Jul 15 2010

vSphere 4.1 – What has changed for VMware View?

VMware released this week vSphere 4.1, a dot release packed with new features and improvements on key performance areas. How do all these new features and performance improvements will affect VMware View VDI infrastructures? Off course everything helps on the overall, but I decided to list and comments on those few improvements that will provide best benefits for VDI.

Transparent Memory Compression (TMC) – this new feature is particularly important when running several desktop VM on a single host – does that resemble VDI? The feature is a new overcommit technique that compresses on the fly the virtual pages that should be otherwise swapped on disk. Each virtual machine has a compression cache where vSphere can store compressed pages of 2KB or smaller size. TMC is enabled by default on ESX/ESXi 4.1 hosts but the administrator can define the compression cache limits or disable TMC completely.

On VDI environments, often bound by memory the results in a performance regain of 15% when there’s a fair amount of memory over-commitment and a regain of 25% in case of heavy over-commitment.


Storage I/O Control – This feature provides quality-of-service capabilities for storage I/O in the form of I/O shares and limits that are enforced across all virtual machines accessing a datastore, regardless of which host they are running on.

VDI environments are highly IO intensive and disk contention will be quickly perceived by users when interacting with their desktops. The ability to monitor and take automated actions over VMs under disk contention will definitely help to maintain VDI infrastructures running smoothly.

Scalable vMotion – vSphere 4.1 supports up to 8 concurrent virtual machines live migrations. The engine has been significantly reworked to reach a throughput of 8GB/sec on a 10GbE link, 3 times the performance scored in version 4.0.

In VDI infrastructures where workloads can drastically change according to users interactions and activities, the ability to offload hosts quicker is crucial to maintain a stable environment for users.

Distributed Resource Scheduler (DPM) – DPM now has a set of scheduled tasks to help control it, turning it on and off at certain times of the day if you’d like. Disabling DPM will bring all the hosts out of standby, to help guarantee that no hosts get stuck in a useless state.

On VMware View infrastructures this feature improvement will provide flexibility to set hosts to power off at night hours and automatically bring them online prior to business hours. That’s GreenIT!

Memory footprint reduction– The hostd footprint and memory consumption (down by 40%) has been greatly reduced, speeding up some operations by a factor of 3x. Less memory overhead equals to more VDI VMs per host, or more memory available to give to users.

vCenter Server 4.1 – vCenter 4.1 also introduces better performance when used in conjunction with VMware View. The creation of new virtual desktops now is 60% faster and their power on timing is 3.4 times faster.

  • 3,000 virtual machines per cluster (compared to 1,280 in vSphere 4.0)
  • 1,000 hosts per vCenter Server (compared to 300)
  • 15,000 registered VMs per vCenter Server (compared to 4,500)
  • 10,000 concurrently powered-on VMs per vCenter Server (compared to 3,000)
  • 120 concurrent Virtual Infrastructure Clients per vCenter Server (compared to 30)
  • 500 hosts per virtual Datacenter object (compared to 100)
  • 5,000 virtual machines per virtual Datacenter object (compared to 2,500)

I am anxiously waiting for VMware announcements on View 4.5, and the support to more than 8 hosts per cluster when using View Composer. Unfortunately I have not inside track to know if this will change.

VMware vCenter Server Heartbeat 6.3 –View Composer v1.1 and v2.0 services can now be protected using vCenter Server Heartbeat.

Have I missed anything?


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  1. Joel

    Hi Andre.

    I think the new network load balancing policy will be very useful for VDI and of course the VAAI for cloning etc.

    // Joel

  2. Andre Leibovici

    If think you are talking about Load-Based Teaming and the dynamic adjustment of the teaming algorithm so that the load is always balanced across a team of physical adapters on a vNetwork Distributed Switch (enterprise plus license)

    You may be right but in my view most network traffic in a VDI environment is display protocol traffic (unless you have IP storage). How is this little traffic affected by dynamic adjustment, especially when most large deployments make use of 10G Ethernet interfaces? I don’t think much.

    VAAI is a different story and will help VDI infrastructures to implement dynamic growth based on usage. However, probably beneficial only for large environments.

  3. kopper

    so View manager 4 support vsphere 4.1 and vCenter 4.1?

    I was to install a VDI enviromento on ESX 4 update 1 and vCenter 4 update 1 thinking that View 4 was not supported on them….

  4. Andre Leibovici

    As today there is a known issue with View Composer being 32bit and vCenter 4.1 64bit. Therefore, linked cloning cannot be used. I believe VMWare is working to fix the issue not only for next release but also for the current View 4.

  5. kopper

    so I can safely use vCenter 4 update 2 and Vpshere 4 udpate 2 with View 4?

    thanks a lot

  6. Andrew Miller


    Yes, that’s what I’m currently doing….a bit of a catch 22 on the whole 64 bit thing until View 4.5 comes out.

  7. Andre Leibovici

    Yes you can, but be aware of an issue with VMware Tools U2 and PCoIP. See KB 1022830 for more details. I guess If you download ESX 4.0 U2 now the issue is already fixed but keep it in mind.

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