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Vitaly91
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To Citrix or not to Citrix

Guys,

I know this is an old debate. Yet, I decided to bring it up yet again. Do you virtualize Citrix or do you not?

My thinking is that you do. A regular physical CTX box can host about 50-60 users (depending on apps it runs, etc.) In a virtual CTX box, you can host about 15 users. However, on a good ESX box you can easily run 7-8 CTX VMs. hence, you can host up to 120 users. Yes, it will take some performance hit. But I think benefits would out-weight negatives.

What do you think? Also, what would you consider a "good ESX box"? My thinking is that a good ESX box would be something like Sun's x4600. It can run up to 8 processors, 256Gb of RAM, etc.

I am looking forward to your opinions! Thank you in advance for your time!

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TomHowarth
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I to know Companies that have Virtualised their Citrix servers, but not all of them, only key app's that have low utilisation they have however had to seriously increase their farm size to compensate, thereby increasing licensing costs, this was offset by the purchase of DataCenter licencing and reduced power costs. but it is not all Roses in the garden, there are a lot of thorns. :smileygrin: Test, TEST and TEST again.

Tom Howarth VCP / VCAP / vExpert
VMware Communities User Moderator
Blog: http://www.planetvm.net
Contributing author on VMware vSphere and Virtual Infrastructure Security: Securing ESX and the Virtual Environment
Contributing author on VCP VMware Certified Professional on VSphere 4 Study Guide: Exam VCP-410

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TomHowarth
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I understand your logic, but it is flawed, the main issue with the virutalisation of a Citrix box is either Memory or CPU depending upon the applications (physical machine) in a virtual machine you are more likey to hit context switch issues. because your OS is waiting for a CPU to become available. if you SMP these servers you will only compond your problems.

Personally I would virtualise citrix servers only where

A: there is a business case for very high availbility (you would have a requirement for 5x9's and you can vMotion a running server to another host)

B: you have a server running a LOB for a limited number of users upto 15.

On your next point as ESX VI3 only supports 64Gb of memory due to it being a 32 bit OS, a server that can addess 256Gb is a little moot.

Regards

Tom

Tom Howarth VCP / VCAP / vExpert
VMware Communities User Moderator
Blog: http://www.planetvm.net
Contributing author on VMware vSphere and Virtual Infrastructure Security: Securing ESX and the Virtual Environment
Contributing author on VCP VMware Certified Professional on VSphere 4 Study Guide: Exam VCP-410
Vitaly91
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Tom,

Thank you for reply.

Yes, of course, at the present time, you can only load that ESX box with up to 64GB. I was kind of "peeking" into the future there. Smiley Happy

And yes, I agree that you take hits with performance. Yet, if your CTX servers run some specific, proprietary maybe, apps, why not virtualize them and save on space, operating costs, etc.?

I know there are companies out there that have done it and do not have any complains about performance of their CTX farms. So I think with proper sizing and planning, it can definitely be done. Maybe I am wrong here, but if you could "condense" a number physical boxes onto a couple of ESX boxes, use smaller footprint in the datacenter and make it highly available and easily scalable, why not do it?

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TomHowarth
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I to know Companies that have Virtualised their Citrix servers, but not all of them, only key app's that have low utilisation they have however had to seriously increase their farm size to compensate, thereby increasing licensing costs, this was offset by the purchase of DataCenter licencing and reduced power costs. but it is not all Roses in the garden, there are a lot of thorns. :smileygrin: Test, TEST and TEST again.

Tom Howarth VCP / VCAP / vExpert
VMware Communities User Moderator
Blog: http://www.planetvm.net
Contributing author on VMware vSphere and Virtual Infrastructure Security: Securing ESX and the Virtual Environment
Contributing author on VCP VMware Certified Professional on VSphere 4 Study Guide: Exam VCP-410
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Teiva
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yep, I agree with scaling out rather than scaling up. Citrix provides a Citrix Server Test Kit, I will be using during the pilot phase of our Citrix Consolidation phase to work out a just-milieu between connections and performance. From what I read, as you add more citrix servers to a host the performance degradation of your ESX host is predictable and linear as such. Of course heavyly used applications will be physicall isolated from the normal light application to give the majority of apps a better chance.

Citrix Server Test Kit explained here: http://support.citrix.com/article/CTX091649

As far as licencing is concern, from memory citrix licencing is per user connection rather than based on the number of installations, meaning if you have 120 users connecting over 8 to 20 citrix servers, the licence server only need 120 conneciton licences, therefore scaling out your farm will incure more maintenance and not more licences.

cheers

T

Teiva
TomHowarth
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As far as licencing is concern, from memory citrix licencing is per user connection rather than based on the number of installations, meaning if you have 120 users connecting over 8 to 20 citrix servers, the licence server only need 120 conneciton licences, therefore scaling out your farm will incure more maintenance and not more licences.

You are correct as the the concurrent licensing model of Presentation Server, however I was refering to Windows Server licensing which is one per server deployed. hence my comment on Datacenter license purchasing.

Kind Regards

Tom,

Tom Howarth VCP / VCAP / vExpert
VMware Communities User Moderator
Blog: http://www.planetvm.net
Contributing author on VMware vSphere and Virtual Infrastructure Security: Securing ESX and the Virtual Environment
Contributing author on VCP VMware Certified Professional on VSphere 4 Study Guide: Exam VCP-410
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Teiva
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fair call tom. Windows licences and potentially other applications licences, my bad!

Cheers

T

Teiva
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