Storage topology DDL

Status: Experimental

Storage topology DDL describes how the local engine maps durable roles onto resources. It does not provision disks or create remote replicas.

Resources

CREATE STORAGE RESOURCE nvme0 (
  type = 'local_disk',
  path = '/mnt/nyxdb/nvme0',
  roles = ['data'],
  max_bytes = 2000000000000,
  node_id = 'local'
);

CREATE STORAGE RESOURCE nvme1 (
  type = 'local_disk',
  path = '/mnt/nyxdb/nvme1',
  roles = ['data'],
  max_bytes = 2000000000000,
  node_id = 'local'
);

The path must be mounted and writable by the NYXDB process before the resource is used.

Pools

CREATE STORAGE POOL fast (
  resources = ['nvme0', 'nvme1'],
  placement = 'mirror'
);

Supported placement values are jbod and mirror. The current runtime is single-node; a mirror is local storage placement, not a high-availability replica.

Policies

CREATE STORAGE POLICY trading (
  serve_pool = 'fast',
  durable = {pool: 'fast'},
  delta = {
    flush_rows: 262144,
    flush_bytes: 268435456,
    flush_after_ms: 5000
  },
  compaction = {strategy: 'merge_tree'},
  ttl = 'observed_at < now() - INTERVAL 30 DAY'
);

This example omits wal and uses the engine's synthesized local WAL placement. An explicitly named WAL pool has a narrower contract than a data pool: it must be a non-draining jbod pool with exactly one local-disk member whose path is exactly --data-dir. A mirrored or multi-member WAL pool is rejected, and a second resource at the data-directory root can conflict with the synthesized default resource. Keep the default unless the exact topology has been validated against the target release.

A policy can also declare tiered durable placement where supported by the release. Reference the policy from CREATE TABLE ... SETTINGS storage_policy = 'trading'.

Change and inspect topology

CREATE STORAGE RESOURCE nvme2 (
  type = 'local_disk',
  path = '/mnt/nyxdb/nvme2',
  roles = ['data'],
  max_bytes = 2000000000000,
  node_id = 'local'
);

ALTER STORAGE POOL fast ADD RESOURCE nvme2;
ALTER STORAGE POOL fast DRAIN RESOURCE nvme1;
ALTER STORAGE POOL fast REMOVE RESOURCE nvme1;

SHOW STORAGE RESOURCES;
SHOW STORAGE POOLS;
SHOW STORAGE POLICIES;

Drain a resource and verify evacuation before removal. The engine rejects unsafe or inconsistent transitions.

DROP STORAGE POLICY trading;
DROP STORAGE POOL fast;
DROP STORAGE RESOURCE nvme0;

Dependencies must be removed first.

For production layout, mount and recovery guidance, see Storage operations.