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June 08, 2005

Diskeeper and email servers

Diskeeper works safely and effectively with email servers, whether they are Microsoft, Exchange,
Lotus, Domino, QUALCOMM, Eudora, or others. Diskeeper is uniquely designed to run in the background while these applications are operational and available to users. There is no need to stop or shutdown these applications or services to defragment.

There are two types of volume-centric fragmentation with which Diskeeper is immediately concerned: file fragmentation and free space fragmentation. File fragmentation concerns computer files that are not contiguous, but rather are broken into scattered parts. Free space fragmentation describes a condition in which unused space on a disk is scattered into many small parts rather than a small
number of larger spaces. File fragmentation causes problems with accessing data stored in computer files, while free space fragmentation causes problems creating new data files or extending (adding to) old ones.

Taken together, the two types of fragmentation are commonly referred to as disk or volume fragmentation.

Typically email application databases such as Microsoft Exchange and Lotus Domino are made up of a large container file that is preallocated in size at the point of creation. As the database increases beyond the initial assessment the file becomes fragmented.

Over a period of time, any popular email application server will also experience "internal" fragmentation of its database. This is where a record is removed, but the space it occupied within the database is still there and is either reused for a new record or must be skipped
over.

Let's say you have 250,000 records represented in an email server database. If an individual record (e.g. a deleted email) is removed, the location is simply marked as deleted. In the course of doing business hundreds, perhaps thousands of records are added and deleted. It doesn't take long for the internal organization of a database file, its indexes, and other related files to quickly become quite
disorganized. The speed of locating a particular record or segment of information is directly related to the amount time spent skipping over these holes or internal fragments.

The tools for Microsoft Exchange (ESE and EDB Utilities) deal with this internal record fragmentation by rearranging the internal records/indexes on the fly when possible, and at times requiring a whole new copy of the database to be created and each record copied to the new file. Even if this copy is done to a freshly formatted volume or a defragmented volume with a free space chunk large enough to contain the entire database, it's quite likely that this new copy will become fragmented. It is strongly recommended to run Diskeeper after performing email maintenance that rewrites the database. Otherwise, it is possible to actually worsen mail server performance due to additional required disk I/O.

The benefit of defragmenting an email server environment is no different than defragmenting any other system. It simply takes less time and system resources to access a contiguous file than one broken into many individual pieces. This improves not only response time but also reliability of the system. Thorough database maintenance requires a combination of Diskeeper (disk defragmentation), and the email server utilities (internal record/index defragmentation), to achieve optimum performance and response time.

Posted by Michael at 07:35 AM | Comments (0)