# SplitFile.exe create -Input large.vmdk -ChunkSize 500MB -Manifest manifest.json # Use Start-Job / Start-ThreadJob to upload parts in parallel # After upload complete: SplitFile.exe join -Manifest manifest.json -Output large.vmdk
Using cloud provider multipart APIs (conceptual)
- Use SplitFile to produce chunks and manifest.
- Initiate a multipart upload session with the provider.
- Upload each chunk as an individual part; record ETags/part IDs.
- Complete the multipart upload by sending the list of part IDs in order.
- Verify final checksum.
Tips & tricks
- Choose chunk naming that sorts lexicographically (zero-padded numbers) to avoid ordering issues.
- Keep manifest and per-chunk hashes in the same location as chunks or alongside uploads to enable independent verification.
- Compress or deduplicate before chunking if the data is compressible; otherwise compression can waste CPU for incompressible data (like encrypted archives).
- If privacy is a concern, encrypt chunks individually (per-chunk encryption supports end-to-end security and parallel uploading).
- When using parallel uploads, throttle concurrency to avoid hitting API rate limits.
- For huge datasets, consider a two-layer approach: group related files into archives, split those archives, and upload—this reduces per-file metadata overhead.
- Use checksums both per chunk and for the final assembled file; a single final checksum confirms end-to-end integrity.
- Automate clean-up of temporary chunk files after successful verification and reassembly.
Common pitfalls and how to avoid them
- Out-of-order assembly: solve with lexicographic filenames or manifest-enforced ordering.
- Partial uploads left behind: track uploaded parts with a state file and periodically reconcile with the destination.
- API rate limits and throttling: implement rate limiting and exponential backoff.
- Insufficient disk space for intermediate chunks: stream-splitting (creating chunks on the fly and uploading immediately) avoids storing all chunks locally.
- Corrupted chunks: use per-chunk hashing and early verification to detect and redownload only corrupted pieces.
Use cases
- Video production: large raw footage and project files can be split and uploaded concurrently to cloud render farms or collaborators.
- Backups and disk images: break large backups into archive-friendly pieces for cloud storage or cold storage devices.
- Data science & ML datasets: upload massive datasets in parts to training clusters or cloud buckets without hitting single-file limits.
- Software distribution: distribute large installers or game assets via CDN-friendly chunked packages.
- Remote migrations: when transferring VMs or disks between data centers, chunking reduces the cost of retries and can be integrated with multipart APIs for efficient transfer.
Security and compliance considerations
- Encryption: if data is sensitive, encrypt before or during chunking. Use authenticated encryption (e.g., AES-GCM).
- Access control: ensure bucket/object ACLs and temporary upload credentials are least-privilege.
- Audit logs: keep a record of upload operations (who/when) if compliance requires it.
- Retention: plan lifecycle policies for temporary chunks to prevent leaking or unnecessary storage costs.
Final checklist before automating
- [ ] Choose chunk size appropriate for network and destination limits.
- [ ] Create manifest and include per-chunk hashes.
- [ ] Build retry/resume logic with exponential backoff.
- [ ] Test with smaller files first and verify end-to-end checksums.
- [ ] Implement concurrency limits and monitor for rate-limiting.
- [ ] Secure chunks via encryption and restricted credentials if needed.
- [ ] Clean up temporary chunks after successful verification.
Automating large uploads with SplitFile turns a fragile, manual process into a reliable pipeline: chunking reduces risk, enables parallelism and resumability, and gives you fine-grained integrity checks. With careful chunk-size selection, a manifest-driven workflow, and sensible retry/concurrency controls, you can move multi-gigabyte files across unreliable networks with confidence.
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