Category Archives: Uncategorized

Virtual Desktop Training slidedeck

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For those of you who have attended our Virtual Desktop training and are waiting for the slidedecks I told you I would post here I haven’t forgot, I’m just waiting for our 3rd and final event to complete before I post them…otherwise it won’t be a surprise for the last group.  So keep checking and expect the slides after March 24.

Choosing a thin client OS for XenDesktop

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Feature Windows
XPe 		Linux Wyse ThinOS with TCX Comments
Flash Redirection Yes No No Wyse ThinOS with TCX supports flash acceleration which is not as desirable as flash redirection.
Multimedia Redirection Yes Yes Yes All clients support multimedia redirection for video codecs such as wmv, mpeg and avi.
USB Remoting Yes Yes Yes All clients support isochronous USB remoting such as Webcams and offer USB PDA sycronization.  Wyse ThinOS utilizes the TCX software.
VOIP – Optimized Speech codec Yes Yes No XPe and Linux client support the new Citrix speech codec.  Wyse ThinOS uses TCX Rich Sound which is less desirable.
WAN – Branch Repeater Client Yes No No Only XPe clients support the Branch Repeater Client, but the Linux client supports HDX IntelliCache WAN Optimization.   Wyse has a Virtual Desktop Accelerator for software WAN acceleration. 
HDX 3D Graphics Yes Yes No The Linux client does not support decoding of GPU-compressed data streams.

http://community.citrix.com/display/ocb/2010/03/01/Choosing+a+Thin+Client+OS+for+XenDesktop

Cannot Reattach XenServer Storage Repository

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I’ve recently encountered a situation when reattaching a forgotten (or otherwise unknown) LVMoHBA or LVMoISCSI SR where you are presented with a dialog which tells you that a previous SR has been found and that you need to select either to “Reattach” or to “Format” the device in order to proceed.

Here’s the rub (and the problem) – the buttons you need to press aren’t present.

This has occurred to me using XenCenter 5.5.2, on Windows 7. I expect it could also occur on Windows 2008, particularly on the R2 version. It might occur with other revs of XenCenter.

Here’s the work around – Run XenCenter 5.5.2 (or whatever is right for your environment) on Windows XP or Server 2003. The dialog will display properly and you will be able to complete the reattach process.

VMworld session TA3438 – Top 10 Performance improvements in vSphere 4

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http://vmjunkie.wordpress.com/2009/09/02/vmworld-session-ta3438-top-10-performance-improvements-in-vsphere-4/

 

  • IO overhead has been cut in half. Also, IO for a VM can execute on a different core than the VM Monitor is running on. This means a single CPU VM can actually use two CPUs.
  • The CPU scheduler is much better at scheduling SMP workloads. 4-way SMP VMs perform 20% petter, and 8-way is about 2x the performance of a 4-way with an Oracle OLTP workload, so performance scales well.
  • EPT improves performance a LOT. Turning it on also enables Large Pages by default (which can negatively affect TPS). Applications need to have Large Pages turned on, like SQL (which gains 7% performance)
  • Hardware iSCSI is 30% less overhead across the board, Software iSCSI is 30% better on reads, 60% better on writes!
  • Storage VMotion is significantly faster, because of block change tracking and no need to do a self-VMotion (Which also means it doesn’t need 2x RAM)
  • In vSphere performance between RDM and VMFS is less than 5%, and while this is the same as ESX3.5, performance of a VM on a VMFS volume where another operation (like a VM getting cloned) has improved.
  • Big improvement in VDI workloads – a boot storm of 512 VMs is five times faster in vSphere. 20 minutes reduced to 4.
  • PVSCSI does some very clever things like sharing the I/O queue depth with the underlying hypervisor, so you have one less queue.
  • vSphere TCP stack is improved (I know from other sessions they’re using the new tcpip2 stack end-to-end.
  • VMXNET3 gives big network I/O improvements, especially in Windows SMP VMs.
  • Network throughput scales much better, 80% performance improvement with 16 VMs running full blast.
  • VMotion 5x faster on active workloads, 2x faster at idle.
  • 350K IOPS per ESX Host, 120K IOPS per VM.

    • Windows 7 XP Mode RC Available

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    There is an article over at TechTree.com talks about the Windows XP Mode (XPM) RC which is now available for download. Good Stuff!

    http://www.techtree.com/India/News/Windows_XP_Mode_RC_for_Windows_7_Arrives/551-105212-580.html

    A similar article over at Virtualization Review – http://virtualizationreview.com/articles/2009/08/04/windows-xp-mode-rc-released.aspx