#Volume Fork

Volume Fork creates a new Volume from an existing Volume using JuiceFS Copy-on-Write (COW) clone.

Why Use Fork?#

• Fast Clone: Create a new Volume quickly without copying all data blocks
• Storage Efficient: Source and fork share unchanged data blocks
• Write Isolation: Writes to the fork do not affect the source Volume
• Great for Branching: Create per-task or per-experiment data branches

How Fork Works#

API#

• Endpoint: POST /api/v1/sandboxvolumes/{id}/fork
• Path Parameter: id is the source Volume ID
• Request Body: Optional, used to override inherited configuration from the source Volume
• Success Response: 201 Created, returns the new SandboxVolume including source_volume_id
• Common Errors: 400 (invalid access_mode), 404 (source Volume not found or not visible to your team)

Optional Request Fields#

Fork a Volume#

go
forked, err := client.ForkVolume(ctx, volume.ID, &apispec.ForkVolumeRequest{
  AccessMode: apispec.NewOptVolumeAccessMode(apispec.VolumeAccessModeRWO),
  CacheSize:  apispec.NewOptString("2G"),
  BufferSize: apispec.NewOptString("64M"),
  Prefetch:   apispec.NewOptInt(10),
  Writeback:  apispec.NewOptBool(false),
})
if err != nil {
  panic(err)
}

fmt.Printf("Forked Volume: %s
", forked.ID)
if sourceVolumeID, ok := forked.SourceVolumeID.Get(); ok {
  fmt.Printf("Source Volume: %s
", sourceVolumeID)
} else {
  fmt.Println("Source Volume: <nil>")
}

Verify Isolation#

1. Mount both the source and the forked Volume to a Sandbox at different paths.
2. Modify a file only in the forked Volume.
3. Read the same file from the source Volume and verify it is unchanged.

Next Steps#