XenDesktop for the SMB/SME Webinar Questions and Answers – Part 1

For those of you who attended the XenDesktop design for small to medium business had many great questions. It has taken some time, but I’ve been able to provide answers to many of the submitted questions that we did not have time to answer during the webinar. First, some links for everyone:

  1. XenDesktop Design Handbook
  2. XenDesktop Design for SMB webinar

Now, onto the Q&A (note, this is part 1 of unknown number of parts. I had so many great questions that this will take some time).

Q: In XenDesktop is there a way to manually move the Master Farm Server to another to complete server maintenance

A: You don’t need to. If the XenDesktop farm master fails (or goes offline for maintenance), one of your other servers will take over that role.

Q: Is there any available documentation on a migration path/plan for going from XenDesktop 4 to XenDesktop 5

A: Not yet as the product isn’t out. There will be materials and recommendations and blogs talking about this in Q1/Q2 of 2011.

Q: If we do have the capacity to have the images on shared storage/SAN, is the performance going to be better than local?

A: It should, but it is tough to say. If the SAN is design right, it should be fully optimized and have plenty of caching capabilities and enough spindles to support the load. You could do the same for local storage, but again, you would need array controllers, spindles, etc. The only benefit you would get with local storage is that it is all local instead of going across the wire.

Q: Is it possible to stream remote desktops via broadband links to remote sites?

A: Anything is possible, but many things you don’t want to do. I assume when you say stream, you mean stream a desktop to an endpoint that is across a broadband connection using Provisioning services. The problem you will run into is the amount of data that is required. You need 200MB to boot, on broadband, this might take 1 minute. Plus, you need to be able to network boot. This is hard to do over your broadband connection. J Third, any time that the end point requires additional portions of the stream, it will take time to send it across the wire, which results in slow responses for the user. Best bet is to use a hosted solution (VM-Based or Shared) and the the HDX protocol go over the slow link.

Q: In this scenario are we using PVS HA? If so, best recommended way to sync vdisks

A: Yes, HA is planned for the environment. For smaller implementations where you only need 2 PVS servers, put the vDisk on local drives and either manually copy or have a script auto copy if one vDisk is updated. Keep it simple.

Q: Was Xenapp included in this Example for application management? Do you see VDI edition and building Apps into OS for SMB as an option?

A: For SMB, if you don’t already have XenApp, you might end up going with the VDI edition without XenApp. It is a decision you need to make. Do you want to manage more desktop images (becase the apps are in the vDisk image), or do you want to manage a XenApp infrastructure and have fewer desktop images. Most SMB implementations have few desktop images so installing the apps into the base desktop image simplifies the architecture. It does increase the number of images, but the number is manageable.

Q: Running two Web Interface VM’s makes sense for redundancy; but what are the type of failures that could fail one WI and not the other?

A: IIS service failure, disk space shortage, mis-typed configuration, etc. Many reason why one WI server would fail and not the other. Many times it is admin error, but you do get the occasional software glitch.

Q: we dont use provisioning servers?? we just connect the citrix clients through desktop delivery controller to the desktop VM’s is that an incorrect method?

A: That is an option and it does work. You essentially P2V your traditional desktop to a virtual desktop in the data center. The only thing is you have to manage the virtual desktops like you did in the physical world. PVS simply provides you with a single image management to help with operations.

Q: Does the provisionning server need to be physical as often recommended ?

A: No. It works virtual. However, you do have to look at performance. Many systems that stress a hardware component are questionable if they should be virtualized as the hypervisor will add overhead. The level of overhead is based on product, component, etc. You can virtualize PVS on a hypervisor, but you might not get bare-metal performance as PVS stresses the NIC.

Q: What is SRIOV?

A: SR-IOV allows the VM to bypass the hypervisor to get to the NIC. This helps overcome some of the overhead questions just mentioned. This blog is useful to see what I mean: http://community.citrix.com/display/ocb/2010/09/14/Citrix+Provisioning+Server+Gets+Virtual+with+SR-IOV

Q: do you need a separate image for each language or is it possible to do it with 1 image with language packs ?

A: Interesting question and I’ve never done it before, but if your base image contains the language packs, then you should be able to stream to multiple languages.

Q: What options are there for graphics intensive CAD workstation virtualisation ?

A: Streamed to the endpoint or Blade PCs. Both allow you to have full desktop power, plus allows for use of specialized hardware.

Q: For 500 users why not use VMs for the PVS servers (I know that Citrix doesn’t like it)?

A: With a physical PVS server, we estimate you will get 500 desktop streams per 1Gbps NIC. Unless you have SR-IOV on XenServer, you probably won’t get 500 streams per NIC. Plus, without SR-IOV, all of the NIC traffic has to go through the hypervisor, which can cause bottlenecks. Now if you virtualize, you will end up needing more virtual PVS servers than if you had physical PVS servers. Unfortunately, I don’t have stats on the virtual PVS.

Q: What about peak IOPS? logons and anti virus scans may push IOPS up to 150 for Windows 7?

A: AntiVirus must be configured so the impact isn’t as great. Logon storms are a big issue that we must determine how it will impact your overall storage design. I suggest you look at the XenDesktop Design Handbook as there is some info on AV design.

Q: What is the difference of using Hyper-V as solution for virtual desktop and using your product if we already have license with microsoft?

A: None. Hyper-V is a great option for XenDesktop. The rest of the architecture and recommendations should still be the same. We have a Hyper-V reference design for XenDesktop within the XenDesktop Design Handbook.

Q: I thought PVS and DDC only supports Windows 2003, is this still the case?

A: In XenDesktop 4, the DDC only supports Windows 2003. XenDesktop 5 the controller runs on Windows 2008. Provisioning Services runs on 2003 or 2008. 64 bit is recommended for PVS to get better caching capabilities.

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