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Q259851: XADM: Ramifications of Running ESEUTIL /P or EDBUTIL /D /R

Article: Q259851
Product(s): Microsoft Exchange
Version(s): 4.0,5.0,5.5
Operating System(s): 
Keyword(s): exc4 exc5 exc55
Last Modified: 25-JUL-2002

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The information in this article applies to:

- Microsoft Exchange Server, versions 4.0, 5.0, 5.5 
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SUMMARY
=======

A hard repair occurs when you run an eseutil /p or edbutil /d /r command against
an Exchange Server database file, such as the Priv.edb, Pub.edb, or Dir.edb
database. The repair goes through the database and checks and repairs critical
structures inside the database (such as system tables, attachment tables, and so
on) and checks for damaged pages in the databases.

If the repair encounters a page that is damaged (for example, an invalid checksum
caused by a modification to the page that was not preformed by Jet) it deletes
the page (-1018). When this happens, critical data may be lost after the repair
finishes. This data may be part of an e-mail message, a calendar appointment, a
note, an attachment, or in the worst-case scenario, part of a system table.

If that system table is the attachment table, every user on the server may lose
the attachments to their messages. This is only one possible scenario, but if
there are damaged pages in the database, data will be lost following a hard
repair.

IMPORTANT: It is always best to restore from a backup whenever possible.

If you restore from a backup, you ensure that you have a good, clean, stable,
database that will start and run on your server. In almost every circumstance,
it is faster and more reliable to restore from a backup than to perform a hard
repair on the database. This is because the repair runs at approximately 4 to 6
gigabytes (GB) per hour, and you must run the Isinteg process after the repair,
which runs at approximately 3 to 6 GB per hour. (These rates are average;
performance may vary depending on how many passes the repair has to make on your
database and the speed of the hardware.)

For example, if you use the fastest possible hardware setup, a 50-GB database
requires approximately 8 hours for repair and approximately 8 hours for the
Isinteg process, for a total of 16 hours. If you use a typical Wide
SCSI-connected digital linear tape (DLT) 35/70, which averages around 3
megabytes (MB) per second for restoration, the same database needs approximately
5 hours for restoration. That is a time savings of 11 hours. Extremely high
speed "snapshot" type backup systems, such as the system from EMC Corporation,
can restore a database of this size in a matter of minutes.

If you have no backup, and no other option but to run a hard repair on your
database, you must run the Isinteg utility after you run the hard repair. The
Isinteg utility fixes the logical problems that may arise when you run a hard
repair:

- For the Exchange Server 4.0 and 5.0 private information store, run the
  following command:

  isinteg -fix -pri

- For the Exchange Server 4.0 and 5.0 public information store, run the
  following command:

  isinteg -fix -pub

- For the Exchange Server 5.5 private information store, run the following
  command:

  isinteg -pri -fix -test alltests

- For the Exchange Server 5.5 public information store, run the following
  command:

  isinteg -pub -fix -test alltests

After you run the eseutil /p or edbutil /d /r command on the Priv.edb or Pub.edb
databases, the databases may exhibit the following symptoms:

- The information store either will not stop or stops responding.

- The information store stops accepting mail from the message transfer agent
  (MTA).

- E-mail remains in the Outboxes of the users.

- The Store.exe program runs with very high CPU use with no load on the server.

- The Store.exe program generates an access violation if there is a heavy load.

- Users cannot open e-mail attachments or e-mail messages.

After you run a hard repair on a database that has extensive damage, it is not
fit for production use. Only run a hard repair on your database as a last
resort; if possible, always restore from a backup.

If you have to run a hard repair on your production database, Microsoft
recommends that you move the data out of the repaired database to a new
database. Use one of the following two methods to move the data to a new
database:

- Using an Offline Defragmentation:

An offline defragmentation automatically creates a new database structure and
moves the existing data to that structure. For additional information, click the
article number below to view the article in the Microsoft Knowledge Base:

  Q192185 XADM: How to Defragment with the Eseutil Utility (Eseutil.exe)

- Using Exmerge:

The Exmerge utility can extract data from one database and place it in another
database previously created. For additional information, click the article
number below to view the article in the Microsoft Knowledge Base:

  Q259688 XADM: Steps for Using EXMERGE to extract Data from a damaged Database


MORE INFORMATION
================

To determine if a hard repair has been run against your database, dump the
header by using the following command line (the repair count will be zero if the
databases have not been repaired):

  eseutil /mh x:\exchsrvr\mdbdata\priv.edb |more

  eseutil /mh x:\exchsrvr\mdbdata\pub.edb |more

The following is a sample of a Priv.edb header:

  Microsoft(R) Windows NT(TM) Server Database Utilities
  Version 5.5
  Copyright (C) Microsoft Corporation 1991-1999. All Rights Reserved.

  Initiating FILE DUMP mode...
  Database: d:\exchsrvr\mdbdata\priv.edb

  Format ulMagic: 0x89abcdef
  Engine ulMagic: 0x89abcdef
  Format ulVersion: 0x620,2
  Engine ulVersion: 0x620,2
  DB Signature: Create time:4/5/2000 17:48:52 Rand:769046 Computer:
  cbDbPage: 4096
  dbtime: 556457
  State: Consistent
  Shadowed: Yes
  Last Objid: 184
  Scrub Dbtime: 0
  Scrub Date: 00/00/1900 00:00:00
  Repair Count: 1
  Repair Date: 2/20/2000 10:48:50

Additional query words: -1018 -1019

======================================================================
Keywords          : exc4 exc5 exc55 
Technology        : kbExchangeSearch kbExchange500 kbExchange550 kbExchange400 kbZNotKeyword2
Version           : :4.0,5.0,5.5
Issue type        : kbinfo

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