IBM TS7650G PROTECTIER DEDUPLICATION GATEWAY, User Manual, Page: 163 / 248

Chapter 15. Optimization
The topics in this section describe how to optimize the performance of the
ProtecTIER system using ProtecTIER Manager.
Changing the CRC setting
This topic explains how to change the CRC calculation algorithm for optimized
backup and replication activities on a DD4 server, or higher.
The Change CRC calculation window allows you to change the CRC calculation
algorithm to a different algorithm that consumes less CPU resources and can help
improve the performance of backup, restore, and replication activities.
CRC is also used in replication communication, regardless of the kind of CRC used
for backups, or replication.
Note: It is recommended that all repositories within a replication group have
ProtecTIER version 3.1.8, or higher. If the version level of a member in the
replication group does not support the fast 32-bit CRC calculation, replication will
fail.
Typically, changing the CRC calculation is a onetime event. Once the calculation is
changed from the default value, you are not expected to change the calculation
back to the default setting. When new data is written to the repository, the latest
CRC algorithm selected is used.
"Old" data remains with the CRC calculation that was selected at the time of
backup. Even if the "old" data is replicated, the CRC calculation that was selected
at the time of backup remains the same and is transferred togetherwith the
replicated data.
Note: Changing the CRC calculation does not affect deduplication in any way.
You can change the CRC calculation algorithm from the Systems Management
view in ProtecTIER Manager. To access the CRC calculation window, select
System
> Optimization > CRC calculation.
Select a CRC calculation option from the dropdown list:
v Software 64-bit CRC
v Hardware/Software fast 32-bit CRC
Click Ok to save and exit the window.
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