Batcher configuration

This page lists all configuration options for the op-batcher. The op-batcher posts L2 sequencer data to the L1, to make it available for verifiers. The following options are from the --help in v1.10.0 (opens in a new tab).

Batcher Policy

The batcher policy defines high-level constraints and responsibilities regarding how L2 data is posted to L1. Below are the standard guidelines for configuring the batcher within the OP Stack.

Additional Guidance

• Data Availability Types:

  • Calldata is generally simpler but can be more expensive on mainnet Ethereum, depending on gas prices.
  • Blobs are typically lower cost when your chain has enough transaction volume to fill large chunks of data.
  • The op-batcher can toggle between these approaches by setting the --data-availability-type=<blobs|calldata|auto> flag or with the OP_BATCHER_DATA_AVAILABILITY_TYPE env variable. Setting this flag to auto will allow the batcher to automatically switch between calldata and blobs based on the current L1 gas price.

• Batch Submission Frequency (OP_BATCHER_MAX_CHANNEL_DURATION and related flags):

  • Standard OP Chains frequently target a maximum channel duration between 1–6 hours.
  • Your chain should never exceed your L2's sequencing window (commonly 12 hours).
  • If targeting a longer submission window (e.g., 5 or 6 hours), be aware that the safe head (opens in a new tab) can stall up to that duration.

• Output Frequency:

  • Used to post output roots to L1 for verification.
  • The recommended maximum is 24 hours (43,200 blocks at 2s each), though many chains choose smaller intervals.
  • Will eventually be replaced or significantly changed by the introduction of fault proofs.

Include these high-level "policy" requirements when you set up or modify your op-batcher configuration. See the Batcher Configuration reference, which explains each CLI flag and environment variable in depth.

Recommendations

Set your OP_BATCHER_MAX_CHANNEL_DURATION

To minimize costs, we recommend setting your OP_BATCHER_MAX_CHANNEL_DURATION to target 5 hours, with a value of 1500 L1 blocks. When non-zero, this parameter is the max time (in L1 blocks, which are 12 seconds each) between which batches will be submitted to the L1. If you have this set to 5 for example, then your batcher will send a batch to the L1 every 5*12=60 seconds. When using blobs, because 130kb blobs need to be purchased in full, if your chain doesn't generate at least ~130kb of data in those 60 seconds, then you'll be posting only partially full blobs and wasting storage.

• We do not recommend setting any values higher than targeting 5 hours, as batches have to be submitted within the sequencing window which defaults to 12 hours for OP chains, otherwise your chain may experience a 12 hour long chain reorg. 5 hours is the longest length of time we recommend that still sits snugly within that 12 hour window to avoid affecting stability.
• If your chain fills up full blobs of data before the OP_BATCHER_MAX_CHANNEL_DURATION elapses, a batch will be submitted anyways - (e.g. even if the OP Mainnet batcher sets an OP_BATCHER_MAX_CHANNEL_DURATION of 5 hours, it will still be submitting batches every few minutes)

Configure your batcher to use multiple blobs

The op-batcher has the capabilities to send multiple blobs per single blob transaction. This is accomplished by the use of multi-frame channels, see the specs (opens in a new tab) for more technical details on channels and frames.

A minimal batcher configuration (with env vars) to enable 6-blob batcher transactions is:

  - OP_BATCHER_BATCH_TYPE=1 # span batches, optional
  - OP_BATCHER_DATA_AVAILABILITY_TYPE=blobs
  - OP_BATCHER_TARGET_NUM_FRAMES=6 # 6 blobs per tx
  - OP_BATCHER_TXMGR_MIN_BASEFEE=2.0 # 2 gwei, might need to tweak, depending on gas market
  - OP_BATCHER_TXMGR_MIN_TIP_CAP=2.0 # 2 gwei, might need to tweak, depending on gas market
  - OP_BATCHER_RESUBMISSION_TIMEOUT=240s # wait 4 min before bumping fees

This enables blob transactions and sets the target number of frames to 6, which translates to 6 blobs per transaction. The minimum tip cap and base fee are also lifted to 2 gwei because it is uncertain how easy it will be to get 6-blob transactions included and slightly higher priority fees should help. The resubmission timeout is increased to a few minutes to give more time for inclusion before bumping the fees because current transaction pool implementations require a doubling of fees for blob transaction replacements.

Multi-blob transactions are particularly useful for medium to high-throughput chains, where enough transaction volume exists to fill up 6 blobs in a reasonable amount of time. You can use this calculator (opens in a new tab) for your chain to determine what number of blobs are right for you, and what gas scalar configuration to use. Please also refer to guide on Using Blobs for chain operators.

Set your --batch-type=1 to use span batches

Span batches reduce the overhead of OP Stack chains, introduced in the Delta network upgrade. This is beneficial for sparse and low-throughput OP Stack chains.

The overhead is reduced by representing a span of consecutive L2 blocks in a more efficient manner, while preserving the same consistency checks as regular batch data.

Batcher Sequencer Throttling

This feature is a batcher-driven sequencer-throttling control loop. This is to avoid sudden spikes in L1 DA-usage consuming too much available gas and causing a backlog in batcher transactions. The batcher can throttle the sequencer's data throughput instantly when it sees too much batcher data built up.

There are two throttling knobs:

1. Transaction L1 data throttling, which skips individual transactions whose estimated compressed L1 DA usage goes over a certain threshold, and
2. block L1 data throttling, which caps a block's estimated total L1 DA usage and leads to not including transactions during block building that would move the block's L1 DA usage past a certain threshold.

Feature requirements

• This new feature is enabled by default and requires running op-geth version v1.101411.1 or later. It can be disabled by setting --throttle-interval to 0. The sequencer's op-geth node has to be updated first, before updating the batcher, so that the new required RPC is available at the time of the batcher restart.
• It is required to upgrade to op-conductor/v0.2.0 if you are using conductor's leader-aware rpc proxy feature. This conductor release includes support for the miner_setMaxDASize op-geth rpc proxy.

Configuration

The batcher can be configures with the following new flags and default parameters:

• Interval at which throttling operations happen (besides when loading an L2 block in the batcher) via --throttle-interval (env var OP_BATCHER_THROTTLE_INTERVAL): 2s
• This can be set to zero to completely disable this feature. Since it's set to 2s by default, the feature is enabled by default.
• Backlog of pending block bytes beyond which the batcher will enable throttling on the sequencer via --throttle-threshold (env var OP_BATCHER_THROTTLE_THRESHOLD): 1_000_000 (batcher backlog of 1MB of data to batch)
• Individual tx size throttling via --throttle-tx-size (env var OP_BATCHER_THROTTLE_TX_SIZE): 300 (estimated compressed bytes)
• Block size throttling via --throttle-block-size (env var OP_BATCHER_THROTTLE_BLOCK_SIZE): 21_000 (estimated total compressed bytes, at least 70 transactions per block of up to 300 compressed bytes each)
• Block size throttling that's always active via --throttle-always-block-size (env var OP_BATCHER_THROTTLE_ALWAYS_BLOCK_SIZE): 130_000
  • This block size limit is enforced on the sequencer at all times, even if there isn't any backlog in the batcher. Normal network usage shouldn't be impacted by this. This is to prevent a too fast build up of data to batch.

If the batcher at startup has throttling enabled and the sequencer's op-geth instance to which it's talking doesn't have the miner_setMaxDASize RPC enabled, it will fail with an error message like:

lvl=warn msg="Served miner_setMaxDASize" reqid=1 duration=11.22µs err="the method miner_setMaxDASize does not exist/is not available"
In this case, make sure the miner API namespace is enabled for the correct transport protocol (HTTP or WS), see next paragraph.

The new RPC miner_setMaxDASize is available in op-geth since v1.101411.1. It has to be enabled by adding the miner namespace to the correct API flags, like

GETH_HTTP_API: web3,debug,eth,txpool,net,miner
GETH_WS_API: debug,eth,txpool,net,miner

It is recommended to add it to both, HTTP and WS.

Global options

active-sequencer-check-duration

The duration between checks to determine the active sequencer endpoint. The default value is 2m0s.

altda.da-server

HTTP address of a DA Server.

altda.da-service

Use DA service type where commitments are generated by Alt-DA server. The default value is false.

altda.enabled

Enable Alt-DA mode Alt-DA Mode is a Beta feature of the MIT licensed OP Stack. While it has received initial review from core contributors, it is still undergoing testing, and may have bugs or other issues. The default value is false.

altda.get-timeout

Timeout for get requests. 0 means no timeout.

altda.max-concurrent-da-requests

Maximum number of concurrent requests to the DA server.

altda.put-timeout

Timeout for put requests. 0 means no timeout.

altda.verify-on-read

Verify input data matches the commitments from the DA storage service.

approx-compr-ratio

The approximate compression ratio (<=1.0). Only relevant for ratio compressor. The default value is 0.6.

batch-type

The batch type. 0 for SingularBatch and 1 for SpanBatch. The default value is 0 for SingularBatch.

check-recent-txs-depth

Indicates how many blocks back the batcher should look during startup for a recent batch tx on L1. This can speed up waiting for node sync. It should be set to the verifier confirmation depth of the sequencer (e.g. 4). The default value is 0.

compression-algo

The compression algorithm to use. Valid options: zlib, brotli, brotli-9, brotli-10, brotli-11. The default value is zlib.

compressor

The type of compressor. Valid options: none, ratio, shadow. The default value is shadow.

data-availability-type

The data availability type to use for submitting batches to the L1. Valid options: calldata, blobs, and auto. The default value is calldata.

fee-limit-multiplier

The multiplier applied to fee suggestions to put a hard limit on fee increases. The default value is 5.

hd-path

The HD path used to derive the sequencer wallet from the mnemonic. The mnemonic flag must also be set.

l1-eth-rpc

HTTP provider URL for L1.

l2-eth-rpc

HTTP provider URL for L2 execution engine. A comma-separated list enables the active L2 endpoint provider. Such a list needs to match the number of rollup-rpcs provided.

log.color

Color the log output if in terminal mode. The default value is false.

log.format

Format the log output. Supported formats: 'text', 'terminal', 'logfmt', 'json', 'json-pretty'. The default value is text.

log.level

The lowest log level that will be output. The default value is INFO.

log.pid

Show PID in the log.

max-blocks-per-span-batch

Maximum number of blocks to add to a span batch. Default is 0 (no maximum).

max-channel-duration

The maximum duration of L1-blocks to keep a channel open. 0 to disable. The default value is 0.

max-l1-tx-size-bytes

The maximum size of a batch tx submitted to L1. Ignored for blobs, where max blob size will be used. The default value is 120000.

max-pending-tx

The maximum number of pending transactions. 0 for no limit. The default value is 1.

metrics.addr

Metrics listening address. The default value is 0.0.0.0.

metrics.enabled

Enable the metrics server. The default value is false.

metrics.port

Metrics listening port. The default value is 7300.

mnemonic

The mnemonic used to derive the wallets for either the service.

network-timeout

Timeout for all network operations. The default value is 10s.

num-confirmations

Number of confirmations which we will wait after sending a transaction. The default value is 10.

altda.da-server

HTTP address of a DA Server.

altda.da-service

Use DA service type where commitments are generated by altda server. The default value is false.

altda.enabled

Enable altda mode. The default value is false.

altda.verify-on-read

Verify input data matches the commitments from the DA storage service. The default value is true.

poll-interval

How frequently to poll L2 for new blocks. The default value is 6s.

pprof.addr

pprof listening address. The default value is 0.0.0.0.

pprof.enabled

Enable the pprof server. The default value is false.

pprof.path

pprof file path. If it is a directory, the path is {dir}/{profileType}.prof.

pprof.port

pprof listening port. The default value is 6060.

pprof.type

pprof profile type. One of cpu, heap, goroutine, threadcreate, block, mutex, allocs.

private-key

The private key to use with the service. Must not be used with mnemonic.

resubmission-timeout

Duration we will wait before resubmitting a transaction to L1. The default value is 48s.

rollup-rpc

HTTP provider URL for Rollup node. A comma-separated list enables the active L2 endpoint provider. Such a list needs to match the number of l2-eth-rpcs provided.

rpc.addr

rpc listening address. The default value is 0.0.0.0.

rpc.enable-admin

Enable the admin API. The default value is false.

rpc.port

rpc listening port. The default value is 8545.

safe-abort-nonce-too-low-count

Number of ErrNonceTooLow observations required to give up on a tx at a particular nonce without receiving confirmation. The default value is 3.

sequencer-hd-path

DEPRECATED: The HD path used to derive the sequencer wallet from the mnemonic. The mnemonic flag must also be set.

signer.address

Address the signer is signing transactions for.

signer.endpoint

Signer endpoint the client will connect to.

signer.header

Headers to pass to the remote signer. Format key=value.
Value can contain any character allowed in an HTTP header.
When using env vars, split multiple headers with commas.
When using flags, provide one key-value pair per flag.

signer.tls.ca

tls ca cert path. The default value is tls/ca.crt.

signer.tls.cert

tls cert path. The default value is tls/tls.crt.

signer.tls.key

tls key. The default value is tls/tls.key.

stopped

Initialize the batcher in a stopped state. The batcher can be started using the admin_startBatcher RPC. The default value is false.

sub-safety-margin

The batcher tx submission safety margin (in #L1-blocks) to subtract from a channel's timeout and sequencing window, to guarantee safe inclusion of a channel on L1. The default value is 10.

target-num-frames

The target number of frames to create per channel. Controls number of blobs per blob tx, if using Blob DA. The default value is 1.

throttle-always-block-size

The total DA limit to start imposing on block building at all times.

throttle-block-size

The total DA limit to start imposing on block building when we are over the throttle threshold.

throttle-interval

Interval between potential DA throttling actions. Zero disables throttling.

throttle-threshold

Threshold on pending-blocks-bytes-current beyond which the batcher instructs the
block builder to start throttling transactions with larger DA demands.

throttle-tx-size

The DA size of transactions at which throttling begins when we are over the throttle threshold.

txmgr.fee-limit-threshold

The minimum threshold (in GWei) at which fee bumping starts to be capped. Allows arbitrary fee bumps below this threshold. The default value is 100.

txmgr.min-basefee

Enforces a minimum base fee (in GWei) to assume when determining tx fees. 1 GWei by default. The default value is 1.

txmgr.min-tip-cap

Enforces a minimum tip cap (in GWei) to use when determining tx fees. 1 GWei by default. The default value is 1.

txmgr.not-in-mempool-timeout

Timeout for aborting a tx send if the tx does not make it to the mempool. The default value is 2m0s.

txmgr.receipt-query-interval

Frequency to poll for receipts. The default value is 12s.

txmgr.send-timeout

Timeout for sending transactions. If 0 it is disabled. The default value is 0s.

wait-node-sync

Indicates if, during startup, the batcher should wait for a recent batcher tx on L1 to finalize (via more block confirmations). This should help avoid duplicate batcher txs. The default value is false.

Miscellaneous

help

Show help. The default value is false.

version

Print the version. The default value is false.