Storage Proxy vs Logic Proxy: Choosing Your Upgrade Pattern

Storage Proxy (or Diamond/Proxy) excels at gas-efficient, granular upgrades because it separates contract logic from a persistent storage layout. For example, the EIP-2535 Diamond Standard allows a single proxy to delegate calls to multiple logic contracts (facets), enabling targeted function upgrades without migrating state. This pattern is used by protocols like Aave and Uniswap V3 to manage complex, evolving feature sets while keeping storage reads/writes cheap and predictable.

Logic Proxy (or Transparent/UUPS) takes a different approach by embedding upgrade logic directly within the implementation contract. This results in a simpler, more auditable security model with a smaller attack surface, as the proxy itself contains minimal code. The trade-off is that each upgrade requires a full contract swap, which can be more expensive and disruptive for large state migrations. Standards like EIP-1967 and EIP-1822 formalize these patterns, favored for their straightforward deployment and verification on explorers like Etherscan.

The key trade-off: If your priority is modularity and minimized upgrade gas costs for a system with hundreds of functions, choose Storage Proxy. If you prioritize maximized security and simplicity with less frequent, comprehensive upgrades, choose Logic Proxy. Your decision ultimately hinges on whether you value architectural flexibility over operational simplicity.

Storage Proxy excels at minimizing deployment complexity and gas costs for straightforward upgrades. By separating the contract's data storage from its logic, you can deploy new logic contracts without migrating state, saving significant gas—often 50-90% compared to a full storage migration. For example, protocols like Aave and Compound use this pattern for their lending pools, enabling seamless upgrades to interest rate models or oracle integrations without moving billions in TVL. The trade-off is that the proxy's storage layout is permanently fixed, limiting future architectural changes.

Logic Proxy (or Transparent/UUPS Proxy) takes a different approach by embedding upgrade logic directly within the implementation contract itself, as defined by EIP-1822 and EIP-1967. This results in a cleaner separation of concerns and reduces the attack surface of the proxy admin. However, it introduces a critical trade-off: each upgrade must be meticulously vetted, as a faulty implementation can brick the proxy. This model is favored by protocols like OpenZeppelin's UUPS standard for its gas efficiency on deployment and its alignment with a more modular, contract-based upgrade authority.

The key trade-off: If your priority is gas-efficient, state-preserving upgrades with a simple, immutable storage layout, choose a Storage Proxy. This is ideal for mature protocols with stable core data structures. If you prioritize maximizing modularity, reducing proxy attack vectors, and accepting stricter upgrade governance, choose a Logic Proxy (UUPS). This suits agile teams building complex, evolving systems where logic separation is paramount. Ultimately, the Storage Proxy offers safety through simplicity, while the Logic Proxy offers flexibility through stricter control.