Community

Desktop Virtualization: NetApp / Citrix continuing to lower the storage cost per desktop

By Abhinav Joshi, Sr. Product Manager, Desktop Virtualization, NetApp

For NetApp, 2013 has been another “Year of Virtual Desktop Infrastructure (VDI)” with deployments across all key verticals – Finance, Healthcare, Government, Education, etc. Citrix XenDesktop has been one of the key drivers for the accelerated adoption of Desktop Virtualization. Earlier this week, we announced another point in customer momentum with a major international airline using NetApp and Citrix solutions for their 11,000 desktops. This is part of the general shift to virtualization.

NetApp’s focus around offering a low cost, end to end storage solution to meet all the desktop data needs (OS, Apps, Profiles, and user data) has been a key driver for our success in desktop virtualization. Cost efficiency, performance acceleration, simplicity, intelligent backup/DR, and non-disruptive operations are the key elements of our solution.

Based on feedback from deployments for the last several years, we are continuing to develop/enhance the right set of partnerships, tools, reference architectures, deployment services, etc. to make your deployments successful. A recent example is our new Citrix XenDesktop on NetApp Clustered ONTAP solution. This solution offers a very compelling price/performance for real world desktop deployment; with the storage cost per desktop as low as $35/desktop. This compelling storage $/desktop number includes cost of NetApp hardware, software, installation, premium support & services.

Citrix Provisioning Server (PVS)  is a very popular XenDesktop deployment model worldwide, especially for large scale deployments. Citrix and NetApp have categorized the PVS based deployments into six scenarios based on the use cases that we commonly see deployed in customer environments today. The new Citrix XenDesktop on NetApp Clustered ONTAP Solution Guide (TR-4138) highlights the details on these deployment scenarios.

IOPS and capacity assumptions per desktop used to generate the sample storage array scalability guidelines for the NetApp FAS2240-2 HA and FAS3250HA storage platforms are also covered in detail in the NetApp TR-4138:

  • IOPS assumptions were determined based on detailed performance validation using LoginVSI heavy user workload scenario in conjunction with profile management tools such as the built-in Citrix User Profile Manager, redirecting user profile and folders to CIFS shares. Please see section in the new TR-4138 for details on the performance validation.
  • Capacity assumptions are based on what is typically observed in customer deployments.
  • Please note that LoginVSI does a great job at simulating users in a typical environment, and is commonly used by most of the vendors for developing Reference Architectures. However, the IOPS and capacity numbers for your deployment may vary based on the user profile and desktop applications in your environment. NetApp’s recommendation is to perform site assessments using tools like Liquidware Labs Stratusphere FIT to determine the actual performance and capacity requirements for your environment. NetApp and Liquidware Labs have partnered to #1) offer free site assessments for up to 500 users, and #2) deliver a custom NetApp report in Stratusphere FIT, helping simplify the sizing process.

Sample storage scalability guidelines for the entry level FAS2240-2 HA and mid-tier FAS3250HA storage systems for the six PVS based deployment scenarios are also highlighted in the TR-4138. The scalability guidelines range from a small 500 seats deployment to a large 4500 seats deployment. Using this cookie cutter approach, deployments can be easily scaled to 1000s of desktops. Similar scalability guidelines can be easily obtained for other FAS models by using the VDI module in the NetApp SPM sizing tool (accessible by NetApp field and partners).

These sample NetApp configurations offer a very compelling price/performance for the “all in one” NetApp storage solution to meet the data management needs of desktop OS, Apps, Profiles, and User Data from a single storage array. The storage cost per desktop for these sample configurations range from $35 to $92 (considering standard discounts).

Listed below are the design details of the persistent desktop deployment scenario offering a very compelling $35 storage cost per desktop (considering standard discounts). This storage configuration allows hosting 800 users in a 2 Rack Unit NetApp FAS2240-2 storage system. You can scale to 1000s of desktops at the same $35 storage cost per desktop by adding more 2U NetApp 2240-2 storage systems to the environment.

With all the storage $/desktop numbers floating around in the industry, its critical to understand the details on what’s included in these numbers.

The $35 storage cost per desktop includes:

  • NetApp Hardware: FAS2240-2 HA with 24 internal drives (600GB SAS, 10K RPM)
  • NetApp Software: NFS, CIFS, FC, iSCSI (storage protocols)
  • Support & Services: 36 months, 24/7, 4 hr parts replacement, and initial installation 

Here are the key design assumptions for this storage configuration. For details on this and the other configurations, please read section 12 in the NetApp TR-4138.

  • Personal Streamed Desktop (no roaming between desktops)          
  • Profile and folders hosted on Personal vDisk
  • User installed apps are persistent across reboot
  • Capacity requirements per VM:

·        PVS vDisk = 25GB (shared by 100s-1000s of users)

·        PVS write cache file = 2GB

·        Personal vDisk = 10GB

·        Personal vDisk dedupe savings assumption: 35% (savings might be higher or lower for your environment depending on the type and amount of data)

  • Performance requirements per VM:

·        PVS write cache file = 2 IOPS (95% writes) >>> lot of the IOPS moved to Personal vDisk

·        Personal vDisk = 6 IOPS (95% writes)

·        This system is capable of handling more than 10-15 storage IOPS per desktop (95% writes to storage array). PVS by design handles majority of the read IOPS from the host cache itself.

  • All VMs boot under 10 minutes.
  • LoginVSI application latency is within the acceptable limits (VSImax number less than 1,500).
  • NetApp storage controller utilization no more than 60% during steady state operations.
  • No performance degradation occurs when one NetApp controller fails.
  • 2GB storage per VM as VM memory vswap space on storage.

Please drop me a note at abhinavj@netapp.com if you are interested in discussing this further. 

In closing, if you are looking at storage for your Desktop Virtualization deployment, always look for a complete storage solution that can help you cost efficiently meet the data management needs for desktop OS, Applications, Profiles, and user data.

Comments
on ‎2013-05-22 04:46 PM

Have you considered running this with  a FAS2240-4  and  FlashPool   eg. 6X100GB SSD  and 18 X 3 TB SATA ?

Would you be able to host any more desktops on this solution ?

on ‎2013-05-22 11:59 PM

We have a problem with pvs vdisk on cifs share, when failover occur the stream services on pvs server hang and we must restart the service .

Do you have any solutions about this?

Citrix support said : no solutions about this :-(

NetApp Employee on ‎2013-05-23 12:40 AM

Richard - I would not recommend using a SATA Flash Pool for a PVS workload. The primary reason is that initially all writes will land on the spinning disks. Then only writes of type "random, overwrite" will be elevated to the SSD portion of the Flash Pool. See TR-3949, pages 51-52 for a performance comparison of SSD, SATA and FC/SAS disk (The document is for VMware View but the results comparison is still accurate for XenDesktop). Our testing has shown on a small scale there are not enough random overwrites to justify the cost of SSDs. As the workload gets larger (1500+ desktops) we saw between 10 and 20% increase in desktops by using Flash Pools (SSD+SAS). For a very detailed look at how Flash Pools work see TR-4070.

NetApp Employee on ‎2013-05-23 12:47 AM

Which version of PVS and Data ONTAP are you using? I would recommend checking out Dan Allen's blog, especially if you are utilizing a version of PVS prior to 6.1: http://blogs.citrix.com/2010/11/05/provisioning-services-and-cifs-stores-tuning-for-performance/

on ‎2013-05-23 04:55 AM

Windows server 2008r2 and pvs 6.1 Netapp Data ontap 8.1.2.

I have checked the post.

Our permormances are good, the issue is when FAS failover occur: we must restart the pvs servers.

I undestanding marketing word, but is incredible that this issue isn't track on any knowledgebase or citrix/ netapp documentations.

Any info are appreciated

on ‎2013-05-23 01:36 PM

Sorry I don't know very much about PVS   but  as the CIFS  protocol is "Stateful"   , it is  the client that is responsible for maintaining connections. it is typical for  CIFS clients to have to reconnect  to a NetApp Controller  after a fail over  event.  This is not a NetApp issue  this is how the CIFS protocol (SMB2)   behaves.

on ‎2013-05-24 09:44 AM

Ok, but this isn't track any where (netapp, citrix).

This configuration must be retired on all documentation, because isn't HA solution.

on ‎2013-05-24 10:56 AM

Hi Folks, Thanks for the great conversation. We are investigating the "vDisk and CIFS" issue highlighted here jointly with Citrix and will have an answer soon. The good news is that the $35/desktop number is still valid if you put the vDisk on LUNs backed by FC/iSCSI protocols.

on ‎2013-05-24 12:57 PM

Thanks a lots for your help.

I will wait official " response" about this issue and after i hope that all KB, TR will be fix accordingly.

Im not sure about "$ 35/desktop" with block disk, because i need other technologies (dfs, ecc) to replicate vdisk that require additional administrative effort and specific knowledge (storage admin/ sys admin)

Luca

on ‎2013-05-31 07:38 AM

@Luca Some clarification...the $35/desktop number includes the cost of storage hardware, software, support and services. Periodic vDisk updates should be factored in the overall desktop patch management cost that includes bunch of other things beyond just storage. There are several technologies available today that can make the process simpler e.g. dfs. NetApp FlexClone for cloning vDisks rapidly without consuming any storage.

on ‎2013-06-07 11:51 AM

Any news from Citrix?

Thanks

on ‎2013-12-17 11:00 PM

Thanks for pointing this risk outfit pbs design. I m keen to get answer on this configuration too

on ‎2014-02-17 02:24 PM

Great post! Been looking into these systems for my office recently. Thanks for the info!