to be accessed from a tablet or smartphone.  In  addition, there’s a ShareFile app for iOS, Android, Blackberry and Windows Phone.

ShareFile has more features that you can read about on their website.

What does this mean for the enterprise?
Citrix is incorporating ShareFile into what it’s calling the “Follow-Me-Data Fabric”, which is comprised of ShareFile, Follow-Me-Data and GoToMeeting with Workspaces.  Citrix has long had the goal of allowing you to access your applications anywhere, from any device and they’re now attempting to extend this philosophy to your data as well.

In all honesty, it was initially hard for me to see this adding much value to the Citrix portfolio.  After all, doesn’t XenApp, XenDesktop, Netscaler, et al. already give me the ability to access my applications and data wherever I’m at?  My virtual desktop is accessible from almost any device already and all the data I work on is either saved on that desktop or accessible on corporate network shares from that desktop.  As I began to think about the future of IT though, and the shift to public and hybrid clouds, the strategy here became much more obvious.  While almost all the data I work on now is stored in one centralized location, the push to public and hybrid clouds will create a dispersion of corporate data across different cloud providers.  Corporations may be utilizing CloudCompany-A, B and C for SaaS applications and CloudCompany-D for portions of their infrastructure.  Even if you’ve only chosen one Cloud provider, most companies aren’t ready to dump all of their data and applications into the Cloud yet and may not ever.  This will obviously create a de-centralization of data that could get messy if not managed properly, and that’s where ShareFile comes in.

Working in conjunction with StoreFront and Follow-me-Data, ShareFile would give you the ability to centralize all the data stored in any private and public cloud infrastructures you’ve invested in.  You’d have StoreFront on the front-end tying your internal and SaaS applications into one unified interface and Follow-Me-Data and ShareFile on the back-end allowing you to access dispersed data in a centralized fashion.  That, at least, is the vision.  The key here will be integration – something Citrix has historically not done very well (e.g. VDI-in-a-Box, management consoles, etc).  To the user, ShareFile needs to go almost unnoticed and be seamlessly integrated into the Citrix product stack so that it does not feel like a separate technology.  Doing this will just make it natural for the user to store their public and private cloud data and access from anywhere.  If it’s seamlessly integrated into the products the user is already utilizing for their job then I think it will go a long way to securing corporate data.  After all, why would I put my corporate data on DropBox or SugarSync when it’s so much easier to get this same functionality with tools that are already integrated with the work I do?  And that too, will be a key factor in how successful this will be – corporations can’t lock this down to such a degree that it’s not easy for users to work with or else it will drive them to more “open” solutions.

In the end, I think this was a smart move that’s success will ultimately be dependent on the ever increasing push towards the public Cloud and Citrix’s ability to integrate this seamlessly with their already existing products.  It will also be interesting to see how DropBox and other similar companies respond to this.  Whether they want to define themselves as competitors or not, the bottom line is that there are currently tons of corporate data on DropBox and SugarSync and a well-integrated ShareFile means less data on these type of solutions.  Whether they add more “business-friendly” features to their products or are content with “personal” data remains to be seen.  And if they do add more features that allow companies more control of the data that is stored on them, how will Citrix respond?  Citrix has generally been very receptive to utilizing their services from multiple platforms (e.g. XenDesktop on ESXi/Hyper-V) so they might look to just provide integration with these other online file shares from Citrix Receiver as well.  And will this service always be hosted in the public Cloud or will there be an option in the future to host a ShareFile-like service for your company within your own datacenter?

There’s a lot that remains to be seen but overall, this appears to be a “win” for Citrix and a trend that other companies have already adopted as well.  End-user computing was a huge component at VMworld and Synergy this past year and I anticipate and look forward to even more rapid development in this space!


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