Transfer Service

Transfer is an independent service for Load and Export jobs. It persists job state, plans work from mount and Worker information, dispatches tasks to Workers, and receives task reports. It does not host a replica of the full Curvine metadata tree.

Deploy Transfer after the Master and Workers are healthy. It is optional: a cluster that does not enable Transfer continues to use the legacy Master Load and Export path.

Configuration Boundary

The service and the client use different Transfer settings. Do not change the running Master or Worker configuration merely to deploy Transfer.

Component	Required change	Notes
Transfer service	Set transfer.enabled = true, a persistent store_url, and a reachable endpoint.	The service configuration must also contain the existing cluster's Master addresses.
CLI or SDK client	Set transfer.enabled = true and transfer.endpoints.	cv load, cv export, and compatible status/cancel commands then use Transfer automatically.
Master	None. Keep Transfer disabled during staged rollout.	Enabling it makes the Master reject the legacy Load and Export RPCs.
Worker	None.	Workers need a version that supports Transfer tasks. Report endpoints are included in each task.

The client configuration contains no database URL. The store belongs only to the Transfer service.

Choose a State Store

Store	Topology	Use it when
SQLite	One Transfer instance and one persistent local volume.	Evaluation, development, or a single-instance deployment.
MySQL	Two or more Transfer instances sharing one database.	Production high availability and rolling service upgrades.

Never point multiple Transfer instances at independent SQLite files. They would hold different job state and cannot fail over correctly.

Required Configuration

The Transfer server needs a complete cluster configuration, including [client] Master addresses. Add this section only to the Transfer server's configuration file:

[transfer]
enabled = true
store_url = "sqlite:///var/lib/curvine-transfer/transfer.db"
hostname = "transfer-1.example.com"
endpoints = ["transfer-1.example.com:9010"]

For a MySQL-backed service, replace store_url with a shared MySQL URL. Do not put credentials in a client configuration file or a ConfigMap.

Clients need only the routing settings:

[transfer]
enabled = true
endpoints = ["transfer-1.example.com:9010"]

If endpoints is omitted, Curvine derives one endpoint from hostname:rpc_port. Explicit endpoints are recommended for Kubernetes and for any address that differs from the bind address.

Deploy and Verify

• Deploy on bare metal
• Deploy on Kubernetes
• Transfer configuration reference

After deployment, run cv transfer list from a client configured for Transfer. Submit a small mounted UFS file with cv load <path> --watch, then verify that the job reaches Completed and the target can be read with cv fs --cache-only get.

Rollout and Rollback

Enable Transfer in clients gradually. A client with transfer.enabled = false continues to use the legacy Master job API, so deploying the service alone does not change existing workloads. To roll back a client, disable Transfer in that client configuration; do not delete a Transfer store while jobs are active.