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More on VDI-in-a-Box and Personal vDisks

September 7th, 2012 | Posted by Sid Herron in Best Practices | Citrix | VDI | VDI-in-a-Box | Virtualization - (2 Comments)

In my last post, I talked about the new release (v5.1) of VDI-in-a-Box (“ViaB”) and some of the new features. One of those new features is the addition of support for Personal vDisks (“PVDs”). But before we get any deeper into the subject, let’s take a step back, and make sure we’re clear on why you would want PVDs in the first place.

Dedicating a VM to every user consumes a lot of storage space – and, even though local storage on a ViaB server is not as expensive as SAN storage, it’s still more expensive than the storage on a desktop PC. Plus you still have the same headaches of managing and updating every individual PC. That’s why we prefer to provision virtual desktops from a common master image. It takes up far less disk space, and when you update your master image, all of the virtual desktops that are provisioned from that master image get updated the next time they reboot.

On the other hand, since the master image is a read-only image, the user has no ability to make persistent changes to the VM. In a Citrix environment, we generally handle this by using the Citrix Profile Management tool (which is included with ViaB), which allows us to write user profile changes to a shared folder somewhere else on the network, so that unique user profile data will survive changes to the underlying master provisioning image.

But there’s only so much you can do with user profiles – and one of the things you can’t do is allow users to install their own applications. Personal vDisks, which were first introduced in XenDesktop v5.6, are intended to give you the best of both worlds, by creating a persistent virtual disk that is unique to the user and that is, in simplistic terms, merged with the provisioned image at logon time. The PVD can be used to store user-installed applications, user profile data, and even user files, if you wish. So you get to provision from a common master image and give users the personalization they want.

But there’s an interesting wrinkle in the way PVDs work in ViaB v5.1. One of the major selling points of ViaB is simplicity: you don’t need all the supporting server infrastructure that a full-blown XenDesktop deployment requires, and you don’t need shared storage. That, in turn, keeps the cost down. But while ViaB is smart enough to replicate your master desktop images to all of the servers in your ViaB grid, PVDs are not replicated across the grid. Instead, a given user’s PVD gets created on the local storage of whichever server in the grid that user happens to land on at first logon – and it stays there. ViaB will then insure that, for all subsequent logons, that user will be directed to the specific server that contains the PVD.

That’s a great solution…unless that server fails, in which case the PVDs on that server are no longer available, and their associated personal desktops are broken. In all of their presentations on ViaB v5.1, Citrix glosses over this point by stating that they recommend that you periodically back up the users’ PVDs, and that they have documented the steps required to do so. And they have. Here is the process for backing up and restoring PVDs, assuming that you’re running XenServer as your underlying hypervisor, straight from CTX134792 in the Citrix Knowledge Base:

  • From the ViaB management console, look up the personal desktop that you want to back up. Note which server in your ViaB grid is hosting this desktop.
  • Note the personal disk name of the personal desktop you are backing up. This will have an intuitive name like “Windows7x64p1386d2eaab7.”
  • Insure that the personal desktop is shut down.
  • Move to XenCenter (the management tool that comes with XenServer). From within XenCenter, navigate to the XenServer in your grid that is hosting the desktop, and use the XenCenter “Export” function to export a copy of that VM. Where will you export it to? Well, assuming that you don’t have shared storage, you’re going to have to export it to some kind of storage repository that the XenServer can see which you can later move to a different XenServer in your grid…like an external USB-attached hard disk.
  • If the ultimate bad happens, and you have to restore the backed up PVD, you need to again fire up XenCenter, and navigate to a surviving server in your grid that you plan to use to restore service. Use the XenCenter “Import” function to import the VM from your backup storage repository.
  • Once it’s imported, select the VM in XenCenter, and select the Storage tab. You will see that the VM consists of two disks, one of which will match the name that you made note of way back in step 2. “Detach” that disk from the VM, and then delete the VM. That will leave you with a virtual disk (your PVD) that is not associated with any VM.
  • Now go back to the ViaB management console, select the “User Sessions” tab, and, under the “Actions” link for the non-functional desktop, select “Repair.” ViaB will scan the data stores of each server in the grid until it finds the PVD, and prompt you for confirmation that this is what you really want to do. When you confirm, ViaB will destroy the remains of the non-functional desktop, create a new linked clone on the server that now contains the associated PVD, and attach the PVD to the new linked clone. The user can now log in again.

Bear in mind that you will have to follow this manual backup procedure for every individual PVD that you have in your environment, and, likewise, if you ever have to restore PVDs, you will have to manually restore them one at a time.

Show of hands: anybody else out there think that this might be just a tiny bit onerous?

Now, if you do happen to have a SAN, you could attach a unique LUN to each server in your ViaB grid, and, provided you’re using Hyper-V or VMware as the underlying hypervisor, use that LUN for storing your master images and PVDs. (ViaB on XenServer does not support multiple datastores, according to http://forums.citrix.com/thread.jspa?threadID=312411&tstart=0.) Then you could conceivably move that LUN to a different server in your grid in the event of a server failure, and have all your PVDs back…although you still need to do periodic backups of the PVDs (maybe with SAN snapshots?), because it is possible that a PVD could get corrupted if the ViaB host goes down while the desktop OS is in the process of writing to the PVD. And, as we’ve said earlier, you’ve now negated one of the big advantages of ViaB – no shared storage requirement.

Here’s the bottom line, in my opinion: Until they come up with a way to automate the backup and restore process for PVDs, or, better yet, find a way to replicate PVDs across the grid, PVDs should be used sparingly (if at all) with ViaB. And do not use PVDs to store user profile data or user-generated files. Instead, use the Citrix Profile Manager to handle the profile data, and standard policy tools like “My Documents” redirection to direct user-generated files to a shared folder outside of your ViaB grid. That way, your worst-case scenario is that your user may have to reinstall whatever user-installed applications may have been lost when the PVD disappeared.

Finally, please note that these concerns are not applicable to a full XenDesktop deployment. With XenDesktop, you will have some kind of shared storage, and your PVDs will live on that shared storage. So: XenDesktop, PVDs are great; ViaB, not so much.

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Citrix Releases VDI-in-a-Box v5.1

August 21st, 2012 | Posted by Sid Herron in Citrix | VDI | VDI-in-a-Box | Virtualization - (0 Comments)

We just learned that Citrix has released VDI-in-a-Box (“ViaB”) v5.1. There are a number of new features in ViaB v5.1, which you can read about in the Citrix on-line documentation library, but two of these features are particularly significant:

  • Personal vDisks – This feature was introduced in the most recent release of XenDesktop, but until now was not available in ViaB. It pretty much eliminates the need to ever provision dedicated virtual desktops for anyone, because the personal vDisk can store user data, personalization information, and even user-installed applications that then get merged at logon time with the VM that’s provisioned from your master image. You can update your master provisioning image at will without affecting what’s stored in the users’ personal vdisks.
  • Virtual IP – In prior versions of ViaB, users needed to explicitly point a browser at the IP address of one of the servers in your ViaB grid. If that server failed, they needed to explicitly point a browser at a different server in the grid. That obviously creates an opportunity for user confusion. The only way around it was to have some kind of load-balancer (e.g., NetScaler) in front of your ViaB grid. But with v5.1, your grid now has a virtual IP address. That virtual IP address is initially serviced by one of the servers in the grid, but if that server fails, another server will automatically take over.

There are several other feature enhancements, including tighter integration with the NetScaler-powered CAG Enterprise, support for HDX v5.6 Feature Pack 1, support for virtual desktops with multiple virtual CPUs, etc., and you can read all about them at the documentation link provided above. But the addition of personal vDisks and a grid-wide virtual IP address take care of what were, in our opinion, the two biggest things that ViaB was lacking compared to its big brother, XenDesktop. Well played, Citrix.

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What Licenses Do I Need….

May 16th, 2012 | Posted by Sid Herron in Application streaming | Application Virtualization | Citrix | Licensing | Microsoft | Remote Access | VDI | Virtualization | XenApp | XenDesktop - (25 Comments)

Earlier this week, I had a long discussion with a client (you know who you are) about what licenses they would need for a deployment of “zero client” devices. We’ve written a lot about Microsoft and Citrix licensing, about XenDesktop and XenApp, about the Citrix trade-up, etc., but it occurred to me that it might be beneficial to pull all the licensing information together into one post instead of expecting you, gentle reader, to have to sort through multiple posts to pull it all together.

So, let’s discuss Citrix licensing first, then move on to the Microsoft licensing.

First of all, if all you want to do is to deploy VDI (Virtual Desktop Infrastructure), and you have a limited number of users, then you should probably purchase VDI-in-a-Box. You can read more about this in our April Moose Views article about XenDesktop vs. VDI-in-a-Box.

If you decide that VDI-in-a-Box is not the right fit foryou, the next question you need to answer is whether to use XenApp licenses or XenDesktop licenses. Beginning with the introduction of XenDesktop v4.0, Citrix concluded, reasonably enough, that an organization that was deploying VDI probably wouldn’t get much leverage from a concurrent-use licensing model, because their concurrency ratio (by which I mean the ratio of total users to concurrent users) would be pretty close to 1:1. So XenDesktop v4.0 was introduced with a per-named-user or per-device license model. These licenses were roughly half the cost of the comparable XenApp concurrent-use license: XenApp Enterprise Edition, for example, carries an MSRP of $450 per concurrent user. XenDesktop Enterprise Edition carries an MSRP of $225 per user/device.

At the same time, Citrix made the decision to include XenApp rights in the XenDesktop license. So if you buy XenApp, you get only XenApp. But if you buy XenDesktop, you get both XenDesktop and XenApp – so you can use XenApp to stream applications to your virtual desktops, or have your virtual desktops function as client devices that run published applications that execute on the XenApp servers, or simply deploy a mixture of XenDesktop and XenApp to your user community depending on what delivery method is best for a particular use case. This is what Citrix refers to as the “FlexCast” delivery model.

This created the interesting situation where, because of the difference in license cost, if your concurrency ratio was less than 2:1, you were better off financially to purchase XenDesktop licenses even if all you really wanted to run was XenApp. And, since delivering what Citrix calls “hosted shared” desktops from XenApp servers makes more efficient use of the underlying hardware and storage infrastructure, the bias should probably be toward XenApp unless there is a clear use case for why users need to connect to individual desktop OS instances rather than a shared XenApp desktop (and it isn’t just appearance, because with XenApp v6.5 on Windows Server 2008 R2 we can deliver a XenApp desktop that looks and feels like a Windows 7 desktop). But, for the sake of this discussion, let’s move on down the XenDesktop trail.

Citrix has re-introduced a concurrent-use license option for XenDesktop, which is a better choice for organizations who want to deploy both XenDesktop and XenApp, but have a concurrency ratio greater than 2:1, but so far, I haven’t seen very many use cases where that license model made sense.

If you already have XenApp licenses, and want the ability to deliver VDI as well, you can take advantage of the Citrix trade-up program to transform your XenApp licenses into XenDesktop licenses. And if you trade up all of your XenApp licenses, you can get two XenDesktop user/device licenses for each XenApp license. So 250 XenApp licenses would become 500 XenDesktop user/device licenses. If you want more information on how the trade-up program works, and what your trade-up options are, check out the handy Citrix Trade-Up Calculator.

As of the release of XenDesktop v5.0 Feature Release 1, the license service got pretty smart in terms of how it managed those user/device licenses. This is good news for, say, a hospital, which may have devices that are used by multiple users and other users who use multiple devices. The license server can intelligently and dynamically reassign licenses between users and devices to make the most efficient use of the available licenses. For example, consider the following scenario for a brand-new environment where no licenses have yet been assigned:

  • User 1 logs on from client Device 1. The license server will, by default, check out a license to User 1.
  • User 1 logs off, and User 2 logs on from the same client device. The license server, now sensing that two different users have logged on from the same device, will take the license that was assigned to User 1, and reassign it to Device 1. Any subsequent users who log in from Device 1 will not cause any action by the license server, because Device 1 is already licensed.
  • If User 1 logs on again from a different client device, the license server will again check out a license to User 1 (so, at this point, two licenses are checked out: one to Device 1 and one to User 1). Since User 1 has logged on from two different devices, the license will remain assigned to User 1 unless/until manually released by an administrator (e.g., in the case of the employee leaving the organization), or unless User 1 doesn’t log on for a period of 90 days, in which case it will be automatically released due to inactivity.
  • Likewise, since two different users have logged on from Device 1, that license will remain assigned to that device unless manually released or automatically released due to 90 days of inactivity.

So…how do you know how many licenses you really need? There is actually a formula that will tell you that. You need to know how many total users you have (let’s call that number “A”), how many shared devices you have (let’s call that “B”), and how many of your users will use only shared devices (let’s call that “C”). The formula is A – C + B. So, if you have 1,000 total users, 300 shared devices, and 600 of your users will use only shared devices, you need 1,000 – 600 + 300 = 700 total licenses.

For more information on exactly how this works, see the Citrix Community Blog post by Christophe Catesson, which in turn links to a recorded session from Synergy 2011 that was a deep dive discussion of XenDesktop licensing.

Now for the Microsoft licensing component.

If you have users who will be executing applications on a XenApp server, you will need a Remote Desktop Services (RDS) CAL for that user, or for the client device that user is using. It is very difficult to manage a mixture of user CALs and device CALs in a Remote Desktop Services environment, so, in most cases, you’re going to be better off purchasing user CALs.

If you have users who will be attaching to a virtual desktop instance, the licensing requirements are different, depending on the client device. If the client device is a Windows PC whose Operation System is covered by Software Assurance, you do not have to purchase any additional Microsoft license to use that PC to connect to a virtual desktop. If the client device is not a Windows PC, or that copy of Windows is not covered by Software Assurance, you need a Virtual Desktop Access (VDA) license for that client device. VDA licenses are only available under the Open Value Subscription license model at present, meaning that you will continue to pay for them every year. Forever.

But wait! That’s not all! As Gabe Knuth outlines in a recent article on Techtarget.com, there is a very strange loophole in the VDA license terms. If you have a VDA license for your primary device (or if it’s covered by Software Assurance), you have what Microsoft calls “Extended Roaming Rights,” which allow you to also use your home computer to access your virtual desktop, or use your iPad when you’re at home or traveling. But, technically, it does not entitle you to bring your iPad into the office and use it there! To solve that (using the term “solve” loosely), Microsoft recently announced something called a “Companion Device License” (CDL) which allows you to use up to four other devices (in addition to the primary licensed device) to access your virtual desktop. No word yet on what the CDL will cost.

So let’s see if we can summarize what our client would need for a deployment of “zero client” devices (like, for example, the Wyse Xenith thin client).

  • You’re going to need some kind of Citrix license, either VDI-in-a-Box, XenDesktop, or XenApp.
  • Since the thin client is not a Windows PC, and therefore cannot be covered by Software Assurance, you would need to purchase a Microsoft VDA license for it.
  • If the thin client will be used only to attach to a virtual PC desktop and execute applications within that desktop OS environment, no additional Microsoft license is needed. However, if the thin client will also be used to attach to applications that are executing on a XenApp server – either directly or indirectly by having the Citrix client baked into the virtual PC desktop – you will also need a Microsoft RDS CAL.
  • You do not need an RDS CAL if you are only using XenApp to stream packaged applications to a virtual (or physical, for that matter) desktop for execution there. Since you are not actually utilizing Remote Desktop Services by executing code remotely on a Remote Desktop Server, no RDS CAL is required.
  • If you want to institute a BYOD program, where users can bring whatever client device they wish into the office and use it to access your VDI, you’ll probably need some of the new Microsoft CDL licenses.

If I’ve overlooked anything, feel free to submit questions via comments on this post, and we’ll try to get them answered. Let the discussion begin!

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Best Practices for Provisioning XenDesktop

May 11th, 2012 | Posted by Sid Herron in Citrix | Citrix Synergy | VDI | Virtualization | XenDesktop - (0 Comments)

We’ve written a lot here regarding XenDesktop’s two provisioning methods: Provisioning Services and Machine Creation Services. Earlier this week, at the Citrix Synergy Conference in San Francisco, there was a session specifically devoted to discussing those two provisioning methods, providing a high level overview of how they worked, the best practices for deploying each of them, and even some guidelines for how to determine which approach is best for your organization. For the benefit of those who couldn’t make it to Synergy – or those who did make it, but would like a better way to share that information with others in their organizations – that session was recorded and is available on Citrix TV. You can view it below:

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Some Straight Talk about VDI-in-a-Box

April 4th, 2012 | Posted by Sid Herron in Citrix | VDI | VDI-in-a-Box - (9 Comments)

There is a lot of buzz about Citrix VDI-in-a-Box (“ViaB”), and rightly so: it’s a great product, and much simpler to install and easier to scale than a full-blown XenDesktop deployment. You don’t need a SAN, you don’t need special broker servers, you don’t need a separate license server or a SQL Server to hold configuration data. Unfortunately, some of the buzz – particularly some of the cost comparisons you see that show a $3,000 – $4,000 server for 30 or more virtual desktops, is misleading. So let’s talk seriously about the right way to deploy ViaB. For this exercise, I’m going to assume we need 50 virtual desktops. Once we’ve worked through this, you should be able to duplicate the exercise for any number you want.

First of all, I’m going to assume that we are building a system that will support Windows 7 virtual desktops – because I can’t see any valid reason why someone would invest in a virtual desktop infrastructure that couldn’t support Windows 7. There are two important data points that follow from this: (1) We should allow at least 1.5 Gb per virtual PC, and preferably 2 Gb per virtual PC. (2) We should design for an average of about 15 IOPS per Windows 7 virtual PC, because, depending on the user, a Windows 7 desktop will generate 10 – 20 IOPS. Let’s tackle the IOPS issue first.

Thanks to Dan Feller of Citrix, we know how to calculate the “functional IOPS” of a given disk subsystem. Here are the significant factors that go into that formula:

  • A desktop Operating System – unlike a server Operating System – has a read/write ratio of roughly 80% writes and 20% reads.
  • A 15K SAS drive will support approximately 175 IOPS. The total “raw IOPS” of a disk array built from 15K SAS drives is simply 175 x the number of drives in the array.
  • A RAID 10 array, which probably offers the best balance of performance and reliability, has a “write penalty” of 2.

With that in mind, the formula is:

Functional IOPS=((Total Raw IOPS x Write %)/(RAID Penalty)) + (Total Raw IOPS x Read %)

If we put eight 15K SAS drives into a RAID 10 array, the formula becomes:

Raw IOPS = 175 x 8 = 1,400

Functional IOPS = ((1,400x.8)/2)+(1,400x.2) = 560 + 280 = 840

If we are assuming an average of 15 IOPS per Win7 virtual PC, this suggests that the array in question will support roughly 56 virtual PCs. So this array should be able to comfortably support our 50 Win7 virtual PCs, unless all 50 are assigned to power users.

That’s all well and good, but we haven’t talked yet about how much actual storage space this array needs. That depends on the size of our Win7 master image, how many different Win7 master images we’re going to be using, and whether we can use “linked clones” for VDI provisioning, in which case each virtual PC will consume an average of 15% of the size of the master, or whether we’re permanently assigning desktops to users, in which case each virtual PC will consume 100% of the size of the master. For the sake of this exercise, let’s assume we’re using linked clones, and that we have three different master images, each of which is 20 Gb in size. According to the Citrix best practice, we need to reserve 120 Gb for our master images (2 x master image size x number of master images). We then need to reserve 3 Gb per virtual PC (15% of 20 Gb), which totals another 150 Gb. The ViaB virtual appliance will require 70 Gb. We also need room for the hypervisor itself (unless we’re provisioning another set of disks just for that) and for swap file, transient activity, etc., so let’s throw in another 150 Gb. That’s 490 Gb minimum. So we need to use, at a minimum, 146 Gb drives in our array, which would give us 584 Gb in our RAID 10 array.

How about RAM? If we allow 1.5 Gb per Win7 desktop, then 50 virtual desktops will consume 75 Gb. We need at least 1 Gb for the ViaB appliance, at least 1 Gb for the hypervisor, plus some overhead for server operations, so let’s just call it 96 Gb.

We can handle 6 to 10 virtual desktops per CPU core – more if the cores are hyper-threaded – so we’re probably OK with a dual-proc, quad-core server.

Now, I don’t know about you, but if I’m going to put 50 users onto a single server, I’m going to want some redundancy. I will at least want hot-plug redundant power supplies, and hot-plug disk drives. Ideally, I would provision “N+1″ redundancy, i.e., I would have one more server in my ViaB array than I need to support my users. I’m also going to want a remote access card, and probably an uplift on the manufacturer’s Warranty so if it breaks, the manufacturer will come on site and fix it.

By now, you’ve probably figured out that we are not talking about a $4,000 server here. I priced out a Dell R710 – using their public-facing configuration and quoting tool – with the following configuration, and it came out to roughly $11,000:

  • Two Intel E5640 quad-core, hyper-threaded processors, 2.66 GHz
  • 96 Gb RAM
  • Eight 146 Gb, 15K SAS drives
  • PERC H700 controller with 512 Mb cache
  • Redundant hot-plug power supplies
  • iDRAC Enterprise remote access card
  • Warranty uplift to 3-year, 24×7, 4-hour response, on-site Warranty

(NOTE: This is a point-in-time price, and hardware prices are subject to change at any time.)

The ViaB licenses themselves will cost you $195 each. Be careful of the comparisons that show the price as $160 each. ViaB is unique among Citrix products in that the base cost of the license does not include the first year of Subscription Advantage – yet the purchase of that first year is required (although you don’t necessarily have to renew it in future years). That adds $35 each to the cost of the licenses.

Finally, If you don’t have Microsoft Software Assurance on your PC desktops – and my experience is that most SMBs do not – you need to factor in the Microsoft Virtual Desktop Access (VDA) license for every user. This license is only available as an annual subscription, and will cost you approximately $100/year.

So, your up-front acquisition cost for the system we’ve been discussing looks like this:

  • Dell R710 server – $11,000
  • 50 ViaB licenses @ $195 – $9,750
  • 50 Microsoft VDA licenses @ $100 – $5,000

Total aquisition cost: $25,750, or $515/user. Not bad.

But wait – if we’re going to compare this to the cost of buying new PC, shouldn’t we look at the cost of ViaB over the same period of time that we would expect that new PC to last? If we assume, like many companies do, that a PC has a useful life of about 3 years, then we should actually factor in another two years of VDA licenses, and two years of Subscription Advantage renewal for the ViaB licenses. That pushes the 3-year cost of the ViaB licenses to $13,250, and the cost of the VDA licenses to $15,000. So the total 3-year cost of our solution is $39,250, or $785/user.

If you want N+1 redundancy, you’re going to need to buy a second server. That would push the cost to $50,250, or $1,005/user.

What conclusions can we draw from all this? Well, first, that VDI-in-a-Box is not going to be significantly less expensive than buying new PCs, if you actually do it right. However, it is competitive with the price of new PCs, which is worth noting. As long as the price is comparable, which it is, we can then start talking about the business advantages of VDI, such as being able to remotely access your virtual desktop from anywhere, with just about any device, including iPad and Android tablets, and about the ongoing management advantages of having a single point of control over multiple desktops.

Also, as you scale up the environment, the incremental cost of that extra server that’s required for N+1 redundancy gets spread over more and more users, and becomes less significant. For example, if we’re building an infrastructure that will support 150 virtual desktops, we would need four servers. Total 3-year cost: $128,750, or $858.33/user for a robust, highly redundant virtual desktop infrastructure. In my opinion, that’s a pretty compelling price point, and you won’t be able to hit that price point with a 150-user XenDesktop deployment, because of the other server and storage infrastructure components that you need to build a complete solution. On the other hand, XenDesktop does include more functionality, like the rights to use XenApp for virtual application delivery, ability to stream a desktop OS to a blade PC or a desktop PC, rights to use XenClient for client-side virtualization, etc.

But if all you want is a VDI solution, ViaB is, in my opinion, the obvious choice. It’s clear that Citrix wants to position VDI-in-a-Box as the preferred VDI solution for SMBs, meaning anyone with 250 or fewer users…and there’s no reason why ViaB can’t scale much larger than that.

For more information on ViaB, check out this video from Citrix TV, then head on over to the Citrix TV site to view the entire ViaB series…

**** EDIT April 12, 2012 ****
You may already be aware of this, but Dell has announced a ViaB appliance that comes pre-configured, with both XenServer and the ViaB virtual appliance already installed. Oddly enough, even though Moose Logic is a Dell partner, I couldn’t get Dell to tell me what one would cost. Their answer was that I should call back when I had a specific customer need, and they would work up a specific configuration and quote it. I considered calling back with a fictitious customer requirement, but decided that I didn’t want to know badly enough to play that game.

They did, however, tell me what the basic server configuration was – and it was very close to the configuration I’ve outlined above: two X5675 processors, 96 Gb of RAM, eight 146 Gb drives in a RAID 10 array, Perc H700 array controller (don’t know how much cache, though), and iDRAC Enterprise remote access card. I do not know whether it has redundant power supplies (although I would certainly hope so), nor exactly what Warranty is included…perhaps that option is left up to the customer.

That gave me at least enough information to run a sanity check on the configuration. The array would provide 960 functional IOPS, which should be adequate for an 80 user system – which is how the appliance is advertised – depending, of course, on the percentage of power users. Also, the array should provide enough storage to handle the needs of most SMBs, unless they have an unusually large number of images to maintain.

One of my Citrix contacts recently told me that the Dell appliance was priced at $440/desktop for an 80 concurrent user configuration, which is very much in line with the cost per user in the post above, considering that $100 of my $515/user number was for the first year of Microsoft VDA licenses, which, to my knowledge, are not included with the Dell appliance.

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Beware of Vendor-Sponsored “Analysis” Reports

June 16th, 2011 | Posted by Sid Herron in Citrix | VDI | Virtualization | VMware | XenDesktop - (2 Comments)

Mark Twain allegedly came up with the famous line: "Figures don’t lie, but liars figure." That’s a good thing to keep in mind any time you’re looking through a report that was sponsored ("sponsored" = "paid for") by a vendor that concludes that their product is better than the other guy’s.

Maybe it is better than the other guy’s. But you might want to look closely at what was tested, how it was tested, and whether they were, shall we say, selective in the facts they present.

Case in point: The Tolly Group’s report, released May 27, comparing VMware View 4.6 Premier Edition to Citrix XenDesktop 5 Platinum edition. There are several interesting aspects to this report, which are dealt with in detail in Tal Klein’s blog over on the Citrix Community blog site. Here are a few of the more egregious items:

  • VMware View 4.6 Premier licensing costs less than XenDesktop 5 Platinum. Absolutely true, and absolutely irrelevant. That’s like pointing out that if you load every possible dealer option onto your new car, it’s going to cost more than the basic model. Thank you, Captain Obvious. If you want an "apples-to-apples" comparison, you need to compare VMware View to the XenDesktop VDI Edition. But wait, if you do that, XenDesktop is actually less expensive, and that would be an awkward point to publish in a paper that’s being paid for by VMware.
  • VMware’s PCoIP provides a more consistent multi-media experience than XenDesktop 5. (Over a LAN. Using a single thin client device that did not support any of the Citrix HDX media acceleration features.) Sorry, guys, but once again this is not an apples-to-apples comparison. And did they publish any results of testing across a WAN link? Nope…and for the same reason they didn’t use XenDesktop VDI Edition for their price comparison.
  • It’s easier to upgrade View 4.5 to View 4.6 than it is to upgrade XenDesktop 4 to XenDesktop 5. Once again, both true and irrelevant. It’s easier to give your kitchen a new coat of paint than it is to rip out the cabinets and completely remodel it. Anybody surprised by that? There are significant architectural changes from XenDesktop 4 to XenDesktop 5. It shouldn’t be surprising to anyone that this will involve more effort than a "dot release" upgrade.

I’ve always been skeptical of vendor-sponsored "analysis" reports, and, to be fair, Citrix has used the Tolly Group in the past for its own sponsored reports – but it seems to me that this one is just over the top. Apparently, former Gartner analyst Simon Bramfitt agrees. His pithy assessment of the report: "There are undiscovered tribes lost in the darkest parts of the Amazon jungle that would know exactly what to do if a vendor airdropped a pile of competitive marketing literature authored by the Tolly Group; send it back, and asked [sic] that it be re-printed on more absorbent paper."

What do you think?

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Thin Clients vs. Cheap PCs

June 1st, 2011 | Posted by Sid Herron in Licensing | Microsoft | VDI | Virtualization | Windows 7 - (3 Comments)

We have, for a long time, been fans of thin client devices. However, if you run the numbers, it turns out that thin-clients may not necessarily be the most cost-effective client devices for a VDI deployment.

Just before writing this post, I went to the Dell Web site and priced out a low-end Vostro Mini Tower system: 3.2 GHz Intel E5800 dual-core processor, 3 Gb RAM, 320 Gb disk drive, integrated Intel graphics, Windows 7 Professional 64-bit OS, 1 year next-business-day on-site service. Total price: $349.00.

When you buy a new PC with an OEM license of Windows on it, you have 90 days to add Microsoft Software Assurance to that PC. That will cost you $109.00 for two years of coverage. You’re now out of pocket $458.00. However, one of the benefits of Software Assurance is that you don’t need any other Microsoft license component to access a virtual desktop OS. You also have the rights, under SA, to install Windows Thin PC (WinTPC) on the system, which strips out a lot of non-essential stuff and allows you to administratively lock it down – think of WinTPC as Microsoft’s own tool kit for turning a PC into a thin client device.

Now consider the thin client option. A new Wyse Winterm built on Embedded Windows 7 carries an MSRP of $499. There are less expensive thin clients, but this one would be the closest to a Windows 7 PC in terms of the user experience (media redirection to a local Windows Media Player, Windows 7 user interface, etc.). However, having bought the thin client, you must now purchase a Microsoft Virtual Desktop Access (VDA) license to legally access your VDI environment. The VDA license is only available through the Open Value Subscription model, and will cost you $100/year forever. So your total cost over two years is $699 for the Wyse device vs. $458 for the Dell Vostro.

After the initial two year term, you’ll have to renew Software Assurance on the PC for another two years. That will continue to cost you roughly $54.50/year vs. $100/year to keep paying for that VDA license.

Arguably, the Wyse thin client is a better choice for some use cases. It will work better in a hostile environment – like a factory floor – because it has no fan to pull dust and debris into the case. In fact, it has no moving parts at all, and will likely last longer as a result…although PC hardware is pretty darned reliable these days, and at that price point, the low-end PC becomes every bit as disposable as a thin client device.

So, as much as we love our friends at Wyse, the bottom line is…well, it’s the bottom line. And if you’re looking at a significant VDI deployment, it might be worth running the numbers both ways before you decide for sure which way you’re going to go.

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IntelliCache and the IOPS Problem

May 20th, 2011 | Posted by Sid Herron in Best Practices | Citrix | Provisioning Services | VDI | Virtualization | VMware | XenDesktop - (0 Comments)

If you’ve been following this blog for any length of time, you know that we’ve written extensively about XenDesktop, and spent a lot of time on best practices and problems to avoid. And one of the biggest problems to avoid is poor storage design resulting in poor VDI performance.

In a nutshell, the problem is that a Windows desktop OS uses disk far differently than a Windows server OS. Thanks to the way Windows uses the swap file, disk writes outnumber disk reads by about 2 to 1. You can build your virtual desktop infrastructure on the latest and greatest server hardware, with tons of processing power and insanely huge amounts of RAM, but if all of the disk I/O for all of those virtual desktops is hitting your SAN, you’ve got a scalability problem on your hands.

Provisioning Services (“PVS”) can help to mitigate this in two ways (assuming for sake of argument that you’re provisioning multiple virtual systems from a common, read-only image): First, if you build your Provisioning Servers correctly, you should be able to serve up most of the OS read operations from the Provisioning Server’s own cache memory. Second, you can use the virtualization host’s local disk storage as the required “write cache” – because all of those write operations have to go somewhere while the virtual system is running.

But XenDesktop 5 introduced a new way to provision desktops called “Machine Creation Services” (“MCS”). We wrote about this in the April edition of our Moose Views newsletter, so if you’re not familiar with all the pros and cons of MCS vs. PVS, I’d encourage you to take a brief time out and read that article. Suffice it to say that, despite all the advantages of MCS, the biggest downside of using MCS to provision pooled desktops was that all of the IOPS hit your SAN storage, which limited the scalability of an MCS-provisioned VDI deployment.

But all of that just changed, with the release of XenDesktop 5 Service Pack 1, which was made available for download a week ago (May 13). With SP1, XenDesktop 5 is now able to take advantage of the “IntelliCache” feature that was introduced as part of XenServer v5.6 Service Pack 2. Using MCS with the combination of XenDesktop 5 SP1 and XenServer SP2…

  • The first time a virtual desktop is booted on a given XenServer, the boot image is cached on that XenServer’s local storage.
  • Subsequent virtual desktops booted on that same XenServer will boot and run from that locally cached image.
  • You can use the XenServer’s local storage for the write cache as well.

The bottom line is that you can move as much as 90% of the IOPS off of the SAN and onto local XenServer storage, removing nearly all of the scalability limitations from an MCS-provisioned environment.

With most of the IOPS for running VMs taking place on local storage, it’s pretty straightforward to figure out how many VMs you can expect to support on a given virtualization host. Dan Feller’s blog post does a great job of walking through the process of calculating the functional IOPS that your local XenServer storage repository should be able to support, and inferring from that number how many light, normal, or power users you should be able to support as a result.

This also means that using XenServer as the hypervisor for your XenDesktop 5 deployment is going to yield a significant performance advantage over any other hypervisor, unless or until the other guys come out with similar local caching features. So, if you’re a VMware shop, my advice is this: Go ahead and virtualize all of the supporting XenDesktop server components on your VSphere infrastructure. Run your XenDesktop 5 VMs on XenServer hosts, and just don’t tell anyone! If you’re asked, just say, “Oh, yeah, these are my XenDesktop host systems – they’re completely separate from our VSphere infrastructure, because we don’t need the (insert favorite VSphere feature) function for these systems.” Your infrastructure will run better, and no one will know but you…

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Machine Creation Services and KMS

March 30th, 2011 | Posted by Sid Herron in Citrix | Licensing | Microsoft | VDI | Virtualization | Windows 7 | XenDesktop - (0 Comments)

We’ve written extensively here about the challenges of using Citrix Provisioning Services to provision VMs that require key activation (i.e., Vista, Win7, and Server 2008/2008R2). We publicly rejoiced when the news broke that PVS v5.6, SP1, supported both KMS and MAK activation.

But now, with the advent of XenDesktop 5, there is a new way to provision desktops: Machine Creation Services (“MCS”). As a public service to those who follow this blog, I thought I’d share Citrix’s official statement regarding MCS and KMS activation:

MCS does not support or work with KMS based Microsoft Windows 7 activation by default, however the following workaround has been provided and will be supported by Citrix Support should an issue arise.

For details on the workaround, click through the link above to the KB article.

It does not appear that there is a workaround that will allow MCS to be used with MAK activation, and I saw a comment by a Citrix employee on a forum post that indicated that there were “no plans to support it in the near future.” So…MCS with KMS, yes; MCS with MAK, no.

Not having MAK support probably isn’t a big deal, since the main reason why you would go with MAK activation rather than KMS activation would be if you had fewer than 25 desktops to activate, and if you have fewer than 25 virtual desktops, you may as well just stick with 1-to-1 images instead of messing around with provisioning anyway. But we thought you should know.

You’re welcome.

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The Future Is Now

March 21st, 2011 | Posted by Sid Herron in Application streaming | Application Virtualization | Best Practices | Branch Repeater | Citrix | Mobile Computing | Remote Access | VDI | Virtualization | XenApp | XenClient | XenDesktop - (0 Comments)

I recently discovered a video on “Citrix TV” that does as good a job as I’ve ever seen in presenting the big picture of desktop and application virtualization using XenApp and XenDesktop (which, as we’ve said before, includes XenApp now). The entire video is just over 17 minutes long, which is longer than most videos we’ve posted here (I prefer to keep them under 5 minutes or so), but in that 17 minutes, you’re going to see:

  • How easy it is for a user to install the Citrix Receiver
  • Self-service application delivery
  • Smooth roaming (from a PC to a MacBook)
  • Application streaming for off-line use
  • A XenDesktop virtual desktop following the user from an HP Thin Client…
    • …to an iPad…
    • …as the iPad switches to 3G operation aboard a commuter train…
    • …to a Mac in the home office…
    • …to a Windows multi-touch PC in the kitchen…
    • …to an iPhone on the golf course.
  • And a demo of XenClient to wrap things up.

I remember, a few years ago, sitting through the keynote address at a Citrix conference and watching a similar video on where the technology was headed. But this isn’t smoke and mirrors, and it isn’t a presentation of some future, yet-to-be-released technology. All of this functionality is available now, and it’s all included in a single license model. The future is here. Now.

I think you’ll find that it’s 17 minutes that are well-spent:

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