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Genesis replay re-executes historical blocks so that additional copies of state are available at any given point in time. Historically, blocks have been stored in a static archive format. This process downloads those blocks and replays them through the EVM to reconstruct full state.

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Prerequisites

  • monad version 0.12.3 or later
  • Credentials and configuration to read from your chosen archive source (AWS, R2, MongoDB, MinIO, etc.). These are the same credentials used by monad-archiver; see Running an Archive Server for details.

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Setup

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1. Prepare the block database directory

Choose a directory to store EVM-format historical blocks. This guide refers to it as block-db.

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2. Initialize triedb

Create an empty triedb: 
monad-mpt \
    --storage /dev/triedb \
    --root-offsets-chunk-count 16 \
    --create-empty

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3. Start the block writer

Run inside tmux or create a systemd service to download blocks continuously: 
monad-block-writer stream \
    --block-data-source <your source string> \
    --dest-path <your block-db path>
The source string follows the same format used by monad-archiver, for example "aws mainnet-deu-009-0" or "mongodb ...". The block writer will:
  1. Download all blocks from the source
  2. Transform them into EVM format
  3. Brotli-compress the data
  4. Write blocks into subdirectories of the form block-db/XM/<block_number>, where X = block_number / 1_000_000 (one million blocks per directory)
Resumption behavior: The writer saves a latest file in the block-db directory. If the process stops, on the next startup it reads latest and compares it against the latest block available from the --block-data-source, then continues from that point.
If you only need a specific range of blocks, run monad-block-writer stream --help for range options.

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4. Configure the replay service

While monad-block-writer is running, add the following systemd override for monad-execution in a separate terminal: 
sudo systemctl edit monad-execution

[Service]
ExecStart=
ExecStart=/usr/local/bin/monad \
    --chain "$CHAIN" \
    --as_eth_blocks \
    --block_db <your block-db path> \
    --nblocks 0 \
    --db /dev/triedb \
    --no-compaction \
    --trace_calls \
    --block-db-timeout 60

AllowedCPUs=
CPUAffinity=
Restart=
Restart=always
Ensure $CHAIN is defined in your environment. Valid options:
  • ethereum_mainnet
  • monad_devnet
  • monad_testnet
  • monad_mainnet
--block-db-timeout sets the number of seconds the replay service will wait for new blocks to appear in the block database. If the timeout is reached without new blocks, the replay service will crash and be restarted by systemd. If this happens, verify that the block writer from step 3 is still running and writing blocks to disk. Set to 0 to disable retries.

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5. Reload and start

sudo systemctl daemon-reload
sudo systemctl restart monad-execution

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Running RPC on a replay host

If you want to run monad-rpc on this host, you must remove the --ipc-path flag from the monad-rpc systemd configuration.