Tiger Bridge Checksum Generation: Best Practices and Troubleshooting

Best Practices 

Generating Checksums for Files Replicated with a Previous Version 

If your source contains data replicated with an earlier version of Tiger Bridge, you need to re-replicate it to the target to enable checksum generation for this data too. If you prefer not to modify the data to queue it for re-replication, you can force replicate it using the steps described in Regenerating the Checksum of a File Without Modifying It. 

Using the Checksum Feature on Non-Azure Targets 

For all targets except Azure, checksum verification is not automatic. You are responsible for ensuring that a tool capable of generating checksums is running on the target, and for manually verifying that the checksum generated on the target matches the one generated by Tiger Bridge on the source. 

When configuring checksum generation in Tiger Bridge: 

1. Ensure Matching Algorithms: Configure Tiger Bridge to use the same checksum algorithm as the one used on the target. Using different algorithms will result in mismatched checksums, even if the data is unaltered.
2. Changing the Algorithm: You can change the checksum algorithm in Tiger Bridge at any time. However, already replicated data will retain the checksum value created with the previous algorithm. To apply the new algorithm to this data, you must either: 
   • Modify the file on the source to queue it for re-replication. 
   • Use the command-line interface to force replication. For details, refer to Regenerating the Checksum of a File Without Modifying It. 

If the target does not support checksum generation, you can work around this limitation by retrieving the replicated file from the target to a local storage location (different from your source, to avoid overwriting) and running the same checksum algorithm locally. You can then compare the two checksum values to verify data integrity on the target. 

Troubleshooting Missing Checksum 

Regenerating the Checksum of a File Without Modifying It 

Tiger Bridge generates a checksum before replicating a file. If the checksum of a replicated file is missing, or if you want to use a different algorithm without modifying the file, you can force-replicate it through the command-line interface.

Note that to force replicate a stub file, you must first retrieve it manually from the target (for stub files pointing to the archival tier/storage class of the target, you must first rehydrate them to the hot or cool tier/storage class).  You can do this using the Tiger Bridge shell extension or with the following command-line interface commands: 

• To retrieve a nearline stub from the target:

tiercli op restore <path to a file or a folder>

• To rehydrate an offline stub file from the archive:

tiercli op move_hot <path to file or folder>

tiercli op move_cool <path to file or folder>

1. Run Command Prompt as an administrator. 
   Tip: To run Command Prompt as an administrator, click Start, type cmd, right-click Command Prompt, and select “Run as administrator”. 
2. Execute the following:
   tiercli op replicate -f <path to file or folder on the source > 
   For example, to reset the replicated status of all replicated files in the folder ”Archive” in the root of the drive D added as a source, execute the following: 
   tiercli op replicate -f D:\Archive 
3. To verify that a checksum is generated, execute the following: 
   tiercli op info <path to a file or a whole folder>