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ACP Thin Client Newsletter Article |
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A common question from Thin Client users is this: "How many Thin Clients can I put on each Terminal Server?"
The answer varies depending on the particular situation. Therefore in this article I will give some general sizing guidelines, followed by a few specific examples.
The faster the better, of course. All modern computers have chips that are plenty fast. Dual processors are fine, but many industrial applications are single-threaded and the second processor is largely wasted in industrial settings. Nevertheless it will still be useful to offload system overhead.
Additional RAM is actually more important than a faster CPU. The memory needed is the RAM for the server + the RAM for each session, so how much you need depends on the size of the programs used by each user. With the low recent prices for memory this is not an area to skimp.
Microsoft says to allow 128 MB for the server and 8-12 MB for users running Office Suite. For instance, in a server with 2 GB of RAM you should reserve 128 MB for the server itself. This leaves 1.9 GB for the Thin Client sessions. Spread this among 100 users and everybody gets 19 MB.
Industrial applications typically use more memory - 64 MB for a small application, 96 MB for a medium, and 128 MB for a large application would not be abnormal. One of the leading HMI providers recommends 128 MB for each session. Once you allow 128 MB for the server:
Microsoft recommends that you use a file server or SQL server to store user data instead of storing the user-generated data on the terminal server hard drive. This means that any hard drive 10 GB or bigger should be fine. A lot of Thin Client systems use RAID1 mirroring or RAID5 to improve hard drive reliability.
100 users per terminal server is common when the applications are simple office applications, but 25 users is normally the limit of the number of sessions that people use for terminal servers in manufacturing. That is because the typical industrial application uses more resources and services.
Instead of putting lots of money into a powerful server (dual processor, fastest speed, RAID5) a better idea is to spend the same money on a couple mid-range servers (single CPU, 80% as fast) which will provide a backup server. This way a server failure will not bring down the clients - they will simply switch from the failed server to the backup. In fact, the best configuration will put 1/2 of the clients on one of the servers and 1/2 on the other. If one of the servers becomes unresponsive all of its clients simply hop over to the remaining machine.
For 25 Users
Two terminal servers with 3- 4 GB of RAM each. Boot 12 Thin Clients on one and 13 on the other. If one server goes down a single server could handle all 25 users.
For 100 Office Users
Two terminal servers with 4 GB of RAM each. Put 50 clients on one and 50 on the other. If one server goes down a single server will handle all 100 users.
For 100 Industrial Users
Five terminal servers with 4 GB of RAM in each server. Put 25 clients on four of them and have one sitting idle as a backup. If one server goes down the backup could handle its 25 users.
For 300 Office Users
Four terminal servers with 4 GB of RAM on each machine. Start with 100 on three and have one as a backup.
For 300 Industrial Users
Ten to Twelve terminal servers with 4 GB of RAM on each server. Distribute the Thin Clients among the servers and reserve 2 or 3 servers as backups.
NOTE: Once you get to 3 or 4 terminal servers use ACP's SmartSession to balance the load and make the backup server assignment easier.
For more information on ACP Industrial Thin Client computers, please visit our web site at http://www.thinmanager.com
For an archive of past newsletter articles, or to sign up for this monthly newsletter online, please visit our newsletter index at Past Articles
(c) Copyright 2006 Automation Control Products. All rights reserved. All product names contained herein are the trademarks of their respective holders.
