Category Archives: XenApp

PROOF[Video] – New XenDesktop and XenApp Storage Optimizations Does Improve the User Experience


I’ve written and seen numerous blogs/tweets about how great the new storage optimization feature is for XenApp and XenDesktop. I’ve read how this feature can reduce IOPS from an average of 15 IOPS per Windows 7 user down to 0.1 IOPS. I’ve read how this feature functions by creating a small RAM buffer within each VM. I’ve seen tweets showing crazy IOPS numbers on using standard, spinning disks.

In fact, I’ve done some of this analysis and was completely blown away by the results.

But who cares? Who cares if my IOPS are reduced by 99%?

Unfortunately, unless you are responsible for storage, you probably don’t care.  But what if this drastic reduction in IOPS had a direct impact on the user experience?  And from someone who uses VDI remotely 100% of the time, the user experience is what I really care about.

Let’s see what the new RAM Cache with Disk Overflow feature can do for the user experience…

What impresses me the most is that the workload used isn’t some crazy operation that a typical user wouldn’t really do.  You can easily see the improvement to the user experience with something as simple as browsing a few web pages.

And all of this is done

  • Without complex configurations
  • Without expensive SANs
  • Without SSDs
  • Without additional hardware
  • Without additional licenses
  • Without a learning curve

From the virtual mind of Virtual Feller

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Upgrading from XenApp 7.5 to XenApp 7.6


After delivering the XenApp 7.6 Upgrade webinar, I received a few questions asking if it is a good idea to upgrade from XenApp 7.5 to XenApp 7.6. My first reaction is, “Of course you should. Why wouldn’t you?”

But I’m a little biased J

You need to ask yourself if the new features within XenApp 7.6 are important enough to upgrade. Look at the following subset of features and determine if they are something that would be valuable for your users and admin:

  1. Unauthenticated Logons: This feature allows a user to access an application without being required to authenticate. This feature is mostly used in healthcare. If you need this, you must go to XenApp 7.6 feature
  2. Connection Leasing: You ever watch Star Trek and you hear the engineers talk about having secondary backups? A secondary backup won’t let your starship reach Warp 9, but it will keep your ship from exploding. That is essentially what connection leasing does for your XenApp site. Your first layer of backup is configuring your database to be highly available (mirroring, clustering or AlwaysOn). If that fails, you want to have a secondary backup, which is connection leasing. Another XenApp 7.6-only feature
  3. App Usage: Provides additional reporting capabilities for admins so they can see usage patterns for the applications. It’s good to know what your users are using.
  4. Fast App Access: “Patience you must have, my young padawan” is great if you are a Jedi. Unfortunately, my patience decreases waiting for my logon. A Windows logon includes a list of things (policies, logon scripts, drive mappings, etc.) that must execute before you can get to an application. Fast App Access essentially does all of the session creation processes before you request an app, greatly reducing logon times. In a production environment, the logon process that the user experiences is as follows:

    Take a look at the Session Prelaunch video to see how it is configured and functions.

What’s nice about being on XenApp 7.5 and upgrading to XenApp 7.6 is that the upgrade path is very easy. At a high-level, you essentially do the following:

You will notice that these are all upgrades. No need to rebuild. Of course, if you want more detail and guidance, then take a look at the following eDocs article.

The XenApp 7.5 to 7.6 upgrade is probably one of the smoothest upgrades I’ve ever done, and I’ve been upgrading since WinFrame.

 

From the virtual mind of Virtual Feller

The Latest XenApp 7.5 Read/Write Ratios


As technology changes, so too does a recommendation.

For years when you deployed XenApp servers with Provisioning Services, the storage Read:Write ratio would be 10:90. This is still the case in most scenarios. But in analyzing the latest data from the Citrix Solutions Lab, who were testing the “RAM Cache with Overflow to Disk” option, we encountered some results that will make us revisit some of our old recommendations.

  1. IOPS: For a medium workload on XenApp 7.5 on Hyper-V 2012R2, the average IOPS per user is 1, as explained in the previous blog.
  2. R:W Ratio: When using the new write cache option on Hyper-V 2012R2, the read:write ratio changes to 40:60. (Note: These numbers are taken at the physical host layer and not the VM layer)

Why is this? Why the change?

Think about what the RAM Cache with Disk Overflow does… It uses a section of allocated VM RAM to cache disk activity. As this cache fills up, it will start to move portions to disk. If you allocated enough RAM, you significantly reduce the number of IOPS (especially write IOPS). Look at the differences between PVS Disk and RAM Cache options

We’ve significantly reduced write activity because writes go to RAM. And whatever writes do make it to disk from the RAM Cache are bigger block sizes, thus also helping to reduce IOPS.

And finally, if you look at the disk idle time on the physical host, you can clearly see that the disks have a higher idle percentage when using the new RAM Cache with Disk Overflow option within PVS because we have less data going to the disk.

So far, the RAM Cache with Disk Overflow option is looking very promising. Soon, I’ll show you what it can do for Windows 7 workloads

For this setup, we used

  • LoginVSI 4.0 with a medium workload
  • Hyper-V 2012R2
  • XenApp 7.5 running on Windows Server 2012R2
  • 6 vCPU, 16GB RAM, 2 GB RAM Cache
  • 7 VMs per physical host

From the virtual mind of Virtual Feller

Latest updates to the Citrix Visio Stencils


As you saw in a previous blog, I created a new set of Visio stencils for XenApp 7.5 and XenDesktop 7.5 that included full diagrams within the stencil (I’m still impressed with this idea J)

Over the last few months, I’ve had to create a few more architecture diagrams and realized I needed a few more items. I’ve incorporated them into the latest stencil update. Recent additions include:

  • New virtual desktop model: DesktopPlayer
  • New user roles: User, Admin and Support
  • New hardware: SSD and HDD

Links to the latest stencils are:

From the virtual mind of Virtual Feller

The New XenApp – Reducing IOPS to 1


As we all know, IOPS are the bane of any application and virtualization project. If you don’t have enough, users will suffer. If you have too many, you probably spent too much money and your business will suffer. So we are always trying to find ways to more accurately estimate IOPS requirements as well as finding ways to reduce the overall number.

About 5 months ago, I blogged about IOPS for Application Delivery in XenDesktop 7.0. In the blog, I explained that for the XenApp workload, Machine Creation Services, when used in conjunction with Windows Server 2012 Hyper-V, required a significantly fewer number of IOPS than Provisioning Services. With the release of the 7.5 edition of XenApp and XenDesktop, I wanted to see what the latest numbers were on Windows Server 2012R2 Hyper-V while using the same LoginVSI medium workload. In addition, after reading Miguel Contreras’s blog on “Turbo Charging IOPS“, I wanted to see what impact the Provisioning Services “Ram Cache with Overflow to Disk” option would have on the results.

If you aren’t familiar with this caching option, it is fairly new and recently improved and I suggest you read Miguel’s blog “Turbo Charging IOPS“, to learn more. But essentially, we use RAM for the PVS write cache that will move portions to disk as RAM gets consumed, thus overcoming stability issues you would have with just a RAM Cache only option as the cache filled up. For this test, we allocated 2GB per XenApp VM. We only have 7 XenApp 7.5 VMs on the host, requiring 14GB total.

The results are impressive (at least to me they are).

042914_1620_1.png

On average, each XenApp 7.5 user requires 1 IOPS. If you want to be safe and go with the 95th Percentile, you have roughly 2 IOPS per user. We were able to achieve this without any complex configurations. We were able to achieve this without adding any new hardware to our servers. We were able to achieve this by literally flipping a switch within Provisioning Services. This is done with a little RAM and spinning disks only, no SSDs.

Some of you might also be wondering why MCS is lower than PVS (Disk Cache). This is one of the intrinsic benefits of MCS when deploying a Windows 2012R2 XenApp server on Windows Server 2012R2 Hyper-V. MCS is able to take advantage of the larger block sizes within the new .VHDX files, thus reducing IOPS requirements.

I keep hearing people say that Citrix needs to show some love to Provisioning Services as it is such a great product. I think the RAM Cache with Overflow to Disk helps.

Coming soon… VDI workloads as well as other hypervisors.

Virtual Feller’s virtual thoughts


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