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Multikey is the modern way to run validators on MultiversX. One host runs four observer-style nodes (one per shard) that jointly sign for every key in a shared allValidatorsKeys.pem bundle. mxnode automates the file distribution and per-node config edits.

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Primary install

The keys file is auto-detected at ~/VALIDATOR_KEYS/allValidatorsKeys.pem. Drop it there before installing. What mxnode does:
  1. Builds the node binary once.
  2. For each of the four nodes (shards 0/1/2/metachain):
    • Copies allValidatorsKeys.pem to ~/elrond-nodes/node-{i}/config/ with mode 0600.
    • Stamps Preferences.RedundancyLevel = 0.
    • Stamps Preferences.DestinationShardAsObserver = "<shard>".
    • Enables [DbLookupExtensions] Enabled = true.
  3. Writes 4 systemd units and records everything in state.toml.

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Backup install

Same command, one extra flag:
That stamps RedundancyLevel = 1 on every node. The backup observes the network alongside the primary and only signs when mx-chain-go’s redundancy logic detects the primary has gone silent. For a backup-of-backup chain, increase the level:
--backup with no value defaults to 1 — the common case.
Every redundancy machine must hold the byte-identical allValidatorsKeys.pem. If the bundles diverge, the backup signs for a different key set and the network sees a fork. Verify with sha256sum before installing the backup.

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Concepts

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Explicit keys file path

If your bundle isn’t at the default location (e.g. mounted from a vault):
The file must exist at install time. mxnode does not read it after install — the per-node copies are the source of truth at runtime.

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File permissions

Per-node copies are written with mode 0600 (owner read/write only). The owner is the custom_user from config.toml (auto-detected to your login user during init). No other user on the box can read the keys.

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Verifying

After install, sanity-check each node:
Expected output per node (primary):
For a --backup install, RedundancyLevel reads 1 (or your chosen N) instead.

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Adding nodes later

mxnode add-nodes reuses the existing allValidatorsKeys.pem from node-0 automatically — no --keys-file needed:
The new nodes inherit the bundle and the install’s existing redundancy level. Rotating the bundle across an entire host isn’t a built-in command yet — for now, run mxnode cleanup --yes --execute and reinstall.

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Observer keys

Plain observer installs ship no validatorKey.pem. The mx-chain-go binary generates one on first start when config/ has none, so the observer comes up with a throwaway key without any operator action. For a stable observer identity (e.g. to populate Preferences.Identity), generate a key pair manually with mxnode keygen and drop the resulting validatorKey.pem into the workdir’s config/ before starting the node. See operations.

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Configuration knobs

The relevant per-node fields, all stamped into prefs.toml automatically: Operators who need other prefs can layer overrides via [overrides.prefs] in config.toml — see configuration.