CLUSTER MIGRATION

Start, monitor, and cancel atomic slot migration tasks.

Browse all commands · Upstream source documentation

Reference field	Value
Canonical name	CLUSTER MIGRATION
Catalog group	Cluster commands
Upstream since	8.4.0 — upstream Redis/module version, not an ffkv release
Pinned catalog	Redis 8.10.0

Syntax

CLUSTER MIGRATION <IMPORT start-slot end-slot
  [start-slot end-slot ...] | CANCEL <ID task-id | ALL> |
  STATUS <[ID task-id] | [ALL]>>

ffkv behavior and limits

Requires —cluster-enabled. Hash slots, MOVED/ASK, membership, migration and failover use ffkv’s authenticated peer bus, not the Redis cluster bus. Do not attempt to join a Redis cluster. Tested behavior is not production-HA certification.

Source: README.md:625–642; tests/bdd/features/cluster.feature.

All requests share the 8 MiB framing/1,024-argument ingress limit; normal RESP replies have 64 MiB wire/logical budgets with bounded nesting/value counts. Management and Lua origins impose smaller budgets. These are not a process RSS cap. Catalog inclusion is not exhaustive option or wire-format parity. See limits and compatibility.

Upstream metadata

The following fields come from the pinned Redis metadata, not measured ffkv performance or an assertion that ffkv enforces every upstream flag. Running COMMAND INFO/COMMAND DOCS describe the current engine.

Upstream Redis complexity: O(N) where N is the total number of the slots between the start slot and end slot arguments.

Upstream arity: -4 (includes the command name; a negative number is a minimum).

Command flags: NO_ASYNC_LOADING, ADMIN, STALE.

Argument structure

Argument	Type	Constraints / metadata
subcommand	oneof	Required
↳ import	block	multiple; token: IMPORT
↳ ↳ start-slot	integer	Required
↳ ↳ end-slot	integer	Required
↳ cancel	oneof	token: CANCEL
↳ ↳ task-id	string	token: ID
↳ ↳ all	pure-token	token: ALL
↳ status	oneof	token: STATUS
↳ ↳ task-id	string	optional; token: ID
↳ ↳ all	pure-token	optional; token: ALL

Additional pinned upstream metadata

{
  "group": "cluster",
  "since": "8.4.0"
}

Metadata source · Local snapshot: src/command_metadata.json, key cluster|migration.

BDD coverage and source examples

These are source observations, not a test run performed by this documentation build. A tag identifies scenario intent; an extracted vector identifies a command invocation, which may intentionally produce an error. Scenarios may require setup, multiple connections, persistence, cluster nodes or native-module fixtures.

• Atomic import transfers real typed data and survives destination restart — tests/bdd/features/cluster.feature:498; command tag and invocation observed.
• Concurrent writers follow the actual slot handoff without losing the last acknowledged value — tests/bdd/features/cluster.feature:567; command tag and invocation observed.
• Destination cancellation interrupts a real pending source connection — tests/bdd/features/cluster.feature:585; command tag and invocation observed.
• Snapshot cancellation cleans invisible imported data and resumes source writes — tests/bdd/features/cluster.feature:613; command tag and invocation observed.
• Canceling the live mutation stream retains the source and hides destination data — tests/bdd/features/cluster.feature:974; command tag and invocation observed.
• Function and search metadata accompany migrated keys without replacing unrelated catalogs — tests/bdd/features/cluster.feature:1011; command tag and invocation observed.
• Live resolved mutations replay list changes deletion and absolute expiry exactly once — tests/bdd/features/cluster.feature:1109; command tag and invocation observed.
• Import validation rejects replica destinations multiple sources and overlapping ranges — tests/bdd/features/cluster.feature:1196; command tag and invocation observed.

Extracted command vectors

The following JSON arrays are the test harness’s argument vectors, not shell commands. Numeric arguments are converted by the harness; objects of the form {"base64":"…"} represent decoded binary bytes, not a literal JSON command argument. Preserve scenario setup and connection ordering. See the CLI guide for shell quoting and binary stdin. No reply is invented or inferred.

Destination cancellation interrupts a real pending source connection — tests/bdd/features/cluster.feature:603 (node “node2” executes:)

[
  "CLUSTER",
  "MIGRATION",
  "CANCEL",
  "ALL"
]

Next source assertion: the reply equals:

0

Import validation rejects replica destinations multiple sources and overlapping ranges — tests/bdd/features/cluster.feature:1213 (node “node3” executes:)

[
  "CLUSTER",
  "MIGRATION",
  "STATUS",
  "ALL"
]

Next source assertion: the reply equals:

[]

Atomic import transfers real typed data and survives destination restart — tests/bdd/features/cluster.feature:557 (node “node2” executes:)

[
  "CLUSTER",
  "MIGRATION",
  "STATUS",
  "ID",
  "unknown"
]

Next source assertion: the reply equals:

[]