Starting with version 1.0.70 the DiRT backup application offers the option to include subscriber messages as part of the backup if you’re back end is Exchange.  Before selecting this option on your system it’s important to understand what this does and what impact it can have on your backup.  The DiRT mailstore backup option is supported for backing up your Exchange message store only in the following situations:

1. A one-time migration (any number of users/mailboxes)

2. Regular or periodic mailstore backup of smaller systems (200 users or less).

Except as noted with one-time migrations Cisco does not support the use of DiRT as a replacement for regular/periodic mailstore backups of your Exchange system.  Mor migration purposes it will work on any configuration but the space needed for message backup can be very large (i.e. much larger than the size of the Exchange PRIV.EDB file) so proceed with caution.

Microsoft’s ExMerge

The DiRT utilities leverage the ExMerge utility that ships with Exchange 2000 CD.  This version has several new features and many bug fixes in it that are required for DiRT to be able to automatically spawn it on the fly.  Note that even though this version comes with the Exchange 2000 CD it does work with Exchange 5.5 SP2 or later as well.

ExMerge is designed to extract some or all of selected users’ mailbox into a standard PST file on the hard drive.  You can pass it a file containing a list of all the mailboxes you want to backup and which parts of the mailbox you want to get (i.e. just the inbox, or include the sent items folder, deleted items folder etc…).  

Space Needed For Messages

Using ExMerge has some advantages and disadvantages.  One advantage, for instance,  is you can easily restore a single user’s mailbox by simply going to the backup target directory and importing the PST file for that user with Outlook.  One big disadvantage is you lose single instance messaging.  When you send a message to a group of people, Exchange makes sure that only one copy of that messages goes to each Exchange server that has at least one recipient on the TO list.  So if 100 users homed on a specific Exchange server get the message, only one copy of it is stored in the PRIV.EDB database.  However, when you backup those 100 people’s mailboxes to individual PST files, each one gets a copy of that message.  As such it’s impossible to estimate the amount of hard drive space you may need before actually backing them up.  This applies to restoring them as well.  If you restore those user’s mailboxes the PRIV.EDB will grow in this case since ExMerge cannot tell that a message in each PST file are identical so each mailbox gets it’s own copy.

Sites using UM will be much more likely to have large numbers of group messages and will definitely get bit by this harder than the typical VM only site, but that’s not a hard and fast rule.  Make sure you understand this scenario before deciding to use DiRT to do regular backups of your subscriber messages.

Short story, make sure you have plenty of space for backups.  DiRT is designed such that essential Unity data is backed up first and then messages.  If HD space runs out the message backup will simply stop.  All user that had their messages backed up until that point are fine, however.

Restoring Messages For Single Subscribers

As mentioned above each mailbox is backed up to it’s own PST file where the name of the file is the Alias (Mail nickname) of the subscriber.  You can find the PST files in the target backup directory under the “Messages” folder.  To restore an individual subscriber’s messages from the last backup you can use Outlook to import the PST file into their mailbox.   If Outlook is not available, you can use ExMerge directly to do this for one or several subscribers.  You’ll find the ExMerge executable under \Program Files\Exchsrvr\Bin.  When run directly it has a GUI interface you can walk through to import messages for specific users.  Just select the users form the directory you want to restore messages for and then browse to the target backup directory’s “Messages” folder and it should do the rest.  You need to do this logged in as an account that has Exchange Service account rights.  See the “Configuring Permissions For DiRT” for more on that.

NOTE: You can also restore individual greetings and voice names for subscriber or call handlers.  These are stored as WAV files in the “StreamFiles” directory in the target backup directory and can simply be copied back into the \Commserver\StreamFiles directory. Each WAV file is named with the alias of the object its associated with (subscriber or call handler) and which file it is (day greeting, alternate greeting, voice name etc…).  Finding the file you’re looking for is generally pretty easy.

Issues with Hidden Mailboxes

ExMerge does not properly handle hidden mailboxes in Exchange 2000.  If you are backing up or restoring messages on an Exchange 2000 system that has hidden mailboxes you’ll need to “unhide” them long enough to finish the operation and then hide them again. You can use the Message Store Manager (available on www.CiscoUnityTools.com) to help do this in bulk.

ExMerge does handle hidden mailboxes in Exchange 5.5 correctly.  

To be clear, this is an issue with ExMerge and there’s nothing we can do from DiRT’s side of the fence to get around this.

Issues With Commas In Organization Names

If you are backing up or restoring messages to a system that has a comma in the organization name (i.e. “Cisco Systems, Inc.”), the process will most likely fail for you.  Microsoft’s ExMerge does not deal with commas in the organization name properly and since DiRT uses ExMerge for the messaging portion of the backup and restore you will have problems here.  Commas in organization names were allowed in Ex55, although they can cause numerous problems, but are no longer allowed in Exchange 2000/AD.  

Issues With Mailbox Creation Delays

If you’re DiRT restore is creating a number of new mailboxes as part of the restore (i.e. as opposed to linking up with mailboxes already there) you can experience a period of time when the accounts are in Active Directory but do not actually have a mailbox resource available yet.  The Recipient Update Service (RUS) takes care of this in the background and in most cases will be pretty quick about this.  However in scenarios where there are child domains or simply large numbers of new accounts being added this can lag.  If ExMerge is run to restore messages against accounts that don’t have mailbox resources assigned yet, those mailboxes will fail to get their messages back.  You’ll see an error in the ExMerge output log files that looks similar to this:

Error extracting information from server DN ‘’ {CMAPISession::GetInformationFromProfile

You can run ExMerge manually yourself again after the DiRT restore completes if you see this problem.