MS Exchange database files will simply multiply with the course of time but never shrink.
MS Exchange database is devised to run a defragmentation procedure by default once a day. This self defragmentation process helps the database to rearrange mailbox store and pub.edb file data in an efficient manner by truncating the unused storage memory. Exchange database performs online defragmentation automatically and this process is an integral part of database’s maintenance process.
The need of defragmentation might arise due to database size limitation reasons. Exchange server 2000 and the previous versions had a threshold limit of 16 GB. Then Microsoft introduced Exchange Server 2003 standard edition with an increased limit from 16 GB to 18 GB. However this can again be taken further to 75 GB with the help of registry key.
In Exchange Server 2007 and 2010, the size limit defined for an EDB database is sufficient (50GB). However, when the data size reaches the threshold limit, you cannot divert the mishap of corruption. This is when many question themselves- How to perform Exchange defrag?
The main purpose of online defragmentation is that it creates database space available by identifying and removing objects that are no longer in use by the user. This process offers more space to the user without actually performing any alteration in the file size of the Exchange database.
Despite the fact that online defragmentation offers some space, it is always suggested that you should perform Exchange database offline defragmentation to minimize the physical size of your EDB database.
Offline defragmentation can be performed with the use of ESEUTIL utility (by Microsoft) when all your mailbox stores and public folder stores are offline. You can use ESEUTIL tool to defragment the database pages by saving the old data in newly created database and discarding irrelevant and unused data pages.
Offline defragmentation is applicable in cases when you recently moved a number of users from server running Exchange 2000/2003. In this case, offline defragmentation reduces that size of the database by rearranging the data on Exchange Server database by abandoning the irrelevant or unused database pages.
Make sure that the time taken during the defragmentation process will always depend on the amount of free space in your database and the size of the transactions recorded in your database.
Offline defragmentation will help you create a new database by saving all the important data such as tables and records from old database. Copying the data also results in a lot of white space in your database and hence defragmentation is required to minimize disk space to meet the size of the database.
Thus, defragmenting Exchange database gives birth to a newly organized and compact EDB database file.