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January 30, 2026 - CoreWeave AI Object Storage RenameObject API

CoreWeave AI Object Storage now supports atomic object renaming with the RenameObject API

New Storage CoreWeave AI Object Storage now supports the RenameObject API, providing atomic, server-side rename operations for objects within the same bucket. RenameObject updates index entries instead of copying data, so rename operations complete in milliseconds regardless of object size.

Overview​

The RenameObject API provides a simpler and more efficient alternative to copy-and-delete workflows. Key benefits include:

  • Atomic operation: No window where both keys exist simultaneously
  • No data movement: Updates metadata only, avoiding copy latency and temporary storage duplication
  • Metadata preservation: Encryption settings, storage billing tier, checksums, and other attributes are preserved
  • Precondition support: ETag and time-based conditions guard against race conditions and accidental overwrites

Use cases​

Use caseDescription
Checkpoint promotionRename temporary checkpoints to final names after training runs complete
Batch finalizationMove artifacts from staging prefixes to final locations after validation
Log rotationAtomically "lock" time-based prefixes by renaming to finalized paths

Limitations​

  • Same bucket only — cross-bucket rename is not supported
  • Versioning not supported — buckets with versioning enabled or previously enabled cannot use RenameObject
  • Single object per request — prefix-level rename must be implemented as client-side batches

Learn more​

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