Modes of rolling data conversion
MSDP uses the rolling data conversion mechanism to convert Blowfish encrypted data to AES-256 encrypted data, and MD5-like fingerprints to SHA-512/256 fingerprints, in parallel. There are two modes of data conversion: normal mode and fast mode.
Normal mode: By default, the data conversion process starts in a normal mode for an upgraded system. Similar to compaction, the data conversion runs only when no backup, restore, or Content Router Queue Processing (CRQP) jobs are active.
In the normal mode, the time for data conversion depends on the following factors:
Total size of the storage
Power of the CPU
Workload on the system
Data conversion in the normal mode may take a longer time.
Veritas tests in a controlled environment showed that for a single 1-TB mount point, the conversion speed is about 50MB/s in normal mode.
Fast mode: In the fast mode, the data conversion disables cyclic redundancy checks and compaction. The rolling data conversion runs while backup, restore, duplication, or CRQP jobs are active.
Veritas tests in a controlled environment showed that for a single 1-TB mount point, the conversion speed is about 105MB/s in fast mode.
Note:
The performance numbers shown were observed in the Veritas test environment and are not a guarantee of performance in your environment.
In a new installation of NetBackup 8.1, the rolling data conversion is marked as Finished and does not start in the future. For an upgrade to NetBackup 8.1, the rolling data conversion is enabled by default and works in the background after the MSDP conversion completes. Only the data that existed before upgrade is converted. All new data uses the new SHA-512/256 fingerprint and does not need conversion.
While in Fast mode, the rolling data conversion affects the performance of backup, restore, duplication, and replication jobs. To minimize this effect, use the Normal mode, which pauses the conversion when the system is busy, but slows down the conversion process. The Fast mode keeps the conversion active regardless of system state.
You can manage and monitor the rolling data conversion using the following crcontrol command options.
Table: MSDP crcontrol command options for rolling data conversion
Option | Description |
|---|---|
--dataconverton | To start the data conversion process, use the --dataconverton option: Windows: UNIX: /usr/openv/pdde/pdcr/bin/crcontrol --dataconverton |
--dataconvertoff | To stop the data conversion process, use the --dataconverton option: Windows: UNIX: /usr/openv/pdde/pdcr/bin/crcontrol --dataconvertoff |
--dataconvertstate | To determine the mode of data conversion and the conversion progress, use the --dataconvertstate option: Windows: UNIX: /usr/openv/pdde/pdcr/bin/crcontrol --dataconvertstate |
--dataconvertmode | To switch between the normal mode and fast mode of data conversion, use the --dataconvertmode option: Windows: UNIX: /usr/openv/pdde/pdcr/bin/crcontrol --dataconvertmode <mode> The default value for the <mode> variable is 0, which stands for the normal mode. To switch data conversion from normal mode to fast mode, enter 1 for the value of the <mode>variable. |