DOCUMENT:Q169199  31-OCT-1999  [exchange]
TITLE   :XADM: Purpose of Hierarch.dat in the DSADATA Directory
PRODUCT :Microsoft Exchange
PROD/VER:winnt:5.0,5.5
OPER/SYS:
KEYWORDS:exc5 exc55

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The information in this article applies to:

 - Microsoft Exchange Server, versions 5.0, 5.5 
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SUMMARY
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When the Microsoft Exchange directory service shuts down, it writes the basic
hierarchy structure to a file called Hierarch.dat in the Dsadata folder. This
file is used by the directory service on startup to quickly load the hierarchy
structure information and shorten startup time without having to read the entire
directory database again.

MORE INFORMATION
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This file can be safely deleted at any time. The only adverse effect is that the
directory service may take longer to start if the file is deleted while the
service is stopped.

The Hierarch.dat file is used to keep the number of objects in a container
between stops and starts of the directory service. Exchange Server writes it out
when shutting down, and reads it back in when starting up. Note that with
hierarchy calculation, finding out what containers there are is easy;
calculating the number of objects in a container is expensive. Normally, if you
press F5 in the Exchange Server Administrator program, you cause the hierarchy
to be recalculated. Shutting down the directory and deleting the Hierarch.dat
file also causes the hierarchy to be recalculated at start up, often leading to
long startup times for the directory.

Additional query words:

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Keywords          : exc5 exc55 
Technology        : kbExchangeSearch kbExchange500 kbExchange550 kbZNotKeyword2
Version           : winnt:5.0,5.5
Issue type        : kbinfo

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