Q178021: XFOR: Many DAT Files in the Mtadata Directory

Article: Q178021
Product(s): Microsoft Exchange
Version(s): winnt:5.5
Operating System(s): 
Keyword(s): kbusage
Last Modified: 21-JUL-2000

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The information in this article applies to:

- Microsoft Exchange Server, version 5.5 
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SYMPTOMS
========

When you look in the Microsoft Exchange Server Mtadata directory, you may find a
large number of .dat files, for example, DB000123.DAT. Many of these files are
only 1 byte in size. This is also true, even if the Exchange Server message
transfer agent (MTA) does not have any messages in the queues held for delivery.

CAUSE
=====

This is by product design. In Microsoft Exchange Server 5.5, the MTA creates DAT
files for all messages. After the messages have been delivered, instead of
deleting the DAT files themselves, the data is deleted from the DAT files and
the files are reset to 1 byte. The DAT files can be reused for future messages.
This is done to enhance the performance of the MTA because creating and deleting
files is a time consuming process. The number of .dat files will reflect the
maximum number of messages in the queue at any one time.

Additional query words:

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Keywords          : kbusage 
Technology        : kbExchangeSearch kbExchange550 kbZNotKeyword2
Version           : winnt:5.5

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