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Recover state from a finalized block

In the highly unlikely event that Linea's sequencer fails, it must be possible to reconstruct Linea's state as it was at the last point in time data was finalized, using L1 data. Conceivably, any entity could then resume transaction sequencing, confident that state was resuming from the correct point.

State recovery insures against the risks of a single point of failure that could cripple the network. Since this system can be used by any independent actor to validate state roots against L1-published data, it also reduces the need for trust in the Linea sequencer and coordinator.

To this end, the Linea Besu execution client has a state recovery plugin that:

  1. Retrieves finalized blobs from L1;
  2. Decompresses the blob data;
  3. Replays the transactions in the execution client, and, finally,
  4. Checks that the resulting stateRootHash matches the one finalized on L1.

Linea Besu executes the fetched transactions in the blob, while the state management plugin, Shomei, rebuilds state.

Prerequisites​

Availability

The state recovery plugin only works from the following block numbers onwards:

  • Linea Mainnet: TBC (once Beta v2 is live)
  • Linea Sepolia: 9572301 (the block where the 2B gas limit was implemented)

State recovery requires that you run:

Linea Besu node​

The Linea Besu node being used must have been running with the following configuration in the .toml file since genesis (i.e. from when it started to sync):

  • FULL sync mode: 
    sync-mode="FULL"
  • BONSAI data storage: 
    data-storage-format="BONSAI"

To learn how to run a Linea Besu node, see our guide.

Shomei​

Shomei is a state manager that communicates with Linea Besu (via the corresponding plugin) to maintain and update state.

See the Shomei repository for information on how to run it; you can access a binary distribution or pull the latest build from Docker Hub.

Configuration​

Update your Linea Besu node and your Shomei configuration using the below instructions.

Linea Besu node​

info

Only enable state recovery if you intend the node to be used specifically for state recovery. Even if you do not specify a block from which state recovery should start, default behavior will ensure that state recovery will replace standard P2P syncing. It's therefore not possible to add the state recovery plugin and configuration without it affecting your node's behavior.

To proceed with state recovery, your node must have been running normally, in line with the above conditions (i.e. FULL sync mode and BONSAI data storage enabled).

Only then can you proceed by adding the following configuration parameters.

Insert them into the .toml configuration file alongside any existing plugin configurations, or via the command line by adding -- before each parameter:

### Plugin Configuration ###
Xplugins-external-enabled=true
Xbonsai-limit-trie-logs-enabled=false
plugins=["BesuShomeiRpcPlugin","ZkTrieLogPlugin","LineaStateRecoveryPlugin"]
plugin-shomei-http-host="..." // Replace with your Shomei host IP address
plugin-shomei-http-port= ... // Replace with your Shomei port
plugin-staterecovery-linea-sequencer-beneficiary-address="0xa27342f1b74c0cfb2cda74bac1628d0c1a9752f2"
plugin-staterecovery-l1-smart-contract-address="0xb218f8a4bc926cf1ca7b3423c154a0d627bdb7e5"
plugin-staterecovery-l1-endpoint="https://sepolia.infura.io/v3/INFURA_APP_KEY"
plugin-staterecovery-l1-polling-interval="PT12S"
plugin-staterecovery-l1-success-backoff-delay="PT2S"
plugin-staterecovery-l1-retry-backoff-delay="PT4S"
plugin-staterecovery-l1-earliest-search-block="7316705"
plugin-staterecovery-l1-highest-search-block="FINALIZED"
plugin-staterecovery-shomei-endpoint="http://shomei-sr-sepolia:8888"
plugin-staterecovery-blobscan-endpoint="https://api.sepolia.blobscan.com"
plugin-staterecovery-overriding-recovery-start-block-number=9572301
note

The plugin-staterecovery-l1-endpoint parameter assumes that you have the variable INFURA_APP_KEY stored in your environment. If not, or if you want to use a different RPC endpoint, ensure you update this.

plugin-staterecovery-overriding-recovery-start-block-number=9572301 will instruct the client to sync as normal, via P2P, until block 9572300, the block before the one specified. After this, it will begin using the state recovery plugin and sync based on data recovered from L1 blobs.

If your node has already synced to a block number greater than the one you specify in this parameter, the state recovery plugin will start on the next block (head block + 1).

Shomei​

Run Shomei in mode 1, which involves enabling these flags, either via the command line or in the configuration file:

--enable-trace-generation=true
--trace-start-block-number=BLOCK_NUMBER // Choose a more recent block for faster syncing

And then ensure that you configure Shomei to be aware of where the Linea Besu node is running:

--besu-rpc-http-host=... // Replace with your Linea Besu node's host
--besu-rpc-http-port=... // Replace with your Linea Besu node's port