Exchange Disaster Recovery
in a Nutshell

  

General Information

 

Copyright: Marco Mels,

Comments to: marcoedwin@hotmail.com

Version: 3.0

 

 

This document describes several scenarios regarding Exchange. Please note that this document does not describe how to plan the backup and restore procedure. The information has not been reviewed by Microsoft and does not intend to speak on behalf of Microsoft. Distribute this document freely; note that the author cannot give you warranties or assurance regarding errors or anything else. You can use the tools that are discussed in this document at your own risk.

 

Please note that Microsoft recommends customers to call Microsoft Product Support Service in case of an Exchange disaster and recovery scenario. Running the tools that are discussed in this document is at your own risk. This document is only intended to help an administrator to understand the concept as a whole. If you are not an expert, then this is a checklist of what you already should know before administering an Exchange environment. If you are not very comfortable with the implications of this document, you should contact Microsoft Product Support Service for online assistance.

 

General Information.. 1

1     General information.. 3
1.1      Software agents. 3
1.2      Solving the actual cause is more important.. 3
1.3      Hardware and software requirements. 3

2     Exchange and the tools to use. 4
2.1      Getting Exchange up and running again and minimizing downtime. 4
2.2      General information on the tools. 4
2.3      Most important tools for a disaster recovery scenario.. 4

3     Three things to take into consideration.. 5
3.1      Exchange Optimizer. 5
3.2      Exchange databases and log files. 5

4     Tools and parameters and general precaution.. 6
4.1      General precaution: Disk Space. 6
4.2      What is needed for a successful Exchange recovery.. 6
4.3      The parameters. 6
4.3.1       Checking the state of each database. 6
4.3.2       Making the databases consistent: caution. 7

5     Scenario: “Moving Exchange to another machine”. 9
5.1      General information.. 9
5.1.1       Pre-installation requirements. 9
5.1.2       Reinstall Exchange, SAM database and directory store. 9

5.2      The procedure itself. 9

 

1        General information

 

1.1      Software agents

 

In case of a disaster and recovery scenario, you should always make sure there are no software agents running in the background. Meaning: you should verify that you, as the administrator, remove the virus scanner, or any other software agent that runs in the background, from the system first. This is really important, because the point is that the mail server should be up and running again and problems with locked files or any other problem should be avoided before taking any action.

 

1.2      Solving the actual cause is more important

 

Secondly there is the event log file. Event log files are extremely important in case of disaster recovery. Looking at the actual cause of the disaster and even better, solving the original problem first, is the best course of action. In this case you can set the Exchange services to manual and after you have rebooted the Exchange server, check what events are popping up.

 

1.3      Hardware and software requirements

 

Another thing is that Exchange consumes loads of RAM (Random Access Memory). Make sure you have enough of it or at least that you run your Exchange Server configuration with the minimum required.  Configure the paging file to at least total RAM * 1.5 or total RAM * 2 for the minimum size. The maximum size of the paging file should be set to a higher size.

 

2        Exchange and the tools to use

 

2.1      Getting Exchange up and running again and minimizing downtime

 

In case of a disaster recovery scenario, the administrator has to decide if he wants to restore from latest backup or “try” to get the databases back to a consistent state. First of all, the administrator has to verify that there is a recent backup available. If there isn’t, there are not many options left. However, if there is one, the administrator has to verify if the backup is recent and if the backup is consistent.

 

In general there are two options here:

1.        Restore from previous backup.

2.        Run some integrity tools on the Exchange databases.

2.2      General information on the tools

 

With Exchange 4.0 and 5.x, there are some tools you can use to get the system up and running again. You can find these tools in the following folder:

 

                X:\EXCHSRVR\BIN

 

In case of disaster recovery scenario, please make sure you understand the several risks of using these tools. You can find more information on the Internet, for example:

1.        http://www.microsoft.com/exchange/DeployAdmin/DeployAdmin.htm.

2.        http://www.microsoft.com/technet/support/default.htm.

 

2.3      Most important tools for a disaster recovery scenario

 

The tools that make the administrator’s live more easily:

1.        ISINTEG.EXE (located in the \EXCHSRVR\BIN folder).

2.        ESETUIL.EXE or EDBUTIL.EXE.EXE (located in the\SYSTEM32 folder).

 

3        Three things to take into consideration

 

3.1      Exchange Optimizer

 

After you have successfully installed Exchange, Exchange asks the administrator if he would like to run the Exchange Optimizer. This is a really cool tool that separates the Exchange databases and Exchange log files from each other. Of course the tool does more than that, however the Exchange Optimizer will not be discussed in this document. In case of disaster recovery, you should really make sure you understand the way Microsoft Exchange stores the data.

 

Let me summarize the most important folders.

1.        First of all, there are the program files. Exchange program files are located in the following folder: \EXCHSRVR\BIN.

2.        The information store (PRIV.EDB/PUB.EDB and some other files) is located in the following folder: \EXCHSRVR\MDBDATA.

3.        The directory store (DIR.EDB and some other files) is located in the following folder: \EXCHSRVR\DSADATA.

 

However, remember that after you have run the Exchange Optimizer, there is not just one \MDBDATA and \DSADATA folder. Exchange stores the data and the log files at separate locations. The trick is that you should backup all the folders named \MDBDATA and all the folders named \DSADATA.

 

3.2      Exchange databases and log files

 

Generally, if you understand that log files and Exchange databases can be corrupt, you understand the most important things of disaster recovery. That means that, after you have scanned the Exchange databases for corruption and after that you have noticed that there is no corruption involved, there still might be a possibility that you cannot start up one or all of the Exchange services.

4        Tools and parameters and general precaution

 

4.1      General precaution: Disk Space

 

Exchange 4.0, 5.0 and 5.5
--------------------------------
Exchange will need 125 of the size of the PRIV.EDB and PUB.EDB files in free disk space. The question here is if you already freed up hard disk space. During disaster recovery, this is really important.

4.2      What is needed for a successful Exchange recovery

 

Before running any tools on the Exchange databases, you should make sure you have a consistent and recent backup of the following files:

1.        PRIV.EDB (mail messages).

2.        PUB.EDB (public folder hierarchy).

3.        DIR.EDB (objects within Exchange).

 

Best practice is that you stop all the Exchange services and make a file copy of the following folders:

 

EXCHSRVR\MDBDATA.

EXCHSRVR\DSADATA

 

NOTE: make sure you have a copy of all the \EXCHSRVR\MDBDATA and \EXCHSRVR\DSADATA folders. For more information, see the Online Help within Exchange Administrator and search for “Exchange Optimizer”. Check all your hard drives or partitions. There might be a case that there is more than one \MDBDATA and \DSADATA folder. You need to back up all of these folders first.

 

4.3      The parameters

4.3.1      Checking the state of each database

 

Exchange 4.0 and 5.0
--------------------
EDBUTIL.EXE /mh x:\exchsrvr\mdbdata\PRIV.EDB > privmh.txt.
EDBUTIL.EXE /mh x:\exchsrvr\mdbdata\PUB.EDB > pubmh.txt.
EDBUTIL.EXE /mh x:\exchsrvr\dsadata\DIR.EDB > dirmh.txt.

Exchange 5.5
--------------------
ESEUTIL.EXE /mh x:\exchsrvr\mdbdata\PRIV.EDB > privmh.txt.
ESEUTIL.EXE /mh x:\exchsrvr\mdbdata\PUB.EDB > pubmh.txt.
ESEUTIL.EXE /mh x:\exchsrvr\dsadata\DIR.EDB > dirmh.txt.

NOTE: if you run this tool from the \EXCHSRVR\BIN folder, the text file will be placed in the same folder. You can view the output with a standard editor such as NOTEPAD.EXE or EDIT.COM. Running the tool again, replaces the original text file. It does not append the new data to the text file. There is no need to run the tools in the order provided in this document.

The output, will give you the clue whether the “State” of the Exchange databases are “Consistent” or not (“Inconsistent”).

 

If all databases are consistent, you need to run the following command:

 

                ISINTEG - PATCH

 

NOTE: ISINTEG.EXE needs the System Attendant, Message Transfer Agent and Directory to be started. You can do that by using the Control Panel/Services applet.

 

After that this tool has completed successfully, start up the rest of the services.

4.3.2      Making the databases consistent: caution

 

Assuming that each database is “Inconsistent”. This means that the administrator will have to do some scanning and run some basic integrity checks.

 

The precaution in this case is that you have made a file copy of  the following folders:

 

                \EXCHSRVR\MDBDATA

                \EXCHSRVR\DSADATA

 

4.3.2.1  The scanning itself

 

Note: all the Exchange Services should have been stopped.

 

Exchange 4.0 and 5.0
------------

EDBUTIL.EXE.EXE /d /r /ispriv.
EDBUTIL.EXE.EXE /d /r /ispub.

EDBUTIL.EXE.EXE /d /r /ds.
 
Exchange 5.5
------------
ESEUTIL.EXE /p /ispriv.
ESEUTIL.EXE /p /ispub.

ESEUTIL.EXE /p /ds.
 
NOTE: where x: is the drive containing the required free disk space.

 

After you have run the repair option of the EDBUTIL.EXE or ESEUTIL.EXE tool for each database, you should start up the System Attendant, Message Transfer Agent and Directory Store. It should start now.

Sometimes it happens after starting up the Information Store, your users report that some mail cannot be opened and seems to be corrupted. In this scenario, some additional scanning needs to be done by the administrator.

 

The following command should be executed from the \EXCHSRVR\BIN folder. Note that the System Attendant, Message Transfer Agent and the Directory Store need to be started.

 

Exchange 4.0 and 5.0
------------

ISINTEG –fix –pri.
ISINTEG –fix –pub.
ISINTEG –patch.

 

Exchange 5.5
------------
ISINTEG –fix –pri –test alltests.
ISINTEG –fix -pub -test alltests.

ISINTEG –patch.