Net Work Structure

Morning Deemas,

Many of the hardware requirements you'd like depend on the load each server will face. With such a small network I would imagine that to be quite low.

A few more questions about the plan if possible.

The webserver is externally available?

Have you thought about a Firewall to protect your network?

Any ideas on how / if you want to backup any servers?

What specification is the IBM Server?

A lot of the set-up depends on what kind of budget you have to work with, in an ideal world it would be nice to run each server system on its own hardware, this however is rarely practical.

Active Directory

I would recommend that (as a minimum) two servers are configured as Domain Controllers. This makes recovering from a failed Domain Controller much much easier, preventing downtime. These servers can also take care of your DNS, WINS and Printer servers quite easily.

AD, WINS, DNS and Printering Services are all very low overhead, so these servers can be either relatively low spec seperate machines or combined with some of the other servers you have listed.

For naming your domain I personally would recommend using <domainname>.local for your internal network. This prevents problems with DNS.

Exchange Server & ISA Server

With the number of users you suggest there shouldn't be a problem loading these servers onto the same hardware. If you can I would avoid having anything else on this server.

SQL Server

Again, since you have a fairly low number of users I imagine the load on the SQL Server to be low, with that in mind I would combine this server with the secondary Domain Controller functions.

That gives:

First Domain Controller - Windows 2003 Server - Approx. 1.5GHz Pentium (III / IV). 512Mb RAM. 2 Hard Drives Mirrored RAID (if affordable).

Second Domain Controller - Windows 2003 Server - SQL Server - Approx. 2GHz Pentium (III / IV - Xeon if possible). 1Gb RAM. The hard drives depend on sever load and cost - but for low load systems I would go with 5 Hard Drives RAID 5 (optimum setup is 2 Mirrored for the Operating System, 2 Mirrored for the Transaction Logs, 3 RAID 5 for the Data).

Third (Domain Member) Server - Window 2003 Server - Exchange 2003 Server - ISA Server - Approx. 2GHz Pentium (III / IV - Xeon if possible). 1Gb RAM. Again dependant on cost 5 Drives in RAID 5 Config.

In all cases Hardware RAID if possible, that will be quite expensive, but something you'll really appreciate if you've ever had a hard drive fail.

Finally, if you have a public Web Server I would strongly advise it is put into a DMZ (De-Militarized Zone), this is a heavily firewalled area of the network seperate from the rest of your production network, that way if the Web Server is ever compromised it still won't be able to touch your production network.

Any thoughts so far?

Thanks for your reply Chris-Dent

Yes web server will be externaly available.

Firewall hardware ofcourse.

What do you mean by backup server.

Our IBM eserver configuration as follow:
PIII, 866MHz, 384MB RAM, Two 9.1GB Harddisk
------------------------------------------------------------------------------------------------
I Think This is what you suggest.

We need totaly 4 Server Machine (with the existing one)

1.  First Domain Controller  
2.  Second Domain Controller
3.  Domain Memeber Server
4.  Public Web Server (DMZ Zone)

All of the servers with Windows 2003 Server (4)

If i got it wrong please correct me. More over again if you can send me small diagram  will be more helpful.

thanks again

Hi again,

The Backup Server was mentioned to provide you with the ability to backup (probably to tape) the various components of your network including any data your users might have. If such a server is desirable I would upgrade the spec for the First server slightly and install it there (also perhaps making the First Server a File Server).

This will have to be a text diagram, I'm afraid I don't have access to the necessary ports (well FTP) to upload a picture to my website from here (so I hope it works - if not I'll post one when I get home).
 
                                            The Internet
                                                    |
                                               Firewall ----- Web Server (DMZ)
                                                    |
First Domain Controller  ---   Network Switch --- Second Domain Controller
(DNS / WINS / File / Print)       |            |                (SQL Server)
                                             |            |
       Third Server    _________|            |_____ (20 User Workstations)
(Exchange / ISA Server)

It seems a shame to waste that IBM Server you already have, so if you don't want to do anything else on the First Domain Controller (backup server etc) that's where I'd use it. Alternatively it can be another Backup Domain Controller.

What provision for Anti Virus do you have at the moment? With only 20 workstations it would be difficult to justify the cost of a centrally managed AV system.

I assume you would leave your ISP hosting the public DNS Settings (I would recommend that you do)?

With all of this server roles can be combined further at the expense of performance and fault tollerance. This is where something like Small Business Server comes in. While I'm not personally a big fan it will probably cost a lot less initially. My main problem with SBS comes with the eventual migration away from it.

If you're not already familiar SBS requires all servers (Exchange, SQL, ISA etc) to run on the same hardware. While SBS can have a second (backup) domain controller SBS is the only allowable primary (it cannot have the Operations Master Roles transferred). The current version of SBS is limited to 75 CALs.

It all really comes down to cost really.

For a start you can use the Microsoft Exchange server calculator, available as an Excel worksheet from here:

http://www.microsoft.com/exchange/techinfo/planning/2000/exchangecalculator.asp

It's not a good idea to have Exchange and Sql server on the same machine, both are processor intensive.

Yep I agree, SQL and Exchange on the same server should be avoided if at all possible.

Still i am looking for Hardware requirements too.

Thanks,