Optimum no of users per Citrix Server

Hi List,

Was hoping to get some inputs from the OneWorld Citrix Users out there. What is the optimum no of users to have on a single Citrix Box.

I have normally not seen more than 35 users on a single server. Any one running more than 35 users on one server. If yes could you please memtion your hardware specs and Citrix version

Thanks in Advance

We have dual 2.2ghz with 4 gigs of ram servers Citrix XP FR2. And I can stuff about 60 users on without any complaints of performance. But our users are not always fully active in the system and maybe half are data entry users. Our systems were heavily tuned on the windows end. Many of the ideas taken from this book Windows NT/2000 Thin Client Solutions: Implementing Terminal Services and Citrix MetaFrame ISBN: 1578702399 which is dated on the citrix information but is untouched by any other book on win2k termial service tuning.

The question of number of users on a citrix server these days really depend on how much memory you stuff into your box, not necessarily how much CPU power anymore with the latest CPU's. Just make sure you have dual processors in your box.

I always worked out that 2Gb of memory would give a MAXIMUM of 40 concurrent users (50Mb of memory being the minimal amount per user) - but you would likely need to have enough room for failover between multiple servers, hence the 30 users per terminal server. With 3Gb of memory, it can easily be seen that this can handle 60 users at the top end, but it would be adviseable to limit to 40 users or so.

With 4Gb of memory, it IS possible to achieve 80 users without so much of a major performance issue - but it would not be adviseable to size so many users for a citrix server, since it would be so highly utilized.

It is therefore adviseable to limit the memory to 3Gb on a dual processor box and keep the 35 users per box number as a good sizing guide - even though it is POSSIBLE to go over that sizing, the low cost of intel servers these days mean that you should keep the users performance as high as possible by ensuring as few users are sharing a device as possible.

We have Dell Dual P4 1.7s 4gB RAM and like to keep it around 30-40. One day some of the servers had gone down without us noticing, and to my disbelief there were 110 users on 1 Server. I did a run around to the users, and no one seemed to notice.

We also run a software called Appsense, which seems to make a difference (if we can run 110 users it must work)

Barry

I'm not sure that Appsense actually makes much of an affect on your server's scalability - just its reliability (of course, I might not be looking at the right appsense software - I was looking at www.appsense.com)

4Gb of Memory at 50Mb per user = 80 users. Not really far from your 110 users at all - and my guess is that there might have been some paging going on, but realistically the "quiet" users wouldn't have needed much resources and would likely have been paged off. Now, try 110 heads-down sales order entry users, and you would have seen an issue !

Jon,

Could you expand a little on the need for dual processors? Is there a specific problem with single processors in this area or is it just that they are more cost effective?

Thanks,

I always found 1 CPU insufficient even for a single user, leave alone 30 users on the same box. Personally, I like to have a dual-Zeon for a desktop, if I could... ;-)

Also, there's was an interesting problem with Windows on Intel (as opposed to Alpha), where it will not use any physical memory above 2-2.5 GB or so. The rest will stay unallocated, even if it badly needs to use more - it will be using Swap File instead... - haven't tested this for the latest SP's, but this held true before. Would be interested to hear otherwise...

It was alluded to in an earlier post but. . .
The kind of user will have a huge impact on how many per server you could comfortably accomodate. Heads-down 10-key types really put a load on the server per session. Then you have accountants that keep pushing grids into Excel, also resource hogs.
You will have other users that just do a lookup a few times during their shift, you could easily do 100+ of that type, since the only real load is the initial startup of EOne.
So it could look something like this:
Power-users 6 to 20
Ocasional users 50 to 100
"Your mileage may very" since it is more of a black art than science.

Thanks everyone for your valuable inputs.

Bob you make an interesting point that users doing exports to excel would consume a lot of resources for their session. I do envisage quite few users doing such operations. Apart from that a lot of UBE's would be run locally also.

Keeping this in mind and comments made by others , I think a Dual Processor , 4 GIG server should be able to easily cater to 40 users.....? What say the experts..

Thanks

ice_cube,

Here is another factor that the pundents did not mention, network. Most new servers are coming out with gigabit network cards. If you can get gigabit nics in all of your jde enterprise and terminal servers combined with a gigabit switch, now you're smokin! If you do stuff 4 gb of ram in the server, make sure that your OS is tuned to use the ram. Win2K is not tuned to use that much ram. I would go with Windows 2003 and Citrix Presentation server.

Gregg Larkin
JDE System Administrator (CNC) / North America
Praxair, Inc.

Yep about 30 is the confort zone. You are bound by the 2GB limiation os terminal srvices. Therefore, however many OneWorld sessions you can crowd into a 2GB address space will be your magic number. Some OneWorld applications have a larger foot print than other. Meaning a Sales Order Entry heavy environment will get less users in a 2GB address than another application would.