I have always found that one of the biggest challenges in managing an Exchange environment is capacity planning.
Capacity planning is a critical task because of the limits imposed both by Exchange Server and by your server's hardware. For example, in Exchange Server 2003 Standard Edition, an Exchange database has a maximum size of 16 GB.
On one hand, this 16 GB limit could be thought of as a safety net. If a database can never grow beyond 16 GB in size, then theoretically as long as you set aside 16 GB of space you never have to worry about your server running out of disk space due to explosive database growth.
Unfortunately, this theory doesn't hold water for a couple of reasons. First, even if your databases never grow beyond 16 GB, your transaction logs could easily grow to the point that they run the server low on disk space. Another reason why the 16 GB limit isn't really a safety net is because you can have more than one Exchange database per server.
My point is that the 16 GB limit truly is a limit and not just a safety factor. You need to plan accordingly so you don't exceed this limit.
Because I own a business, I retain a lot of e-mail messages in an effort to keep Uncle Sam happy. I also keep most of my business related e-mails just in case I am ever sued or in case I ever have to refer to an e-mail conversation that I had with someone (which with my memory happens pretty often).
Because there are so many messages that I have to keep, I normally archive the messages from each year into a PST file. That keeps the messages from past years off of my server. Although this technique has worked well for me in the past, there are a few problems with it.
First of all, PST archival must be done on a per user basis. In a large organization, it just isn't practical to try to archive everyone's mail once a year. Another problem is that a PST file has a 2 GB limit. If the file exceeds 2 GB in size, it becomes corrupted and for all practical purposes, unusable.
In the past, the 2 GB limit has never been a problem. However, I have yet to archive my messages from 2003. My server's information store size at the moment is about 4.5 GB. That may not sound like a lot, but it's way too much information for a single PST file. My wife and I are the only ones with mailboxes on the server, and there are only 14 months worth of archives in the database. At the current rate of growth, the mailbox store will hit the 16 GB mark in a couple of years.
Obviously, you need a plan for long-term data storage. One thing that you can do is to upgrade to Exchange Server 2003 Enterprise Edition. The Enterprise Edition's maximum database size is limited only by your hardware. The theoretical maximum database size for Exchange Server 2003 is 16 TB, which is more than adequate for most organizations.
In a big organization, though, even a 16 TB limit may eventually be reached in a few years. Because of this, you need to come up with some sort of e-mail retention policy. I know that some organizations have policies in which any message in a user's mailbox that is more than 30 days old is automatically deleted. This policy is great for reducing the database size, because it forces users to deal with the messages that are in their mailboxes rather than just letting them sit there eating up space.
However, such a policy causes other problems. Friends that have tried implementing similar policies have told me that users are constantly asking them to restore old messages that the server has deleted. Another common technique for controlling the size of the Exchange database is to set quotas on the size of individual mailboxes. Quotas get the job done, but they often force users to delete messages which might be needed later.
While requiring users to delete old e-mail messages might not seem like such a big deal, you have to stop and think about the Sarbanes-Oxley legislation. This set of legislation defines document retention guidelines for publicly and privately held companies. There can be some stiff criminal penalties for managers of companies if specific types of documents are not retained for the required period of time, and e-mail messages often fall within the guidelines of documents that must be retained.
If you are running out of space, but need to keep certain messages on file, you might try implementing an archival solution such as EAS from Navistor. EAS archives important messages to its own database, thus freeing up the Exchange Server. Messages within the archives are fully searchable, but all of the standard Exchange permissions apply, so there is no danger of someone searching for a message that doesn't belong to them. Best of all, EAS uses a compression system that requires a lot less disk space than would be required if the messages were stored within an Exchange database.
Brien M. Posey, MCSE, is a Microsoft Most Valuable Professional for his work with Windows 2000 Server and IIS. Brien has served as the CIO for a nationwide chain of hospitals and was once in charge of IT security for Fort Knox. As a freelance technical writer he has written for Microsoft, CNET, ZDNet, Tech Target, MSD2D, Relevant Technologies, and numerous other technology companies. You can visit Brien's personal Web sites at http://www.brienposey.com and http://www.relevanttechnologies.com.
