Automatic checksum generation and verification of replicated data have been available in Tiger Bridge since version 5.1. This article covers the best practices, troubleshooting techniques, and corner cases when checksum generation is enabled.
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:
- 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.
- 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 before you force replicate an offline file, you must first rehydrate it from the archive to the hot or cool tier/storage class of the target, using either of these commands:
tiercli op move_hot <path to file or folder>
tiercli op move_cool <path to file or folder>
Important: Be aware of the incurred costs on the cloud storage target of re-replicating data and rehydrating data from the archive.
- 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”. - 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 - To verify that a checksum is generated, execute the following:
tiercli op info <path to a file or a whole folder>