Problem : If your server goes down and you need to restore email functionality
without the concern of previous mailbox data, is there some way to
restore email to your users without worrying about the mailbox data
until a later time? How would that be performed?
Solution : Because the mailbox itself is part of Active Directory and the actual
mailbox data is within the Exchange databases, it is possible to restore
an Exchange server quickly to the point of users having the capability
to send and receive email again. This provides time for the actual
database restoration to occur. This is called a dial-tone restore (also
called the recover now, restore later method).
Some of the stress of this method comes from merging
the two sets of data (the old recovered data with the new email sent
back and forth in the dial-tone recovery database).
Keep in mind that there
are several reasons to perform a dial-tone restore. One is that you have
a failed server, and you need to use an alternate server for the
restoration of email services. Another is that you simply have a failed
or corrupt database that is just going to take too long to restore and
your users need email now (so you might use the same server). You have
to make some decisions regarding leaving the data on the recovery server
or moving it back when the crisis is under control.
Perform a Dial-Tone Recovery on the Same Server
To mimic the failed
database, you can dismount the database and locate the database file and
delete it (or move it to another location). In Step 2, you create a new
database, which
does not require mailbox movements because this is the same server and
storage group you are recreating. This gives you the time to recover the
data to the RSG while your users have up-and-running mailboxes.
To achieve dial-tone recovery, perform the following:
1. | If you have any log files from the failed database, you might want to move them to another location. They might be useful.
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2. | Open the EMC.
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3. | Attempt to mount the database and you receive the message shown in Figure 1 regarding the creation of an empty database. Click Yes to continue.
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4. | From the Navigation Tree, expand the Toolbox work center.
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5. | From the options, open the Database Recovery Management tool.
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6. | Create a recovery group for the failed database.
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7. | Restore
the backup you have of the failed database, but do not mount the
database if you have any log files from the failed database. Place those
in the proper location before mounting.
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8. | Mount the database from the task center.
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9. | From the task center, select the Swap Databases for Dial-Tone scenario.
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10. | Make sure the database is correct.
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11. | Select Gather Swap Information.
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12. | Select Perform Swap Action after confirming the information is accurate.
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13. | After the procedure is complete, the configurations for the original and recovery databases are swapped and remounted.
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Swapping databases
provides users the original mailboxes they had, but moves over the
dial-tone database. The two should be merged to ensure no data is lost.
To do this, go back to the
task center and use the Merge or Copy Mailbox Contents settings (just as
you would with a normal recovery group) and merge that content over to
the recovered and swapped database.
When you are done, remove the RSG.
Perform a Dial-Tone Recovery on a Different Server
The
steps for a “new server” dial-tone recovery are almost identical to
that of a “same server” dial-tone recovery. Here are some changes and
additions:
You have to create a new storage group and database with the names of the original on the new server.
You need to use the Move-Mailbox -ConfigurationOnly
command to point the user’s mailboxes to the new database. In doing
this, you are moving the configuration information, but the data will be
restored with the restoration process. The official command is:
Get-Mailbox -Database <Mailbox Server Name\Storage Group
Name\database name> | Move-Mailbox -ConfigurationOnly -TargetDatabase <Mailbox Server
Name\Storage group
Name\Dial Tone database
name>
If
you plan to restore your backup to the new server, the steps are the
same as previously explained. If you plan to restore your backup to the
failed server, you need to use the same EMS command to move the
mailboxes back when you are done.
Note
Users might be
somewhat surprised when they have no email. However, they might be even
more surprised if they have email but no access to all their messages.
You will want to alert them with a message about what is happening. Some
people receive a message that gives them the capability to see their
old data if they have Outlook 2007 in cached mode. However, if they
choose to use old data, they cannot send and receive. They will be
presented with the option to use a temporary mailbox, and this is the
option they need to select to send and receive messages.
