Monday, February 28, 2011

How to get rid of Annoying Language Bar

Following language bar appear while accessing XenApp hosted application


This is kind of annoying but there are many way to get rid of it

1.  Following CTX explain how to get rid of it .

2.  Following Seamless flag also work like a charm

     Value: 0x40000
     Explanation: Starting with Citrix Presentation Server 4.5, when using a Language Bar (for example for IME) in an ICA Seamless session, minimizing the Language Bar displays an icon in the local Systray, as opposed to a minimized Window above the local Taskbar as seen in earlier Presentation Server versions. Set this flag to disable the Language Bar Systray Support in Presentation Server 4.5 or later only for troubleshooting purposes, as it will revert the behavior to prior versions, whereby once the Language Bar is minimized, the window cannot be restored.

3. But following ADM file control this language bar in best way using GPO.


Sunday, February 27, 2011

Performance VM Appliance for XenServer

Citrix has made available the XenServer Virtual Machine Performance Utility. The utility is provided as a virtual appliance running Debian Linux which you can run on XenServer 5.5 or 5.6 or 6.0 as well

Basically you start with configuring a webserver on the performance VM, providing it with the ip address and credentials of the Pool Master, so the VM can control it. From a web page running on the performance VM you can then start the utilities.

This VM does require PXE enabled DHCP but incase if you have static VLAN then manually IP the appliance


The following test utilities are provided:

Disk I/O performance utility – From XenCenter you create and attach thin provisioned Virtual Desktops from the storage repository to the resource pool. Through the webservice running on the performance VM an inflate for the thin provisioned VM will be initiated, and this process will be measured performance wise. The following disk I/Os will be measured: sequential read/writes and random read/writes with various specified block sizes. In order to access performance data, the tool needs access to Dom0.

Network I/O performance utility – Which uses a modified version of netperf. Netperf runs on the back end and provides end-to-end request/response round trip latency and TCP/UDP throughput tests. For this it needs a Linux VM or dom0 at a remote site on which netserver, the receiving part of netperf must be installed and running.



Once appliance downloaded and imported , it should be placed on DHCP network to get the IP address. Supply Dom0 password which is nothing but a password of XenServer host where VM is hosted.

Once it is on DHCP address , url can be access using http://<IP ADDRESS of VM>:8888 and then IP address can be changed if required



Before you start the VM you should add the HDD for which you need test the performance.



Similarly network I/O’s can also be measured.


How to Install XenServer 5.6 on HP Blade BL460 G7

Sunday, February 13, 2011

Network performance issue between XenServer and HP Blade

We came across very interesting performance issue on XenServer installed on HP Blade with Flex Fabric (Virtual Connect).

By default VC switch configured as default STP (Spanning Tree Protocol) . While uplinking virtual connect to the core switch , make sure that core switch port is configured for same STP . In our observation we found that core switch port were configured for MSPT (Multiple Spanning Tree Protocol) and link aggregation (LACP) were configured using 1GB port.

Due to STP configuration changes , convergence were talking some additional time. This results in  RTO and packet drop which was causing XenApp session freeze.

Conclusion : If LACP is used to get 4GB thoughput on uplink , make sure that there are no protocol mismatch. Default protocol on VC can be changed to match core switch protocol.

Friday, February 4, 2011

Deploying Citrix XenDesktop with FlexCast

When I was reading about FlexCast delivery for desktop deployment  , I had following question in my mind.

  • When you classify user to use XenApp hosted desktop?
  • When you classify user to use VM hosted desktop ?
  • How do you classify IOPs requirement for write cache ? Is it good idea to go with RAID 10 or RAID 5 ?

First let me explain what exactly is XenApp hosted desktop and VM hosted desktop is .

XenApp hosted Desktop (SHD) is : when virtual machine installed with XenApp is published and used as a desktop. Of course there are  tweaks to be done on XenApp installed on  windows 2008 server to have end user get a feel of desktop. Jo Harder  blog talks about it.

VM hosted Desktop (VHD)  is : When virtual machine installed/Streamed  with windows 7 or XP  are presented to the end user by the means of broker.

Now as we understood what exactly is SHD and VHD is , we will try to understand when we choose which model and why .

When we choose XenApp hosted Desktop (SHD):

While choosing XenApp hosted desktop (SHD) , we should remember that it scales better, cost less and is  a lot more proven in the enterprise (Compare to XD).  In certain case we can eliminate the need for shared storage. Are you are wondering how ? . When SHD model us used, more user can be accommodate on single machine.
But while selecting SHD model you may face challenges like
1.    Unique VLAN requirement: Suppose you are proposing SHD model and end user can not share VLAN . At that point of time you will have to choose VM per user group, though you can have 7 VLAN seen by single VM. 
2.    Application which is not compatible with TS/RDS.
3.    Users demand their own user space.
4.    User requires high quality video/audio. It is recommended to go with XD.
5.    Technical requirements dictate a XD based solution. Something like VPN client which can’t work on SHD model.

With XA environment, over committing CPU is not something which is recommended.  While choosing hardware, choose correct CPU model.  CPU with HT enabled will get you more logical CPU. For example if  it is a dual quadcore processer then logically you will get 16CPU  ,whereas non HT CPU model will get 8 CPU. This will make difference to the consolidation ratio.  HT enabled CPU will help you getting mode SHD.

With newer bread of CPU like Nehalem /Westmere , we can leverage HT for performance improvement as we as high consolidation ratio. Prior to Nehalem /Westmere it was advisable to stick with pCore to vCore mapping.  More logical CPU means better CPU:RAM ratio and better overall utilization of hardware.
It’s probably the best trade-off between CPU and memory and still keeps the number of VMs per hardware low.


While choosing VHD:

There is much option like SHD . With VHD , overcommitting of CPU is acceptable. For memory overcommit  DMC can be enabled which will help to squeeze a few more VM’s on a hardware. let’s say you get 100 XP VMs/blade and 50 Win7 VMs/blade.  HSD’s via XA can give you 4-8x the amount of users/box!!!  Even if we say 50 users/box on each of those XA VMs (very conservative), XA still could support 200 users/box where XD could support 50-100…that’s still 2-4x more scalable and it’s not uncommon in the real world to see a 3-4:1 ratio in the real world between XA:XD

Third question was what IOPs requirement for write cache.  Write cache is write intensive which is around 80:20 write:read IOPs. Since it’s write intensive , RAID1/10 would  recommended RAID model compare to RAID 5. Then question raised how do I size wirte cache drive. This would usually pagefile + writecache. It is advisable to place pagefile on a write cache drive for better performance and optimization. 
For example if XenApp VM has been assigned 6GB of virtual memory , configure page file of size 4GB and leave other 6GB for write cache. So you will size storage for 10GB writecache.  For VDI kind of environment, 5GB of writecache (Pagefile + writecache) drive is idle.

Size of the Writecache also depends on integration of profile solution and reboot cycle.

All feedback will be incorporated in next release

XenServer Configuration Maximums

I am trying to prepare config maximum for XenServer 5.6 . I will keep it updating till I test it .

For Virtual Machine


*A maximum of 8 VCPUs are supported by XenCenter.
†except for SLES 10 SP1 and RHEL 4.x, which support 3. RHEL 5.0/5.1/5.2 support 3, but can support 7 when the kernel is patched with the Citrix Tools for Virtual Machines. The same applies for Oracle and CentOS 5.0/5.1/5.2

image image

Some 32-bit Windows operating systems can support more than 4 GB of RAM through the use of a special
mode - physical address extension (PAE) mode. Administrators wishing to reconfigure a VM with greater
4 than 4 GB of RAM must use the xe CLI, and not XenCenter, as the CLI does not impose any upper bounds for

Source is following link

I will update this with XenServer config.