Dell PowerVault DP600 - Manual (Page 96)

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See Also
How DPM Operations Affect Performance
Managing Performance
Synchronization
Synchronization is the process by which DPM transfers data changes from the protected
computer to the DPM server and then applies the changes to the replica of the protected data.
For a file volume or share, the protection agent on the protected computer tracks changes to
blocks, using the volume filter and the change journal that is part of the operating system to
determine whether any protected files were modified. DPM also uses the volume filter and
change journal to track the creation of new files and the deletion or renaming of protected files.
For application data, after the replica is created, changes to volume blocks belonging to
application files are tracked by the volume filter.
How changes are transferred to the DPM server depends on the application and the type of
synchronization. For protected Microsoft Exchange data, synchronization transfers an
incremental Volume Shadow Copy Service (VSS) snapshot. For protected Microsoft SQL Server
data, synchronization transfers a transaction log backup.
DPM relies on synchronization to update replicas with the protected data. Each synchronization
job consumes network resources and can therefore affect network performance.
The impact of synchronization on network performance can be reduced by using network
bandwidth usage throttling and compression. For more information, see Using Network
Bandwidth Usage Throttling and Using On-the-Wire Compression .
See Also
How DPM Operations Affect Performance
Managing Performance
Consistency Check
A consistency check is the process by which DPM checks for and corrects inconsistencies
between a protected data source and its replica.
The performance of the protected computer, DPM server, and network will be affected while a
consistency check is running, but it is expected to be optimized because only the changes and
checksums are transferred.
The network impact from a consistency check is significantly lower than initial replica creation
after a successful replica creation. If the initial replica creation is interrupted or unsuccessful, the
first consistency check can have an impact similar to replica creation.
We recommend that consistency checks be performed during off-peak hours.
DPM automatically performs a consistency check in the following instances:
• When you modify a protection group by changing the exclusion list.