NIC is I/O and in a virtualized environment it has significant overhead in that a software layer is added to virtualize the NIC in a way that slows it down quite a bit. I would suggest, in general, that with 400 concurrent connections you have exceed what a VMWare based CSG can effectively handle, probably by quite a bit actually. The quick and easy proof is to spin up a CSG on a raw box and check the different in response times. The overhead in this case is not going to show in monitored utilization but more in the user experience of latency on the rich media stuff you are referring to. It is not a matter of utilization of VMWare resources as much as the fact that the virtualization I/O translation layer is simply too inefficient. Stay tuned- later this year Intel promises to have hardware NICS that are virtual machine aware…
The Netscaler is the product I am referring to. If you buy Netscaler Enterprise it includes a feature called Access Gateway. However, you can also buy the same product with only the gateway feature and it is called Access Gateway Enteprise Edition. It is very confusing, but in the end they are the same box with different software licenses loaded!!
Steve Greenberg
Thin Client Computing
34522 N. Scottsdale Rd D8453
Scottsdale, AZ 85266
(602) 432-8649
www.thinclient.net
steveg@thinclient.net
From: thin-bounce@freelists.org [mailto:thin-bounce@freelists.org] On Behalf Of Chris Grecsek
Sent: Friday, July 18, 2008 1:50 PM
To: 'thin@freelists.org'
Subject: [THIN] Re: Video Performance
Excellent feedback - thanks Steve! When you say VMware is bad with I/O do you mean disk or NIC or both? The perfmon counters we’re running on the VMs show very little utilization of disk or NIC so I guess we’ll just see how it goes.
We do have the WI and CSG on two separate VMs. We have about 400 concurrent connections on this WI/CSG set.
You also mentioned the Netscaler Access Gateway as a possible upgrade path from the WI/CSG. I’m doing some research but I must say, Citrix’s product naming bonanza makes me not 100% sure I’m looking at the correct product. I found information on the Access Gateway Enterprise Edition (AGEE) but is that a different product than the Netscaler Access Gateway? Was there a specific feature of the product that you think would be making the difference or is it just the fact that the device is designed to handle/manage that specific type of traffic/load?
From: thin-bounce@freelists.org [mailto:thin-bounce@freelists.org] On Behalf Of Steve Greenberg
Sent: Friday, July 18, 2008 1:07 PM
To: thin@freelists.org
Subject: [THIN] Re: Video Performance
Now that we know it is running on VMWare that could be the bottleneck right there- CSG is I/O intensive because of the nature of what it is doing as a proxy, this is the one area that hypervisor virtualization is still very weak at….
Steve Greenberg
Thin Client Computing
34522 N. Scottsdale Rd D8453
Scottsdale, AZ 85266
(602) 432-8649
www.thinclient.net
steveg@thinclient.net
From: thin-bounce@freelists.org [mailto:thin-bounce@freelists.org] On Behalf Of Chris Grecsek
Sent: Friday, July 18, 2008 11:21 AM
To: 'thin@freelists.org'
Subject: [THIN] Re: Video Performance
Hi Joe,
Thanks for the speedy response!
We’re not using any LBs – there are no network devices other than a standard PIX.
The WI and CSGs are both VMs on ESX 3.5. Based on your question I think we’ll setup a WI/CSG on a standalone server “just to see” even though we’re not seeing high utilization.
At this point we have not isolated the WI or CSG. We’re going to setup an additional site on the WI that will not use the CSG so that should achieve the isolation.
We’ve done quite a bit of testing with the speedscreen/multimedia stuff - I think we’ve tried every conceivable combination in the policies and farm settings . I believe the policies should apply the same whether we come in via the CSG/WI or the PN.
Image acceleration using lossy compression: enabled; compression level: do not use lossy compression; speedscreen progressive display:disabled
Speedscreen browser acceleration: off; speedscreen flash: enabled – all connections; speedscreen multimedia: enabled – buffer = 10.
Thanks again,
Chris
From: thin-bounce@freelists.org [mailto:thin-bounce@freelists.org] On Behalf Of Joe Shonk
Sent: Friday, July 18, 2008 10:35 AM
To: thin@freelists.org
Subject: [THIN] Re: Video Performance
It could be a couple of things…. Have you tried removing CSG from the equation and isolate if its WI or CSG? Is your CSG box running in a Virtual Machine? Do you have a LB in front of your WI and/or CSG box? How are you Applying the Ctx Policies for the SpeedScreen/multimedia.
Joe
From: thin-bounce@freelists.org [mailto:thin-bounce@freelists.org] On Behalf Of Chris Grecsek
Sent: Friday, July 18, 2008 10:24 AM
To: 'thin@freelists.org'
Subject: [THIN] Video Performance
We provide published desktops via Citrix/terminal services delivered via the internet. All users come in through the web interface/CSG via high speed, burstable (up to 100mb) connections. Most of the branch offices are <50 users so connectivity/maxxing out the pipe is not an issue. We don’t use any bandwidth restriction policies – users can use as much bandwidth as they’d like. We have bandwidth monitoring to look at all traffic and have our firewalls setup so that only Citrix traffic is using the burstable connection. Latency is sub 20ms and we have no packet loss.
Like everyone else using Citrix we’ve had challenges with video performance on the published desktop (Windows media player works great – Flash/other codecs, not so much). We had an interesting discovery today and I was curious if anyone could answer why/how this happens…when we connect to a published desktop via the WI/CSG (from one of our branch offices) video performance is bad. We ran a test today from within the datacenter where we connected to a published desktop, locally (from a laptop at the DC), using the Program Neighborhood as opposed to coming in over the WI/CSG and low and behold, video performance was excellent.
When we look at the amount of session bandwidth being used it’s nearly the same when coming in via the WI/CSG as it is when testing at the datacenter. So I guess the question is, is there something with the way the WI/CSG works that would be restricting/degrading the video performance (we ran performance counters on the WI/CSG and it doesn’t seem to be working very hard), is there a difference between using the Program Neighborhood verses the web client, etc.?
We’re on Citrix 4.5, latest rollups, latest version of the client, etc.
If anyone has any ideas, it would be much appreciated.
Thank you!
Chris
