Storage Groups, or, Keep Them Moving and Spread Them Out.

In a recent conversation with a colleague (James from VA in this case), he mentioned that there were a lot of folks who simply jammed all their users into one Storage Group in Exchange, even when they had the option to use multiple groups, and really should have.

Storage Groups are databases in Exchange Server.  They contain Information Stores and Log Files, and logically group together users and Public Folders that are related in some way.  There are a lot of different ways that you can choose to use allocate users to Storage Groups, but here are some of the more common methods:

1) Geography – Many organizations are centralizing Exchange servers to one or two datacenters, instead of putting a server at each location.  This saves money overall, allows for better message hygiene and, with the use of technologies like Outlook Anywhere, doesn’t alter the end-user experience to a any large degree.  Creating a Storage Group for each physical location allows you to better administer the Exchange system as a whole. If a new policy or procedure impacts only one office, you won’t be stuck combing through all the mailboxes and folders trying to find the users who are impacted by that policy. Just apply it to the Storage Group for that office and move on.

2) Department/Employment Level – This is a very popular method for splitting up users into Storage Groups, especially where there are a relatively small number of locations or other physical defining factors.  Many companies will define their Storage Groups by the departments that exist within the firm, mirroring their political structure into the messaging systems.  Sales, Support, Administration, Management and other logical groups can be translated into their own Storage Groups.  This has the dual benefit of not only allowing you to better control policies and procedures for each group, but also making it easy to put all managers into their own server which gets clustered, while the rest of the employees are on servers that will be restored from tape.  That’s just one example of the benefits of this segregation system for Storage Groups from the real world, so please don’t send hate mail. Of course, you can use a tool like Double-Take to give you even more options, but see the disclaimer at the bottom of the blog, as I’m far from unbiased on that topic.

4) Alphabetical – Where there may be only one or two locations for the business, or where everyone’s email is equal, then using something as simple as the alphabet can help figure out where to split out your Storage Groups.  A-M and N-Z or even 3 or 4 different breakouts can allow you to allocate your users across multiple Storage Groups without worrying about which users should go in which groups by other factors.

The reasons for splitting up Storage Groups go well beyond simple administrative tasks like policy and procedure enforcement. Storage groups can take an unmanageable situation, like 3000 users all in one gigantic glom, and make life easier to deal with by allowing you to manage smaller groups as required.  Database maintenance on a 500 user, 50GB Storage Group is a lot easier than database maintenance on a 3000 user, 1.2TB set of Stores.  It also means that the other 2500 users aren’t offline while you do that maintenance on the one Storage Group in question.

Physical limitations of Exchange could also force you to break things up into groups.  Granted, the built-in limit of 16TB per Storage Group (in Exchange 2007) is one most folks won’t ever hit without already breaking things out into multiple Storage Groups, but there are other size limitations.  Storage Groups must have their database files (.edb in 2003 and 2007, .stm in 2003 only) exist on a single logical volume.  This means that if you have 1TB of disk space, your Storage Group can’t grow past that point.  Multiple Storage Groups allows you to allocate your user data across multiple volumes, allowing easier growth and better storage management overall. This also leads to more spindles and read/write heads being used at once, which increases overall performance.

Even the Standard version of Exchange 2007 allows for up to 5 Storage Groups, so even smaller organizations can now split their users out across multiple Groups.  Exchange 2003 and earlier only supported one Storage Group, so if you’re on those versions, you will have to keep everyone together.  Otherwise, live by the simple mantra that more is better when it comes to the allocation of users to Storage Groups.