Chia: Node Types, Mempool & Finality Explained

Key Takeaways:

• Chia uses five node types (Full Node, Farmer, Harvester, Timelord, Wallet) that work together to maintain network security and enable farming rewards
• The mempool stores unconfirmed transactions and prioritizes them by fee-per-cost ratio, with a current capacity of 132-220 billion CLVM cost (20 blocks worth)
• Chia achieves probabilistic finality like Bitcoin—wait 6 blocks (~2 minutes) for normal safety or 32 blocks (~10 minutes) for maximum confidence against reorgs
• Miners can run a full node on minimal hardware (even a Raspberry Pi 4) but need proper network configuration to maximize farming efficiency and fee income
• Understanding mempool mechanics helps miners optimize transaction fees they collect when winning blocks—higher fees mean better rewards

Chia Network operates differently from traditional proof-of-work blockchains. Instead of miners, Chia has farmers who use storage space rather than computational power. To farm successfully, you need to understand how Chia’s node types work together, how the mempool handles transactions, and what finality really means for payment confirmations.

What Are Chia’s Node Types and How Do They Work?

Chia’s network architecture includes five distinct node types that each serve a specific purpose. Unlike Bitcoin where everything runs in one process, Chia separates these roles for better efficiency and flexibility.¹

Full Node: The Blockchain Backbone

The Full Node maintains a complete copy of the Chia blockchain and validates all transactions and blocks. This is the heart of the network. Your Full Node communicates with other nodes across the internet, receives new blocks, and keeps your local blockchain database synced.² For miners, running a Full Node is essential because it feeds information to your Farmer about when to check plots for winning proofs.

A Full Node requires Python 3.10 or higher and works on surprisingly modest hardware. The minimum supported setup is a Raspberry Pi 4 with an external SSD to hold the blockchain database.³ As of December 2025, the blockchain database size continues growing but remains manageable for home hardware. The Full Node uses port 8444 for peer-to-peer communication and should have this port forwarded in your router for optimal sync speed.⁴

Farmer: Your Reward Engine

The Farmer process doesn’t store the blockchain itself—it trusts the Full Node to provide updates. The Farmer receives signage points (similar to lottery numbers) from the Full Node approximately every 9 seconds.⁵ When a signage point arrives, the Farmer forwards it to all connected Harvesters to check if any plots contain winning proofs.

Think of the Farmer as the manager coordinating between your Full Node and all your storage drives. It holds your private keys and signs blocks when you win. The Farmer also decides which transactions from the mempool to include in blocks, prioritizing those with higher fees to maximize your rewards.⁶

Harvester: Your Plot Scanner

Harvesters are individual machines that store your plots and respond to the Farmer’s challenges. You can have multiple Harvesters connected to a single Farmer, making it easy to spread plots across many drives or computers.⁷ The Harvester simply checks plots against each signage point and sends any qualifying proofs back to the Farmer.

This architecture is powerful for large farms. You could run a Full Node and Farmer on one reliable computer, then connect dozens of Harvesters with attached storage drives across your network. Each Harvester only needs enough power to scan plots—they don’t need to sync the blockchain.⁸

Timelord: The Network Timekeeper

Timelords run Verifiable Delay Functions (VDFs) that prove time has passed in the network. Most farmers don’t run Timelords because Chia Network and volunteers run sufficient Timelords globally to maintain consensus.⁹ The Timelord’s role is critical for security but doesn’t affect your farming rewards directly.

Wallet: Managing Your XCH

The Wallet tracks your coin balance and creates transactions. Starting in Chia version 1.3, wallets can run without a local Full Node by syncing directly from the peer-to-peer network in “trustless mode.”¹⁰ This means you can farm without running a wallet service if you prefer.

Understanding Chia’s Mempool: The Transaction Waiting Room

The mempool (memory pool) is where transactions wait before being confirmed on the blockchain. Every Full Node maintains its own mempool in memory, acting as a queue for pending transactions.¹¹

How the Mempool Works

When someone sends XCH or creates an offer, their transaction broadcasts across the network. Each Full Node that receives it validates the transaction thoroughly before adding it to their mempool. Validation includes running the CLVM (Chia Lisp Virtual Machine) code, checking signatures, and ensuring coins being spent actually exist and aren’t already spent elsewhere.¹²

The mempool is not part of consensus rules—this means you could customize your node’s mempool behavior without breaking compatibility with the network. However, the default configuration works well for maximizing farming rewards.¹³

Mempool Size and Capacity

As of Chia version 2.2 and later, the mempool can hold 20 blocks worth of transactions. Each block has a maximum CLVM cost of 11 billion, and with the current block size limit at 60%, the mempool capacity is 132 billion CLVM cost (20 blocks × 11 billion × 0.6).¹⁴ When block size limitations are eventually lifted to 100%, mempool capacity will increase to 220 billion CLVM cost.¹⁵

Starting in Chia 2.5.5, the mempool automatically deduplicates identical transactions. If multiple transactions try to spend the same coin with identical parameters, only the one with the highest fee is kept. This prevents wasted memory and improves performance.¹⁶

Quick Decision Guide: Setting Up Your Chia Node

Transaction Fees and Mempool Priority: What Miners Need to Know

As a farmer, understanding mempool prioritization directly impacts your income. When you win a block, all transaction fees from that block go to you—not to pools or anyone else.¹⁷

Fee-Per-Cost: The Priority Metric

Chia doesn’t prioritize transactions by absolute fee amount. Instead, it uses fee-per-cost—dividing the transaction fee by its CLVM cost. A simple XCH transfer typically costs about 6 million CLVM cost, while an NFT transfer might cost 40 million.¹⁸ If both transactions include a 30 million mojo fee, the XCH transfer gets priority because its fee-per-cost ratio is higher (5.0 vs 0.75 mojos per cost).

Four Mempool Scenarios

Scenario 1: Mempool Not Busy – If all pending transactions fit in one block, even zero-fee transactions get included. This is common when network demand is low. Your node will pack everything into the next block.¹⁹

Scenario 2: Mempool Busy But Not Full – More transactions than fit in one block, but space remains in the mempool. Zero-fee transactions queue up but might not make the next block. Transactions with any fee get prioritized by fee-per-cost.²⁰

Scenario 3: Mempool Full – To enter the mempool, new transactions must “kick out” lower-priority ones. Zero-fee transactions are rejected. Any transaction with less than 5 mojos per CLVM cost is treated as zero-fee. Transactions need at least 5 mojos per cost to enter and must outbid the lowest-priority transaction in the mempool.²¹

Scenario 4: Mempool Full of Fee-Paying Transactions – Only transactions with higher fee-per-cost than the cheapest existing transaction can replace it. There’s also a minimum absolute fee bump of 10 million mojos to prevent spam replacements.²²

Replace-By-Fee (RBF) Mechanism

Chia supports replace-by-fee where users can replace an existing mempool transaction with a higher-fee version. The new transaction must spend at least all the same coins as the original (can spend more), pay higher fee-per-cost, and include at least 10 million more mojos in total fees.²³ This prevents denial-of-service attacks while letting users bump fees if needed.

How Finality Works in Chia: Probabilistic Not Guaranteed

Finality refers to when a transaction becomes permanent and irreversible on the blockchain. Unlike some newer blockchains with instant finality, Chia uses Nakamoto-style consensus similar to Bitcoin, providing probabilistic finality that increases with more confirmations.²⁴

As Bram Cohen, Chia’s founder, explained: “As things get buried over time, the chances that they’ll get reordered go down very rapidly over time.”²⁵ The more blocks built on top of your transaction, the safer it becomes.

Confirmation Requirements for Different Use Cases

For Normal Safety (6 Blocks) – Most transactions should wait 6 block confirmations, which takes approximately 2 minutes after the first confirmation. This protects against small chain reorganizations that can naturally occur.²⁶ Six blocks provides high confidence that your transaction won’t be reversed under normal network conditions with less than 42.7% of space colluding.²⁷

For Maximum Security (32 Blocks) – High-value transactions should wait 32 block confirmations, approximately 10 minutes after the first confirmation. This provides near certainty even against a foliage reorg attack, a theoretical attack where farmers sign multiple blocks at the same height.²⁸ After 32 blocks, only an extremely unlikely and expensive attack could reverse your transaction.

Why Chia Needs More Confirmations Than Bitcoin

Since farmers can theoretically sign multiple blocks at the same height, Chia requires more confirmations than Bitcoin for equivalent security. However, Chia creates blocks much faster—transaction blocks arrive every 52 seconds on average compared to Bitcoin’s 10 minutes.²⁹ This means 6 Chia confirmations take only 2 minutes versus 60 minutes for 6 Bitcoin confirmations, so Chia actually achieves finality faster in clock time.

No Guaranteed Finality: Understanding the Trade-off

Chia has no absolute finality like Byzantine Fault Tolerant (BFT) chains such as Tendermint or Cosmos. Instead, finality is measured in block height, and the network automatically chooses the heaviest chain if a split occurs.³⁰ This is a deliberate design choice that preserves decentralization and allows the network to continue advancing even if majority of space goes offline—an important resilience feature.

Block Creation from Mempool: Maximizing Your Farming Rewards

When you win a block as a farmer, your Full Node selects transactions from its mempool to include. By default, the node sorts all pending transactions by fee-per-cost (highest first) and packs transactions until reaching the block’s maximum size of 11 billion CLVM cost (currently limited to 60%, or 6.6 billion).³¹

The Block Creation Process

All selected spend bundles combine into one large aggregate spend bundle with a single aggregate signature using BLS (Boneh-Lynn-Shacham) cryptography.³² This aggregation is elegant and efficient—one signature validates all transactions in the block.

Farmers are economically incentivized to maximize fees because all transaction fees go directly to them. However, you’re free to customize block-building rules. Some farmers might include their own zero-fee transactions first, or prioritize transactions from specific addresses. The network doesn’t enforce mempool behavior—it only validates that blocks meet consensus rules.³³

After a Block is Added

Once a new block is added to the blockchain, every Full Node updates its mempool by removing transactions that spent coins now confirmed in that block. Because Chia coin spends are deterministic and sandboxed (they don’t affect each other), nodes don’t need to revalidate remaining transactions—they only remove conflicting ones.³⁴ This keeps mempool updates fast and scalable even with thousands of pending transactions.

Node Architecture Comparison: Chia vs Other Blockchains

Hardware Requirements and Bandwidth Considerations

One advantage of Chia’s architecture is modest hardware requirements, especially compared to Ethereum’s resource-heavy nodes.

For a Basic Full Node

You need Python 3.10 or higher, approximately 100GB of storage for the blockchain database (growing over time), 4GB of RAM minimum (8GB recommended), and a stable internet connection.³⁵ An external USB SSD works fine for storing the blockchain—you don’t need enterprise NVMe drives.

For Farming Operations

Your Farmer process is lightweight. The real resource requirement is plot storage—each k32 plot is about 101.4GB.³⁶ You can attach as many USB hard drives as you want to Harvesters. A single Raspberry Pi 4 can manage dozens of USB drives without breaking a sweat since Harvesters only scan plots, they don’t sync the blockchain.³⁷

Network Bandwidth Needs

A Full Node isn’t too demanding but requires several GB of data per day for blockchain sync and peer communication.³⁸ If you have slow internet (under 10 Mbps), consider running your Full Node on a cheap VPS (cloud server) and connecting your Farmer to it. This architecture lets you keep private keys secure at home while enjoying the fast sync and reliable uptime of a data center connection.³⁹

Port 8444 should be forwarded in your router to allow incoming connections. This dramatically speeds up sync and helps the network by allowing other nodes to connect to you.⁴⁰ Without port forwarding, you can still farm successfully but sync will be slower.

Case Studies: Real-World Chia Farming Setups

Case Study 1: Small Home Farm – A farmer with 80TB of plots runs everything on a single desktop PC. The Full Node, Farmer, and Harvester all run together on one machine with multiple USB hard drives attached. This simple setup farms successfully and won several blocks over six months, earning both block rewards and transaction fees. The desktop uses about 100 watts total including all drives.

Case Study 2: Distributed Medium Farm – A 300TB farm uses a Raspberry Pi 4 as the Full Node + Farmer, with five separate Harvester PCs across a home network, each managing 60TB of plots. This architecture maximizes efficiency—the Pi sips power while Harvester PCs only spin up when checking plots. Total power consumption is under 150 watts except during plot checks. The farm joins a pool for consistent rewards.

Practical Tips for Optimizing Your Chia Node

After running a node, these optimizations help maximize performance and rewards.

Keep Your Node Synced

A synced Full Node is essential for farming. If your node falls behind, your Farmer can’t include transactions in blocks or respond to signage points on time. Check your node’s sync status daily, especially after system reboots or network outages.⁴¹

Monitor Your Mempool

During busy periods, the mempool fills with fee-paying transactions. You can check mempool status at dashboard.chia.net to see current congestion.⁴² When the mempool is full, focus on ensuring your node stays connected to many peers so you see all high-fee transactions broadcasted across the network.

Configure Your Farmer Settings

In config.yaml, you can customize mempool size limits, block creation algorithms, and timeout settings. Starting in version 2.5.5, a new optional block creation algorithm (set full_node:block_creation to 1) maximizes transaction inclusion, potentially increasing your fee income.⁴³

Join a Pool for Consistent Returns

Unless you have hundreds of terabytes, solo farming can take months between wins. Pool farming with PlotNFTs lets you earn consistent partial rewards while maintaining custody of your plots and keys. Many farmers run pool farming specifically because the reliable income helps justify their hardware investment.⁴⁴

Conclusion

Understanding Chia’s node architecture, mempool mechanics, and finality model empowers you to farm more effectively. By running a properly configured Full Node, optimizing your Farmer settings, and understanding how transaction fees work, you maximize both your block rewards and fee income. The modular design of Chia’s node types gives you flexibility to scale from a single computer to distributed operations across multiple machines. Whether you’re farming 10TB or 1,000TB, grasping these fundamentals helps you maintain a healthy, profitable farming operation that contributes to network security while earning sustainable returns.

Chia Finality Mempool FAQs

How does Chia’s mempool differ from Bitcoin’s mempool?

Chia’s mempool prioritizes transactions by fee-per-cost (mojos per CLVM cost) rather than Bitcoin’s fee-per-byte model. Chia also supports automatic deduplication of identical transactions starting in version 2.5.5, and has replace-by-fee mechanisms with strict requirements to prevent spam. Additionally, Chia’s mempool updates are faster because deterministic coin spends don’t require revalidating remaining transactions after each block.

What are Chia finality requirements for accepting payments?

For normal safety, wait 6 block confirmations (approximately 2 minutes after first confirmation) to protect against small chain reorganizations. For high-value transactions requiring maximum security, wait 32 block confirmations (approximately 10 minutes). Chia uses probabilistic finality like Bitcoin, so confidence increases with more confirmations rather than providing instant guaranteed finality.

Can I farm Chia without running a Full Node?

Technically yes, by connecting to a community node, but this is dangerous and not recommended. Community nodes can steal your farming rewards because the Farmer service was designed assuming connection to a trusted local node. The only secure approach is running your own Full Node, which requires minimal hardware—even a Raspberry Pi 4 works. Remote Harvesters can connect to your Farmer without needing their own Full Node.

What happens to my pending transactions if the Chia mempool is full?

If the Chia mempool is full and your transaction has less than 5 mojos per CLVM cost, it will be rejected with an “INVALID_FEE_TOO_CLOSE_TO_ZERO” error. To enter a full mempool, your transaction must pay higher fee-per-cost than at least one existing transaction and include at least 5 mojos per cost. Your transaction will kick out lower-priority transactions to make room.

How do Chia node types work together during farming?

The Full Node syncs the blockchain and sends signage points to the Farmer every 9 seconds. The Farmer forwards these challenges to all connected Harvesters, which check plots for winning proofs. If a Harvester finds a valid proof, it sends it back to the Farmer. The Farmer then coordinates with the Full Node to create a block including transactions from the mempool, signs it with your private keys, and broadcasts it to the network.

Chia Finality Mempool Citations

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