Ethereum Virtual Machine (EVM) vs Traditional Operating Systems: A Simple Guide (Part 3)

Welcome back to the final chapter of our Ethereum Virtual Machine (EVM) deep dive. So far, we’ve explored Part 1 and Part 2, how the EVM stacks up against traditional OS sandboxes and why its design shapes decentralized applications. Now, it’s time to crack open the mechanics of gas, storage, and efficiency on Ethereum — key ingredients to building better smart contracts.

Why Does Gas Matter?

Ethereum runs on gas, plain and simple. Every action, whether it’s transferring tokens or interacting with smart contracts, needs gas to get from point A to point B. And just like a car on the road, the more complex the journey (more contract operations), the more fuel (gas) you burn.

Understanding Gas: The Backbone of Ethereum

Imagine gas as Ethereum’s toll system. You pay for every computation your contract makes. If you run out of gas mid-operation, the transaction fails. Think of it as your car breaking down halfway through a trip because the tank ran empty.

Gas Costs: The Hidden Pain of Developers and Users

Gas is more than just a small annoyance for users. High gas fees can make your decentralized application (dApp) expensive, alienating users. From a developer’s perspective, inefficient code not only wastes gas but creates hurdles for adoption and scalability.

Let’s break it down. Why does gas efficiency matter?

Three Key Gas Optimization Strategies

1. Minimizing State Changes

Modifying the state is one of the most expensive things you can do in Ethereum because it involves writing data to the blockchain. Aim to batch state changes wherever possible.

Example: Instead of updating user balances every time a transaction happens, accumulate these updates and make one final state change at the end. This reduces gas by consolidating multiple operations into a single write.

Analogy: Think of it like closing your cash register at the end of the day rather than ringing up each sale as it happens. Fewer entries, less work.

2. Efficient Function Design

The structure of your functions matters more than you think. Large loops or excessive calls inside a single function can eat up gas fast. Using call data instead of memory for function inputs can also help save gas.

Pro Tip: Avoid unnecessary looping. Breaking down large operations into smaller, more manageable chunks will minimize gas consumption.

3. Stay Updated with Solidity

Solidity’s new versions often include gas optimizations under the hood. Keeping your smart contract code updated is a low-effort way to reap these efficiency rewards.

Storage: On-Chain vs. Off-Chain

One of the biggest decisions you’ll make as a developer is where to store your data — on-chain or off-chain. On-chain storage is secure and immutable, but it comes at a premium. Meanwhile, off-chain storage offers cost benefits but sacrifices some transparency.

On-Chain Storage in EVM: How is Data Physically Stored?

One of the fundamental differences between the Ethereum Virtual Machine (EVM) and traditional operating systems is how they handle storage, particularly on-chain data. In a traditional OS, data is typically stored in local file systems, databases, or external storage drives, which are structured in a hierarchical directory tree. By contrast, the EVM operates on a decentralized network of nodes, with each node contributing to the collective ledger of data.

So, how is EVM data physically stored on the node, and how does that differ from traditional OS storage?

Data Structure in EVM

In Ethereum, all on-chain data is stored in key-value pairs using Merkle Patricia Trie (MPT). This cryptographic data structure helps verify the integrity of transactions and states efficiently. Unlike a traditional OS where files are stored in folders, Ethereum stores everything in a shared global state where each contract and account has an associated state root, mapping directly to its data on the blockchain.

• State Trie: The EVM keeps track of the entire state of the system using a structure called the “state trie.” Each account or contract has its own unique address, and this trie is used to track balances, contract code, and storage variables. Each node in the Ethereum network has a copy of the State Trie, and this trie is updated every time a new transaction is executed, such as when ether is sent or when smart contract code is called.

• Storage Trie: Each smart contract or account has its own storage trie. When a contract stores data, such as token balances or critical contract variables, that data is saved in this storage trie, which is unique to that specific contract address.

This structure is highly efficient for decentralized systems but significantly different from how traditional OS storage works. In traditional OS storage, data retrieval and updates are faster and more direct due to centralized access.

Physical Storage on Ethereum Nodes

When you deploy a smart contract or store any data on the blockchain, that information is propagated across all full nodes in the Ethereum network. Each full node keeps a copy of the blockchain, which includes transaction data, the state trie, and storage tries for every account. This data is stored physically on hard drives or SSDs of the nodes, but unlike a traditional OS that stores files locally for private use, blockchain data is replicated across thousands of nodes globally.

• Distributed Nature: Traditional OS data is usually centralized, stored on a local machine or a specific server. In contrast, EVM data is decentralized and replicated across many Ethereum nodes. Each node has a copy of the same data, ensuring redundancy and security.

• Immutable and Public: Once data is written to the blockchain, it becomes immutable and public. While traditional OS systems allow for private data storage with the option to modify or delete files, EVM data is permanent and cannot be tampered with.

• Use Cases: Token balances, critical contract data.

• Example: An ERC-20 token’s balance mapping is stored on-chain to maintain transparency and security.

Gas Cost: Each storage write can consume up to 20,000 gas.

Analogy: Think of it as renting a safe deposit box. It’s secure and accessible, but space is limited, and the cost is high.

Off-Chain Storage

Data that doesn’t require on-chain storage can be offloaded to cheaper solutions like IPFS or Arweave. These systems provide decentralized storage without clogging up Ethereum’s space, but you’ll need to store a reference (hash) on-chain to access it.

• Use Cases: Large files, media, or non-critical data.

• Example: An NFT’s artwork is stored off-chain, with the hash on-chain as a reference.

Gas Cost: A fraction of the cost of on-chain storage since you’re only saving a hash.

Analogy: Imagine storing your photo albums in the attic and just keeping a note of where they are—safe but cost-effective.

Practical Tips for Developers: Boosting Efficiency in Smart Contracts

1. Batch Transactions

Instead of processing each transaction individually, consider batching them. This approach can reduce gas consumption by consolidating multiple operations into a single call.

Example: A payout contract can batch payments, processing multiple users’ payouts in one function call.

2. Leverage Solidity Libraries

Solidity’s built-in libraries, such as SafeMath, ReentrancyGuard, ECDSA, Strings, and SafeCast, offer optimized solutions that reduce gas and improve security.

3. Avoid Redundancy

Functions that perform repetitive checks or unnecessary operations can become a gas sink. Streamline your logic to ensure efficiency.

Example: A function that checks the same condition multiple times can consolidate checks at the start, reducing computational load.

Real-World Case Study: Optimizing a Crowdfunding Contract

Consider a crowdfunding contract where users contribute funds and can claim refunds if the project goal isn’t met.

In the initial design:

• Each contribution updates the contract’s total funds (on-chain).

• Refunds are processed individually, involving multiple state changes.

The Problem

• Frequent updates to the contract’s state lead to excessive gas costs.

• Processing refunds for each contributor adds further complexity.

The Optimization

• Instead of updating the total funds after every contribution, batch the updates at the end of the campaign.

• Process refunds in a single transaction for all users, minimizing costly state changes.

Conclusion: Balancing Gas, Storage, and Efficiency for Smarter dApps

The EVM’s decentralized nature means that all storage is distributed across multiple nodes, relying on cryptographic structures to ensure security and immutability. In contrast, traditional OS storage systems are centralized, faster, and more flexible, but they don’t offer the same level of decentralization or trustlessness. As a developer, understanding how EVM handles data storage can help you design smarter, more efficient contracts while minimizing gas costs, an essential factor for building scalable decentralized applications.

Remember, gas is finite, storage is costly, and efficiency is key. Keep these factors in mind, and you’ll create decentralized applications that are not only scalable but also sustainable in the long run.

External Links For Reference and Further Studies

• For a deeper dive into how Ethereum’s gas system functions, check out the official Ethereum gas documentation.

• Keeping your contracts up to date with the latest version of Solidity can significantly reduce gas consumption. Learn more in the Solidity official documentation.

• For more information on how off-chain storage solutions like IPFS can reduce on-chain gas costs, visit the IPFS website.

• To ensure your smart contract is secure and gas-efficient, check out ConsenSys’ Smart Contract Best Practices.