Memory use & management, in the Performance Tuning / Server Sizing forum on BrianMadden.com

We're in the process of finally migrating from NT 4 to AD. We've built two additional Citrix servers to use as our 50 active users move across.

As we've been migrating them, we've noticed that the new Citrix servers are using far more memory and it's unlikely that we'll be able to get 25 users on there. On the existing servers, we rarely go above 4GB at max load. On the new servers, we hit this limit at around 15 users.

We will be bringing a 3rd server online but I'm intruiged as to why memory use has gone up so much. The core changes are:

1. Running Windows 2003 server on core systems
2. Running under AD as opposed to NT 4 domain
3. Presentation Server 4.5 opposed to Presentation Server 3
4. IE7 as opposed to IE6 - my prime suspect
5. Running on ESX Server 3.5
6. Active Directory & Citrix PS 4.5 tools been used as opposed to NT 4 and PS 3.5

The ESX Server is a bit of an experiment that I'm not 100% convinced about and we may go back to running on the metal. Cloning Citrix servers using something like Acronis True Image (with universal restore option) might be a better solution longer term. However, it's there for now. Whilst I know that having ESX Server in there will be a hit on performance, it shouldn't be effecting memory use (4GB) should it?

We're on advanced licensing so don't have access to the Citrix memory optimisation technology. One of the two servers is currently running an evaluation copy of AppSense Performance Manager to see if that helps. By the end of the day, we'll have a good comparison. However, at £1000 a server, it's not a very attractive option right now. I'd prefer to spend 3 x £1000 on a new server... I know there are other features in there but I'd kind of expect the entire AppSense suite for £1000!!

I assume it's possible to upgrade our advanced licenses to enterprise to get the optimisation feature but I suppose the question is "Is it worth it?".

Cheers, Rob.

I also read somewhere that Windows itself does some kind of memory sharing itself, e.g. if 10 users load winword.exe, only one executable is stored in memory.

Is this correct? And if so, then DLL basing (or whatever it's called) is only going to be of limited use.

Cheers, Rob.

When you say "memory usage" can you be more specific? Are you using Taskman or Perfmon to gather your data?

What kind of apps are you using? Are the versions different? Lots of questions ;)

I would compare the data with the old boxes and look for mismatches.

i had the same problem 2 years ago when I did what you did.  You can either upgrade your licenses to enterprise and use the memory feature or you might be better off buying a 4th server??

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Well for starters, running Citrix on ESX or Xen or HyperV is not the issue so you can stop the talk about going back to metal as it won't change things. There are dozens of us running Citrix on one brand of hypervisor or another in more complex environments with no issues.

Try turning off the phishing for IE7 if its on and check for that blasted Window Search Indexer.

Start with the basic by running perfmon with no users and then load one at at time as see what happens.

How old is your new domain? Is DNS working properly? Are the Domain Controllers running ok? If an application has to wait for long responses from the network it might hold onto memory and not release. I have seen where name resolution latency led to sluggish apps on a server. It's good practice to check your DNS for all your apps and services anyways.