Community Survey: Project VRC State of the VDI and SBC union 2015

Once in a while a request comes to my e-mail box with content to be included on my blog. This time it is Ruben Spruijt (@rspruijt) and Jeroen van de Kamp (@thejeroen) contacting about their project VRC ‘State of the VDI and SBC union’ community survey for this year. As the community is an important and often high quality source for opinions, input and discussions, I wanted to take part in reaching out to this community for participating on this year survey. The success of a survey will be determined on the amount of quality high responses, and that is just what the IT community brings more then often. Not that I have an awful lot of followers, but hey it just takes two to tango ;-).

This Project VRC what’s that about?

Project VRC is an independent R&D project. VRC stands for Virtual Reality Check. The R&D project was started in early 2009 and focuses on research in the desktop and application virtualization market. Several white papers are published about performance impact and best practices regarding different hypervisors, application virtualization solution, (Published) Desktop OS, infrastructure solutions and such for the VDI and Server Based computing environments. The previous published white papers can be downloaded from Of course you are also invited to take a look there. Previous survey white papers can be found there as well.

State of the VDI and SBC union survey 2015

In 2013 and 2014 Project VRC released the first iterations of community surveys about VDI and SBC environments. Over 1300 people participated so far. As times still continue on changing (and will be doing so on and on and on), and the more provided community knowledge as input for 2015 Project VRC the survey will get better and better. It needs your input (again if you already participated on previous versions). Who? Well everyone that is involved from strategy, designing, implementing and/or maintaining VDI or SBC environments can give helpful input in this survey. This survey probably will take no more than 10 minutes of your time. So what are you waiting for? A link probably, open or directly to the survey to fill out the Project Virtual Reality Check “State of the VDI and SBC Union 2015” survey.

This survey will be closed on February 15th of 2015.

– Have fun!


Keep on IO’in in the VDI world

I have already done some posting about analyzers, optimization and IO offloading ( and, but a question that rises often in VDI projects is what IO(PS) do we expect in what layers of the infrastructure and how can we measure them accordantly?

But first start at the start.

What kind of IO can we expect in VDI?

IO in the case of VDI, and other virtualization workloads, are mainly in the networking and storage. Networking IO is measured in the throughput of the network components and in the time a command takes in traveling through the components (up and downstream) measured in latency.

Storage IO is measured in the amount of operations (input output per second, IOPS), characteristics of the IO (sequential, random, read/write ratio), the time a command takes in traveling through the components (latency) and the throughput of the storage components.

Why is IO important in VDI?

Resources and IO these resources need is key in delivering a good desktop experience. It does not matter that the desktop is a physical or virtual desktop, it is a matter of ensuring that the desktop has sufficient hardware resources (the four horsemen CPU, memory, networking and storage) to run the OS and applications at the right time. Don’t have enough or slower then needed, the desktop experience will suffer immediately as will the users.
With physical desktops each of the resources are local to and dedicated for that desktop, with modern systems this is often not a problem, but here some of your user experience requirements are started. Most of the users are used to working with physical desktop environments and know what to expect in experience of those systems. They want the same or faster in VDI. With resources in VDI, there will be abstracting and pooling of those (hardware) resources. The resources are presented and pooled to the hypervisor host. For example the virtual hard drive is available on the hypervisor local or centralized storage. This storage is shared (or replicated) between hypervisor hosts. IO requirements and consequences of the IO load is spread across the virtual and facilitating resource (storage and network) infrastructures. In order to deliver a consistently high performance, virtual desktops require a constant access to preferably low latency and high throughput resource infrastructures.

What is normal IO in the VDI?

Normal? There is no normal. Every organization will have it’s own workload footprint, this is the case in server virtualization and this is also the case for virtual desktops. A Windows image will have a certain IO footprint that is more or less known out there (in averages), but depending on your build, sizing, own components and usage these differ. The IO footprint of a virtual desktop will be influenced by choices in your deployment, for example the optimization of your image, persistent or stateless, offloading of certain applications (like virus protection to the hypervisor), using application virtualization, optimized in IO characteristics (small random IO to large sequential IO) and de-duplication/compression throughout the infrastructure. With certain techniques you can get your IO down to and handled on the host.

How will you be able the know your specific IO? Well measure, test, baseline, report (or document) and repeat. Preferably start when planning (pilot or poc) for a VDI.
Sure, you can use one of the available calculators out there as a reference point (please do), but you still have to do some of the magic yourself.

How can we measure the IO of the VDI?

It is important here to know what kind of components are in your infrastructure and how to measure the metrics of these components.

Start from within your guest as there the user will feel it’s pain, oh wait….will get his warp speed desktop experience.

Tools as a complete solution:

  • vCenter Operations (VCOPS) and for VDI specifically, VCOPS for Horizon view. Complements the vCenter / ESXi monitoring and metrics already in place with excellent views and reporting states of your environment.
  • EdgeSight and Desktop Director for XenDesktop VDI.
  • XenServer monitoring, depending on your version you will possibly need to add a Performance Monitoring Enhancement pack.
  • Planning tools like the VMware View Planner (, or analyzer tools like the VMware fling vBenchmark ( / IO Analyzer ( or for Citrix the XenServer PerformanceVM.
  • Login VSI an industry standard load testing tool for virtualized desktop environments. Login VSI can be used to test the performance and scalability of every Windows based virtual desktop solution. Can be used for VDI Horizon View, XenDesktop as well as heterogeneous solutions where SBC or RDS are in place. ( there is going to be a blog post on this subject a little later on).
  • Nagios / Cacti and the like. You will have to add your counters and checks to the configuration, which can be a little gruesome if you don’t have any experience. But these are excellent products to have your whole infrastructure monitored with all sorts of counters and have a chains with parents and child objects in there.

Tools at the layers:

This really depends on the solution in place. Know your infrastructure and how traffic flows is key here. The monitoring needs to be planned so that you get your counters in the same time window and with the same metrics. Get the disk and network counters from the guest OS itself thoughout the infrastructure. Keep an eye on the CPU and memory on all layers, and check for paging/swapping. Averages on layer x and downstream in real time can be a bother. Also like written in a previous post, time (and time zone) needs to be set correctly and synchronized with the same source.

But to give some pointers

  • Perfmon / Resource monitor.
  • iostat/vmstat/top and other Linux tools.
  • Hypervisor monitoring, like from vSphere webclient /vCenter/ESXi host or XenCenter.
  • Esxtop / XenTop / vscsistats. See some standards in my post (
  • Networking SNMP tools, or the own supplied tools.
  • Storage SNMP tools, or the own supplied tools. When you have switches and controllers in your storage infrastructure monitor them all the way.
  • Benchmarking tools like IOMeter, IOzone, Passmark or specific to a kind of workload (be ware, there are a lot out there).

– Happy IO’in in the VDI world (and cue Neil Young)

Atlantis ILIO – RAM Based storage matched for VDI

I personally am very fond of solutions that handle IO close to the source and therefor give more performance to your virtual machine workload and minimize (or preferably skip) the storage footprint downstream. I previously written a blog post about sollutions you can use at the host. One of these solutions is Atlantis ILIO.
As the company I currently work for (Qwise – is also a partner for consulting on and delivering Atlantis ILIO solutions, I thought one plus one is… three. 

If you’re not familiar with Atlantis ILIO, it works with running an Atlantis appliance (VSA) on each of your hypervisor hosts (dedicated for VDI for example) and presenting a NFS or iSCSI data store that all the VMs on that host use. For this data store it uses a configured part of the hosts RAM to handle all reads and writes directly from this hosts RAM (that is when you let the VM deploy here and you have reserved this RAM for this kind of usage). The IO traffic is first analyzed by Atlantis to reduce the amount of IO, then the data is de-duplicated and compressed before being written to server RAM. When needed Atlantis ILIO converts small random IO blocks into larger blocks of sequential IO before sending to storage, increasing storage and desktop performance. This is the IO Blender Effect.
The OS footprint is minimized to a rather small one in RAM, numbers of 90% percent can be reached depending on the type of workload. Any data that will be written to the external storage (outside of RAM) also undergoes write coalescing before it is written. 

Since Atlantis will only store each data block once, regardless of how many VMs on that host use that block, you can run dozens or hundreds of VMs of just a tiny amount of memory.

And what does RAM gives? A warp speed user experience and faster deployment.

Atlantis ILIO can be used for stateless VDI (completely in RAM), persistent VDI (out of server memory or shared storage backed), XenApp and can also be used with virtual server infrastructures.

Atlantis ILIO Architecture


Like written before Atlantis ILIO is deployed as an appliance on each host or on a host that serves a complete rack. This appliance is an Atlantis ILIO (or ILIO for short) controller or instance. The Atlantis ILIO appliance uses a defined part of the host it’s RAM to present a NFS or iSCSI datastore via the hypervisor. Here you can place the VD’s, XenApp or other needed to accelerate VM’s. ILIO sits in the IO stream of your VM, hypervisor and storage. You need the correct Atlantis product to use the optimized features for the wanted solution workload, currently VDI and XenApp. Keep an eye out for other servers solutions, there bound to come out this half of 2014.
In above model the hypervisor is VMware vSphere with a stateless VDI deployment, but this can be Citrix XenServer or Microsoft Hyper-V as Atlantis supports these also. The Atlantis presented storage can be easily used to accelerate PVS or MCS for using XenDesktop provisioning. Or in combination with some form of local or shared storage for persistent desktops unique user data.

Atlantis ILIO Management Center.

The Atlantis ILIO Management Center will setup, discover and manage one or more Atlantis ILIO instances. The ILIO Center is a virtual appliance that is registered with a VMware vCenter cluster. Once ILIO Center is registered with a vCenter, ILIO Center can discover Atlantis ILIO instances that are in the same vCenter management cluster and selectively install a Management Agent on Atlantis ILIO instances. If additional vCenter clusters with Atlantis ILIO instances exist, then an ILIO Center virtual machine can be created and registered for each cluster.
The ILIO center can be used for provisioning of ILIO instances, monitoring and alerting, maintenance (patching and updates) and for (probably the most importing part) reporting of the status of the ILIO proces and handled IO offload (for example what amount of blocks is de-duped). The ILIO center can also be used to fast clone a VD image. This clones full desktop VM’s in as little as 5 seconds without network or storage traffic.

Hosts and High Availability (mainly for persistent deployments)

Atlantis supports creating a synchronous FT cluster of Atlantis ILIO virtual machines on different hosts to provide resiliency and “zero downtime” during hardware failures. Atlantis supports using HA across multiple hosts or automatically restarting virtual machines on the same host. 

A host that is offering resources to a specific workload, for example the VD’s, this is called a session host. This session host can use local or share storage for it’s unique data storage. With shared storage when a failure happens you can use the hypervisor HA (together with DRS VM rule to keep appliance and VD’s together). When using local storage in vSphere this is not an option as HA requires a form of shared storage. For this you can use ILIO clustering with replication.

With the availability of unique local host data a replication and a standby host come into the picture.

In a Atlantis ILIO persistent VD solution, a replication host is a centrally placed Atlantis ILIO instance that maintains the master copy of each user’s unique data. The desktop reads and writes its IO on the RAM of the session host. The session host (after handling the IO) then replicates any unique compressed data over to the replication host. This replication is called Fast Replication. The replication is handled over the internal out-of-band Atlantis ILIO network. The replication host is shared storage backed where the unique user data is written. There is also a standby host that is a standby for the replication host. This standby host has the same access to shared storage location as the replication host. In case the replication host fails the standby host takes over and has access to the same unique user data on the share storage. Keep in mind that, depending upon your workload, between 5 and 8 session hosts can share a single replication host. 
Disk-backed configurations that leverage external shared storage do not need a Replication Host as ILIO Fast Replication mirrors the desktop data directly from the external storage to this shared storage

For non persistent stateless VD’s the data stays purely in RAM. VMware Horizon View or Citrix XenDesktop will notice that the VD’s are down when the hosts fails, and will make new VD’s available at an other host. Users will temporarily experience a disconnect but their workspaces will reconnect when available again.


With interesting RAM pricing and reducing infrastructure complexity Atlantis ILIO is the perfect solution to use in (re)building VD infrastructure with already in place solutions or solution components. You can provision lighting fast VD’s and engage your workforce to warp speed productivity) with a user cost around 150-200 euro. You can session hunderd of VD’s with just a small amount of configured RAM on one host. Next to this you will have a much smaller unique IO data footprint on your shared storage. No need to go with expensive accelarated storage infrastructure controllers. You can easily go with a cheaper SAN/NAS/JBOD or a No SAN solution.

– Happy Atlantis ILIO’ing!