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Microsoft KB Archive/169199

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Knowledge Base


XADM: Purpose of Hierarch.dat in the DSADATA Directory

Article ID: 169199

Article Last Modified on 10/28/2006



APPLIES TO

  • Microsoft Exchange Server 5.0 Standard Edition
  • Microsoft Exchange Server 5.5 Standard Edition



This article was previously published under Q169199

SUMMARY

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

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.

Keywords: kbinfo KB169199