Capacity planning in Exchange 2007


We are currently running Exchange 2007 SP1 with an A/A/P SCC cluster on Windows 2008

The size of our organisation changes sometimes with new mergers and acquisitions. With Exchange 2003, the general policy was to just add the new users to the 2003 Exchange cluster without much thought regarding effect on the cluster.

I would like to change this attitude now :) Let's say that our cluster has 3000 users on each CMS. The CIO tells us that we've aquired a new company and that there will be 300 new mailboxes moving over. The mailboxes will actually be empty initially since the data will be held on a local PST, but we can expect them to grow to a couple of hundred MB each.

The mailboxes will be distributed equally across all the stores, however I want to know what effect this will have on the CMS's. Does anyone know any tools/calculators I can use to find out? Any other helpful points would be really appreciated.

Thanks in advance.
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Malli BoppeCommented:
On a monthely basis you need to start gathering the following information.
No of mailboxes
Size of databases
No of mails received and sent every day
Avg CPU and Memory usage
Disk space on servers.
Free space on the data bases
Malli BoppeCommented:
You migh also conside looking at archiving solution as well.
The Exchange team has an excellent excel file that calculates this:

And info about storage and estimating size is here:
kam_ukAuthor Commented:
Thanks xcomii, but those tools are for new installations of Exchange - are there any tools for existing versions of Exchange that are alreayd running but likely to have an influx of new users?
Well, if you have an estimate of your current storage need and you have some data about what the storage was historically, you could estimate future growth. However, the math is always complicated due to the fact that the numbers of mails and mail size could vary, it does tends to show that the mails are getting bigger and that max message size is increasing most places, which makes lazy users to put large files in attachments instead of sending trough other ways.

My personal opinion is to look in to the future and estimate what the storage requirements would be in 5 years, and then multiply it with 1.5. Other than that, just follow MS guidelines about how big each DB should be, you dont want to have them bigger than this due to the time of recovery if you ever need to do that.

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