The
solution begins with the processor. You then need to determine memory
and hard disk needs per role. The interesting thing is that you might
already have a system in place that you can use for your Exchange
Server. You might not have to purchase anything.
The Processor
There
are two primary processor options for you to consider, and you might
have already guessed from looking at your server operating system
choices that they are both 64-bit processors.
You can use:
The
AMD Opteron or the Intel Xeon 64-bit processors are good choices, but
there might be others that work fine. Keep in mind that the Intel
Itanium (IA64) doesn’t work with Server 2003 64, so that would hinder
its use under those circumstances. Microsoft generally provides a list
of approved servers and processor types that you can check ahead of
time before you purchase to ensure you have compatibility with their
processor requirements.
You might consider a multicore processor for your Exchange server because tests have shown that there is a performance benefit.
The Memory
Several
theories regarding the memory needed depending on the server role
exist. With the Typical installation where you have all the roles on
one system, Microsoft recommends 2GB of RAM with 5MB added per user
(with the number of storage groups also considered, as you’ll soon see).
On
the Mailbox servers where you have your storage groups, you are wise to
include 2GB of RAM for every one to four groups. So, if you have five
to eight groups, you would make sure you have 4GB and so on.
In
terms of necessity, your Edge and HT servers do not require a
substantial amount of memory to perform well. Per processor core, 1GB
of memory with a 2GB minimum should suffice.
Disk Space
Installing
Exchange requires about 1.2GB of space. If you are working with Unified
Messaging language packs, you need to consider 500MB for each one. Make
sure you have 200MB on your system drive.
Note that all disk volumes for Exchange 2007 should be NTFS formatted.
Edge
Transport and HT servers store the message queue database and should
therefore have at least 500MB of free space for Exchange 2007 SP1.
Obviously,
your biggest disk sizes are needed on the servers that handle the mail
repositories—your Mailbox role. How does one determine the amount of
storage needed? Often it depends on the server configuration. Are you
using a form of fault tolerance or high availability? How many users
per mailbox? How many storage groups and databases and so forth?
Remember, you aren’t just looking at providing the proper capacity
here; you need to ensure performance is looked after, too.
There
is a requirements calculator located on the MS Exchange Team’s site
that is somewhat complicated but worth playing with, as shown in Figure 1. The site is located at: http://msexchangeteam.com/files/12/attachments/entry438481.aspx.
With
the Mailbox server, several considerations beyond the mailbox space
itself exist. Imagine that each user is allowed 1GB of space, and you
have 500 user mailboxes on that server. All 500 users might not have
mailboxes that are full, but you have to be prepared for that level of
mail. In addition to the database, there are transaction logs that are
growing each day for which you need to be prepared (and you might
prepare by moving those to other drives). You have deleted item and
deleted mailbox retention to think about. Full text indexing uses about
25 percent of the total size of the mailbox database! Translation: Lots
of disk space is a good thing on those mailbox servers. Faster,
reliable disk technologies are always the wiser choice when putting
together your Exchange servers.
