XADM: Database Size After Offline Defrag Not Same as Total K

• Microsoft Exchange Server, versions 4.0, 5.0, 5.5

SYMPTOMS

When you perform an offline defragmentation on the Priv.edb or the Pub.edb, the size of your database after defragmentation may not coincide with the Total K of all items in Mailbox Resources or Public Folder Resources.

CAUSE

There are several reasons why the actual database size may not match the total size of Mailbox Resources. For example, if you add the Total K for each mailbox listed in Mailbox Resources, and it equals 1 GB, and then you run EDBUTIL /D on the Priv.edb, the resulting database size may be larger than 1 GB. This difference could range from a few megabytes to several gigabytes, depending on several factors on the Exchange Server computer, described in 1-4 below:

NOTE: In Microsoft Exchange versions 4.0 and 5.0, you use the EDBUTIL /D command to perform an offline defragmentation of a database. In Microsoft Exchange version 5.5, you use the ESEUTIL /D command to perform an offline defragmentation of a database.

1. The Priv.edb stores more than mailbox messages and folders. Inbox Rules, Views, and other items associated with the mailbox are stored here as well but are not represented in the Mailbox Resources page.

   store. A background cleanup process has to run first in order to fully
   commit the change. For more information about background cleanup, see
   the following article in the Microsoft Knowledge Base:

      ARTICLE-ID: Q159306
      TITLE     : XADM: IS Maintenance Tasks Not on IS Schedule.

   Running EDBUTIL /D; after this will give you a better count of what is
   actually in the database.

   to many mailboxes. For example, if you send a message to several
   recipients who reside on the same Exchange Server computer, the message
   is only stored once in the information store, and the recipients just
   receive a pointer to the message. If one recipient deletes the message
   from his or her mailbox, the message is not deleted from the information
   store, only the pointer to it. The message itself is not deleted until
   the last recipient deletes it. This also means that all messages
   associated with a user may not be removed from the Exchange Server
   computer when you move the user's mailbox to another Exchange Server
   computer. The message sent to several recipients will remain on the
   Exchange Server computer until all recipients of the message have been
   moved to another Exchange Server computer or they all delete their
   pointer.

   that requests new memory and requires that a new extent be allocated, is
   given a new extent of 16 pages (a page is 4 KB) -- regardless of the
   actual number of pages being requested (may be one page). This leads to
   a relatively sparse database structure. Therefore, it's generally true
   that the size of a Jet database will always be larger than the amount of
   data it contains.

Keywords          : XADM kbusage
Version           : WINDOWS:4.0,5.0,5.5
Platform          : WINDOWS
Issue type        : kbprb