An Exchange Database contains multiple user mailboxes and there can be multiple databases in a single Exchange Server. Exchange Server is efficient enough to manage multiple databases. But as the size of the database increases, then the speed of Exchange decreases and creates performance-related issues. Some are described below:
Exchange administrators, sometimes, may not realize the growth of their Exchange databases. And this unusual growth often leads to mounting as well as inaccessibility issues. Luckily, there are many ways to reduce the size of database. Some are discussed here:
It is one of the most obvious methods to reduce the EDB file size effectively. Deleting unwanted data will create free space for adding new data. But make sure you don’t end up erasing important data accidentally. And surprisingly, even after deletion, you may not see any reduction in the size of the EDB file. But don’t worry—the space freed by deleting the data is there and Exchange will use it for adding new data (instead of increasing the databases size).
Offline defragmentation helps to reclaim the free space available (known as white space) in the Exchange database. This process compresses database, eradicates the blank and unused space, and reduces the database size. Thus, it effectively brings continuity in storage. And Eseutil is the Microsoft utility that helps in defragmentation. However, this process has the disadvantage that it is a slow process and can be performed only after dismounting the database (it means that all the mailboxes of the database will be unavailable for a considerable period of time).
You can get the amount of whitespace in a database by running the following cmdlets in Exchange Management Shell:
Before starting defragmentation, ensure that you have enough free space (110% of the size of the database) available on the server (or the network). Now stop the Exchange Information Store service, and follow the procedure below to perform the defragmentation:
Remember: The speed of Eseutil utility usually is 9 GB/hour and may vary according to the hardware and system environment.
Instead of performing defragmentation, many Exchange administrators create a new database and then move mailboxes from the older one to the new one (the older one can be deleted thereafter). It helps them achieve the same results as by the defragmentation. The advantage is that the mailbox down time is negligible. Also, it can be done from the Exchange interface (like Exchange Management Console).
Exchange administrators can back up the unused data in a different location and delete the same from the server to reduce the database size. For backup purposes, they can use the Windows Server Backup facility. And for exporting, they can try ExMerge or export cmdlets depending on the version of Exchange.
In Exchange 2010, use the following cmdlets to export mailboxes to a PST file:
Alternately, they can back up EDB files by exporting data to PST files using an efficient third-party tool like Kernel for Exchange Server. This Exchange Server Recovery tool will make the entire process effortless offering many flexible options.
To reduce Exchange database size, you have many options—delete unwanted data, perform defragmentation, move data to a new database, delete unused data after creating a backup, etc. And for backup purposes, you can try Windows backup utility, use inbuilt export utilities, or convert EDB to PST file using a third-party tool like Kernel for Exchange Server.