Applies to: Exchange Server 2010 SP3, Exchange Server 2010 SP2
Topic Last Modified: 2011-03-19
A lagged mailbox database copy is a mailbox database copy configured with a replay lag time value greater than 0. Activating and recovering a lagged mailbox database copy is a simple process if you want the database to replay all log files and make the database copy current. If you want to replay log files up to a specific point in time, it's a more difficult operation because you have to manually manipulate log files and run Eseutil.
Looking for other management tasks related to mailbox database copies? Check out Managing Mailbox Database Copies.
Note: |
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The amount of time it takes to activate a lagged mailbox database copy directly depends on how many log files need to be replayed and how fast the hardware can replay them. At a minimum, you should see a log replay rate of two logs per second per database. |
Prerequisites
- The mailbox database copy being activated must be configured
with a replay lag time greater than 0.
- The mailbox database copy being activated must have all log
files to the point in time to which you want to recover it. Keep in
mind that database transactions can span multiple log files when
determining the point in time to which you want to recover.
Use the Shell to activate a lagged mailbox database copy to a specific point in time
You need to be assigned permissions before you can perform this procedure. To see what permissions you need, see the "Mailbox database copies" entry in the High Availability Permissions topic.
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You can't use the Exchange Management Console (EMC) to activate a lagged mailbox database copy to a specific point in time. |
- Suspend replication for the lagged copy being activated by
using the Suspend-MailboxDatabaseCopy
cmdlet, as shown in this example.
Copy Code Suspend-MailboxDatabaseCopy DB1\EX3 -SuspendComment "Activate lagged copy of DB1 on Server EX3" -Confirm:$false
- Optionally (to preserve a lagged copy), take a file
system-based (non-Exchange aware) Volume Shadow Copy Service (VSS)
snapshot of the volumes containing the database copy and its log
files. You can use the vssadmin.exe tool that's included in Windows
to take a VSS snapshot, as shown in this example.
Copy Code vssadmin create shadow /For=C:\mountpoints\db01 vssadmin create shadow /For=C:\mountpoints\db01_logs
Note: At this point, you have shadow copies outstanding for the database and log volumes. Continuing to perform this procedure on the existing volume would incur a copy on write performance penalty. If this isn't desirable, you can copy the database and log files to another volume to perform the recovery. - Determine which log files are required to replay into the
database to meet your point-in-time requirement for this recovery
(based on log file date and time, as shown in Windows Explorer).
All logs created after this point should be moved to a different
directory, until the recovery process is completed, and the logs
are no longer needed.
- Delete the checkpoint (.chk) file for the database.
- Use Eseutil to perform the recovery operation, as shown in this
example.
Copy Code Eseutil.exe /r eXX /a
Note: In the preceding example, eXX is the log generation prefix for the database (for example, E00, E01, E02, and so on). Important: This step may take a considerable amount of time, depending on several factors, such as the length of the replay lag time, the number of log files generated during that period, and the speed at which your hardware can replay those logs into the database being recovered. - After log replay is finished, the database is in a clean
shutdown state and can be copied and used for recovery
purposes.
- After the recovery process is complete, resume replication for
the database that was used as part of the recovery process, as
shown in this example.
Copy Code Resume-MailboxDatabaseCopy DB1\EX3
For detailed syntax and parameter information, see Suspend-MailboxDatabaseCopy or Resume-MailboxDatabaseCopy.
Use the Shell to activate a lagged mailbox database copy by replaying all uncommitted log files
You need to be assigned permissions before you can perform this procedure. To see what permissions you need, see the "Mailbox database copies" entry in the High Availability Permissions topic.
- Optionally (to preserve a lagged copy), take a file
system-based (non-Exchange aware) Volume Shadow Copy Service (VSS)
snapshot of the volumes containing the database copy and its log
files.
- Suspend replication for the lagged copy being activated by
using the Suspend-MailboxDatabaseCopy
cmdlet, as shown in this example.
Copy Code Suspend-MailboxDatabaseCopy DB1\EX3 -SuspendComment "Activate lagged copy of DB1 on Server EX3" -Confirm:$false
- You can use the vssadmin.exe tool that's included in Windows to
take a VSS snapshot, as shown in this example.
Copy Code vssadmin create shadow /For=C:\mountpoints\db01 vssadmin create shadow /For=C:\mountpoints\db01_logs
Note: At this point, you have shadow copies outstanding for the database and log volumes. Continuing to perform this procedure on the existing volume would incur a copy on write performance penalty. If this isn't desirable, you can copy the database and log files to another volume to perform the recovery.
- Suspend replication for the lagged copy being activated by
using the Suspend-MailboxDatabaseCopy
cmdlet, as shown in this example.
- Activate the lagged mailbox database copy using the Move-ActiveMailboxDatabase
cmdlet with the SkipLagChecks parameter, as shown in this
example:
Copy Code Move-ActiveMailboxDatabase DB1 -ActivateOnServer EX3 -SkipLagChecks