Microsoft recently introduced a feature pack that makes it easier to use Storage Server 2003 to manage storage for Microsoft Exchange servers. This offers several advantages, notably more efficient use of storage, centralized management of exchange databases and better protection of the data.
Each Exchange Server 2003 database (EDB) normally contains a MAPI (Mail API) files containing the message and property data for the e-mail messages. It also has a file containing the message data in MIME format and some log files. Any changes to the database, such as reading or deleting a message, is recorded in the current log file before being written to the database file itself.
Because the characteristics of the log and database files are so different, Microsoft has always recommended putting them on different physical disks. This is particularly true since the transaction log file is not only a good deal smaller than the database files, fast access to the transaction log file is the key to Exchange performance. One typical configuration is to use a mirrored volume for the transaction logs and a RAID 5 array for the data files.
The Exchange Server/Storage Server combination takes this one idea one step further. While the transaction logs are maintained on each Exchange Server, the databases are consolidated on a Storage Server. The separation can improve disk utilization, make it easier to manage Exchange storage resources and offer improved business continuance.
However, the gains aren't automatic. Whether the Exchange Server/Storage Server configuration is worthwhile has to be decided on a case-by-case basis. Among the factors to consider are the amount of message traffic, the storage requirements and the hardware available to support the servers. In general, the network connection and disk array are more limiting than available processor power. The deployment guide for the feature pack (available at the Microsoft Web site) offers specific guidance on analyzing a particular situation.
The exchange pack is designed to make the actual process of setting up the system as easy as possible. It is installed on a Storage Server 2003 and extends the interface to allow creating new shares for Exchange files. When the exchange pack is installed on the Exchange Server(s) it creates a wizard to help configure Exchange to store its files remotely, a feature to move the files and a mapping service to make the Storage Server shares available to the Exchange Server. The mapping service uses the Windows Distributed File System (DFS) to transparently redirect requests for Exchange data to the Storage Server. This lets the feature pack support Exchange backup programs.
Microsoft has a white paper titled "Managing Exchange Storage with the Windows Storage Server 2003 Feature Pack" available on its Web site. For more information:
About the author: Rick Cook has been writing about mass storage since the days when the term meant an 80 K floppy disk. The computers he learned on used ferrite cores and magnetic drums. For the last twenty years he has been a freelance writer specializing in storage and other computer issues.
This was first published in July 2004