Multipart Write


Enable this feature only with Swarm 15 and later versions; do not enable this feature with Swarm 14 and earlier versions.


Multipart Write was previously referred to as Parallel Write; the functionality is the same.

Parts of a large object from multiple clients at the same time can be uploaded with Multipart Write. Multipart Write allows client applications to split a large file into multiple pieces, transfer the pieces concurrently to Swarm, and then request that Swarm combine the separately uploaded parts as a single object, thereby minimizing the upload time.

Multipart write requires The health processor (HP) can consolidate segments of erasure-coded objects with sub-optimal segment usage, as can happen when performing SCSP or S3 multipart writes of objects using small parts. DataCore recommends configuring clients to use 50MB–100MB parts. Set the configuration setting, ec.segmentConsolidationFrequency, to 10 (recommended), which performs all consolidations over 20 HP cycles if consolidation is needed.


Every multipart write must be erasure-coded for upload; the HP converts it to a replicated object if the uploaded object does not meet the current policy for EC encoding. Add a lifepoint to that effect to maintain erasure coding for the lifetime of the object.

Three distinct actions must be performed in this order to upload a large object in parts using multipart write:

  1. Initiate a multipart write.

  2. Upload or copy the parts.

  3. Complete or cancel the procedure.

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