docs: tw634-da-config

docs/launch-arbitrum-chain/02-configure-your-chain/common/data-availability/config-data-availability.mdx

@@ -0,0 +1,40 @@
+---
+title: 'Configure data availability'
+sidebar_label: 'Config data availability'
+description: 'Learn how to configure data availability for Rollup, AnyTrust, and alt-DA for your Arbitrum chain.'
+author: pete-vielhaber
+sme: Jason-W123
+user_story: As a current Arbitrum chain owner, I want to understand how to configure data availability on my chain.
+content_type: get-started
+---
+
+When you launch an <a data-quicklook-from="arbitrum">Arbitrum</a> chain, you set up data availability (DA) during the process. The choice affects how <a data-quicklook-from="transaction">transaction</a> data is stored and accessed for validation, thereby impacting security, costs, and performance.
+
+<a data-quicklook-from="arbitrum-chains">Arbitrum Chains</a> support multiple DA options, allowing you
+to choose based on your needs (e.g., maximum security vs. lower fees).
+
+## Available data availability options
+
+### 1. Rollup mode (Ethereum/Parent chain DA)
+
+This is the default option for chains that demand security. Transaction data is posted to the <a data-quicklook-from="parent-chain">parent chain</a> as calldata or blobs (after [EIP-4844](https://eips.ethereum.org/EIPS/eip-4844)), using Ethereum's DA layer.
+
+- **Config**: Set `arbitrum.DataAvailabilityCommittee` to `false` in your chain config using the [Chain SDK](https://github.com/OffchainLabs/arbitrum-chain-sdk). No extra set up is needed.
+
+### 2. AnyTrust mode
+
+This mode uses an external Data Availability Committee (DAC), which is a group of permissioned nodes that you choose and run, or outsource (<a data-quicklook-from="raas">RaaS</a>). Instead of posting all the data to the parent chain, the batch poster sends a lightweight <a data-quicklook-from="data-availability-certificate">Data Availability Certificate</a> (DACert) signed by a sufficient number of DAC members. The data is stored offchain and provided when needed.
+
+- **Config**: Set `arbitrumDataAvailabilityCommittee` to `true` in the chain config.
+- Deploy Data Availability Servers (DAS) for each DAC member (using Nitro's DAS software).
+- Generate a keyset (BLS public keys + quorum threshold) from DAC members.
+- Register the keyset on the `SequencerInbox` contract post-deployment.
+- Configure nodes (sequencer, <a data-quicklook-from="batch">batch</a> poster, validators) to connect to DAS endpoints (via REST/RPC aggregators).
+
+For a complete, detailed set of instructions on setting up DAC, DAS, and generating keysets refer to [Get started](/launch-arbitrum-chain/02-configure-your-chain/common/data-availability/data-availability-committees/01-get-started.mdx).
+
+### 3. Alternative data availability (Alt-DA)
+
+In this mode, data is posted to an external modular DA network, such as Celestia, using blobs and data availability sampling. Integration happens through a sidecar server and onchain commitments, such as [Blobstream](https://docs.celestia.org/learn/blobstream/) for verification.
+
+- **Config**: use a modified Nitro build that includes [Celestia integration](https://docs.celestia.org/build/stacks/nitro-das-server/), such as the celestia-server sidecar. Set the DA provider in your node flags and adjust your preferences, for example, using Celestia as the main provider with a fallback to AnyTrust or Ethereum. Other DA options, such as [EigenDA](https://github.com/Layr-Labs/nitro) or [Avail](https://docs.availproject.org/da/build-with-avail/deploy-rollup-on-avail/Optimium/arbitrum-nitro/overview), can be added in a similar way.

docs/partials/_glossary-partial.mdx

@@ -3,7 +3,7 @@ partial_type: glossary
 title: 'Arbitrum Glossary Definitions'
 description: 'Comprehensive glossary of Arbitrum terminology and definitions'
 author: anegg0
-last_reviewed: 2026-01-09
+last_reviewed: 2026-02-10
 ---
 
 ### Active Validator {#active-validator}
@@ -109,6 +109,10 @@ Offchain software that receives bids from [Timeboost](/intro/glossary#timeboost)
 
 A group of Arbitrum transactions posted in a single transaction on the [Underlying Chain](/intro/glossary#underlying-chain) into the [Sequencer Inbox](/intro/glossary#sequencer-inbox) by the [Sequencer](/intro/glossary#sequencer).
 
+### Batch Poster {#batch-poster}
+
+The batch poster is an Externally Owned Account (EOA) controlled by the Sequencer. It is responsible for submitting the compressed transaction batches to the Sequencer Inbox contract on the parent chain.
+
 ### Blockchain {#blockchain}
 
 A distributed digital ledger that is used to record transactions and store data in a secure, transparent, and tamper-resistant way, notably in cryptocurrency protocols.

docs/partials/glossary/_batch-poster.mdx

@@ -0,0 +1,7 @@
+---
+title: Batch Poster
+key: batch-poster
+titleforSort: Batch Poster
+---
+
+The batch poster is an Externally Owned Account (EOA) controlled by the Sequencer. It is responsible for submitting the compressed transaction batches to the Sequencer Inbox contract on the parent chain.

sidebars.js

@@ -372,6 +372,11 @@ const sidebars = {
                   label: 'Data availability',
                   collapsed: true,
                   items: [
+                    {
+                      type: 'doc',
+                      id: 'launch-arbitrum-chain/configure-your-chain/common/data-availability/config-data-availability',
+                      label: `Config data availability`,
+                    },
                     {
                       type: 'category',
                       label: 'Data availability committee',

static/glossary.json

@@ -95,6 +95,10 @@
     "title": "Batch",
     "text": "<p>A group of Arbitrum transactions posted in a single transaction on the <a href=\"/intro/glossary#underlying-chain\">Underlying Chain</a> into the <a href=\"/intro/glossary#sequencer-inbox\">Sequencer Inbox</a> by the <a href=\"/intro/glossary#sequencer\">Sequencer</a>.</p>\n"
   },
+  "batch-poster": {
+    "title": "Batch Poster",
+    "text": "<p>The batch poster is an Externally Owned Account (EOA) controlled by the Sequencer. It is responsible for submitting the compressed transaction batches to the Sequencer Inbox contract on the parent chain.</p>\n"
+  },
   "blockchain": {
     "title": "Blockchain",
     "text": "<p>A distributed digital ledger that is used to record transactions and store data in a secure, transparent, and tamper-resistant way, notably in cryptocurrency protocols.</p>\n"