Implementation:Ollama Ollama DownloadBlob

Knowledge Sources	Ollama
Domains	Networking, Storage
Last Updated	2026-02-14 00:00 GMT

Overview

Concrete tool for downloading and uploading model blobs with parallel chunked transfer provided by the server package.

Description

downloadBlob handles downloading a single blob by digest. It checks the local cache first, then downloads using HTTP with range request support. Returns a boolean indicating cache hit.

uploadBlob handles uploading a blob to the registry, attempting cross-repository mount first for deduplication, then falling back to chunked upload.

PullModel orchestrates the complete pull flow using downloadBlob for each layer.

Usage

Called internally by PullModel and PushModel for individual blob transfers.

Code Reference

Source Location

Repository: ollama
File: server/download.go (downloadBlob), server/upload.go (uploadBlob)
Lines: download.go:L468-509 (downloadBlob), upload.go:L369-405 (uploadBlob)

Signature

func downloadBlob(ctx context.Context, opts downloadOpts) (cacheHit bool, _ error)

func uploadBlob(ctx context.Context, n model.Name, layer manifest.Layer, opts *registryOptions, fn func(api.ProgressResponse)) error

Import

import "github.com/ollama/ollama/server"

I/O Contract

Inputs (downloadBlob)

Name	Type	Required	Description
ctx	context.Context	Yes	Cancellation context
opts.digest	string	Yes	SHA-256 blob digest to download
opts.n	model.Name	Yes	Model name (for registry URL construction)
opts.regOpts	*registryOptions	Yes	Registry authentication options
opts.fn	func(api.ProgressResponse)	Yes	Progress callback

Outputs (downloadBlob)

Name	Type	Description
cacheHit	bool	True if blob was already cached locally
error	error	Non-nil if download fails
Side effect	Blob file	Downloaded to ~/.ollama/models/blobs/sha256-<hash>

Usage Examples

Pull a Model (uses downloadBlob internally)

# Downloads each blob layer
ollama pull llama3:latest

# Push a model (uses uploadBlob internally)
ollama push my-namespace/my-model:latest

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