Solana 기초
Understanding Solana Accounts
A comprehensive guide to Solana's account model—the foundation for understanding tokens, NFTs, and all on-chain data storage.
What You'll Learn
- How Solana accounts differ from Ethereum accounts
- Account ownership and the program model
- Rent and rent exemption
- Types of accounts you'll encounter in token development
Prerequisites
- Basic blockchain understanding
- Solana CLI installed (for examples)
The Solana Account Model
On Solana, everything is an account. Unlike Ethereum where contracts have their own storage, Solana separates code (programs) from data (accounts).
┌─────────────────────────────────────────────┐
│ Account │
├─────────────────────────────────────────────┤
│ lamports: 1000000 │ ← Balance (in lamports, 1 SOL = 1B lamports)
│ data: [bytes...] │ ← Arbitrary data storage
│ owner: 11111111111111111111111111111111 │ ← Program that controls this account
│ executable: false │ ← Is this a program?
│ rent_epoch: 123 │ ← Rent tracking
└─────────────────────────────────────────────┘
Key Concepts
| Concept | Description |
|---|---|
| Lamports | The balance in the smallest unit (1 SOL = 1,000,000,000 lamports) |
| Data | Arbitrary bytes stored in the account |
| Owner | The program ID that can modify this account's data |
| Executable | Whether this account contains program code |
Account Ownership
Every account has an owner—a program that has exclusive rights to:
- Modify the account's data
- Debit lamports from the account
- Change the account's owner (transfer ownership)
The System Program
The System Program (11111111111111111111111111111111) owns all basic wallet accounts:
# View a wallet account
solana account <YOUR_WALLET_ADDRESS>
# Output shows:
# Owner: 11111111111111111111111111111111
When you transfer SOL, you're asking the System Program to debit your account.
Program Ownership
When a program creates an account, that program becomes the owner:
┌─────────────────────────────────────────────────────────────┐
│ Token Program owns token-related accounts │
│ │
│ Token Program ──owns──► Mint Account │
│ │ │
│ └──────owns──► Token Account (your token balance) │
│ │
│ Metaplex Token Metadata Program ──owns──► Metadata Account │
└─────────────────────────────────────────────────────────────┘
Types of Accounts
1. Wallet Accounts (System Accounts)
Basic accounts that hold SOL:
# Create a new wallet
solana-keygen new --outfile wallet.json
# This creates a keypair, and when funded, a System Program-owned account
solana airdrop 1
Properties:
- Owner: System Program
- Data: Empty (0 bytes)
- Purpose: Hold SOL, sign transactions
2. Program Accounts
Accounts that contain executable code:
# View a program account
solana account TokenkegQfeZyiNwAJbNbGKPFXCWuBvf9Ss623VQ5DA
# Owner: BPFLoaderUpgradeab1e11111111111111111111111
# Executable: true
Properties:
- Owner: BPF Loader
- Executable: true
- Data: Compiled program bytecode
3. Data Accounts
Accounts that store arbitrary data for programs:
# View a token mint account
solana account <MINT_ADDRESS>
# Owner: TokenkegQfeZyiNwAJbNbGKPFXCWuBvf9Ss623VQ5DA (Token Program)
# Executable: false
# Data: [mint data...]
4. Program Derived Addresses (PDAs)
Special accounts derived deterministically from a program ID and seeds:
PDA = hash(seeds + program_id + "PDA")
Properties:
- No private key (cannot sign transactions)
- Only the deriving program can sign for it
- Deterministic—same inputs always produce same address
See Understanding PDAs for more details.
Accounts in Token Development
When working with Metaplex tools, you'll interact with several account types:
Token Mint Account
Represents the token itself:
┌─────────────────────────────────────────────┐
│ Mint Account │
├─────────────────────────────────────────────┤
│ mint_authority: <pubkey> │ ← Who can mint more
│ supply: 1000000 │ ← Total supply
│ decimals: 9 │ ← Decimal places
│ freeze_authority: <pubkey> │ ← Who can freeze
└─────────────────────────────────────────────┘
Token Account (Associated Token Account)
Holds a user's balance of a specific token:
┌─────────────────────────────────────────────┐
│ Token Account │
├─────────────────────────────────────────────┤
│ mint: <mint_pubkey> │ ← Which token
│ owner: <wallet_pubkey> │ ← Who owns these tokens
│ amount: 500 │ ← Balance
│ state: Initialized │ ← Account state
└─────────────────────────────────────────────┘
Metadata Account (Metaplex)
Stores token/NFT metadata on-chain:
┌─────────────────────────────────────────────┐
│ Metadata Account │
├─────────────────────────────────────────────┤
│ mint: <mint_pubkey> │ ← Associated mint
│ name: "My Token" │
│ symbol: "MTK" │
│ uri: "https://..." │ ← Off-chain metadata
│ creators: [...] │ ← Creator info
│ royalties: 500 (5%) │
└─────────────────────────────────────────────┘
SPL Token Model vs Metaplex Core
The account structure for tokens and NFTs differs significantly depending on the program you use.
SPL Token + Token Metadata uses multiple accounts per asset:
┌──────────────────────────────────────────────────────┐
│ SPL Token Model (3+ accounts per asset) │
│ │
│ Mint Account ← Token definition (82 bytes) │
│ Token Account (ATA) ← Holder's balance (165 bytes)│
│ Metadata Account ← Name, symbol, URI (PDA) │
│ Master Edition ← NFT edition tracking (PDA) │
└──────────────────────────────────────────────────────┘
Each account is owned by a different program, requires its own rent-exempt deposit, and must be managed separately. Transferring an NFT means updating the Token Account; metadata lives in a separate PDA owned by the Token Metadata program.
Metaplex Core collapses everything into a single account:
┌──────────────────────────────────────────────────────┐
│ Core Model (1 account per asset) │
│ │
│ Asset Account │
│ ├── owner: <wallet_pubkey> │
│ ├── name: "My NFT" │
│ ├── uri: "https://..." │
│ └── plugins: [royalties, freeze, burn, ...] │
└──────────────────────────────────────────────────────┘
With Core, ownership, metadata, and extensibility (via plugins) are stored in one account owned by the Core program. This means fewer accounts to create, lower rent costs, and simpler transactions.
| SPL Token + Token Metadata | Metaplex Core | |
|---|---|---|
| Accounts per NFT | 3–4 (mint, token, metadata, edition) | 1 (asset) |
| Rent cost | ~0.01 SOL | ~0.003 SOL |
| Ownership | Token Account tracks balance | Asset account owner field |
| Metadata | Separate PDA | Built into the asset account |
| Extensibility | Token Extensions (Token-2022) | Plugin system |
| Best for | Fungible tokens (SPL) | NFTs and digital assets |
Which should I use?
For NFTs and digital assets, use Metaplex Core — it's simpler, cheaper, and purpose-built. For fungible tokens (currencies, rewards), use the SPL Token program with Metaplex Token Metadata for on-chain metadata.
Rent and Rent Exemption
Accounts must pay rent to exist on Solana. This prevents blockchain bloat.
How Rent Works
- Rent is paid in lamports based on data size
- Accounts that fall below minimum balance are purged
- Rent-exempt accounts pay a one-time deposit and exist forever
Rent Exemption
To be rent-exempt, an account must hold minimum lamports based on its size:
# Check rent-exempt minimum for different sizes
solana rent 0 # Wallet (0 bytes): ~0.00089 SOL
solana rent 82 # Mint Account: ~0.002 SOL
solana rent 165 # Token Account: ~0.0025 SOL
solana rent 679 # Metadata Account: ~0.0056 SOL
Always Rent-Exempt
When creating accounts with Metaplex tools (MPLX CLI, SDKs), the tools automatically calculate and include rent-exempt amounts. You don't need to manually calculate rent.
Recovering Rent
When you close an account, you recover the rent deposit:
# Burning an NFT recovers most of its rent
mplx core burn-asset <ASSET_ADDRESS>
# Returns ~0.00089 SOL
Solana vs Ethereum
Coming from Ethereum? Here are the key differences:
| Aspect | Ethereum | Solana |
|---|---|---|
| Contract storage | Contract stores its own data | Programs are stateless; data in separate accounts |
| Account creation | Implicit (just send to address) | Explicit (must create and fund account) |
| Storage cost | Gas per operation | Rent exemption (one-time deposit) |
| Ownership | Contracts own themselves | Programs own data accounts |
| Balance storage | Single balance field | Separate token accounts per token |
Practical Implications
Token balances: On Ethereum, one contract tracks all balances. On Solana, each holder has a separate token account:
Ethereum:
ERC-20 Contract
└── balances mapping
├── Alice: 100
└── Bob: 50
Solana:
├── Mint Account
├── Alice's Token Account → amount: 100
└── Bob's Token Account → amount: 50
Viewing Accounts
CLI
# View account info
solana account <ADDRESS>
# View in JSON format
solana account <ADDRESS> --output json
# View only data (hex encoded)
solana account <ADDRESS> --output json | jq '.data'
Explorer
Use Solana Explorer or SolanaFM to view accounts visually:
Programmatically
import { createUmi } from '@metaplex-foundation/umi-bundle-defaults'
import { publicKey } from '@metaplex-foundation/umi'
const umi = createUmi('https://api.devnet.solana.com')
const account = await umi.rpc.getAccount(publicKey('YourAddressHere...'))
if (account.exists) {
console.log('Owner:', account.owner)
console.log('Lamports:', account.lamports)
console.log('Data length:', account.data.length)
}
Common Patterns
Why "Account Not Found"?
On Solana, accounts must be explicitly created:
Error: Account does not exist
Cause: The account has never been created, or it was closed/purged
Solution: Create the account first (automatic with most Metaplex operations)
Associated Token Accounts (ATAs)
ATAs are deterministically derived so you don't need to track them:
ATA = derive(wallet_address, mint_address, token_program)
The MPLX CLI and SDKs automatically create ATAs when needed:
# This auto-creates the recipient's ATA if it doesn't exist
mplx toolbox token-transfer <RECIPIENT> <AMOUNT>
Next Steps
- Understanding PDAs - Dive deeper into Program Derived Addresses
- Transaction fundamentals - How transactions work on Solana
- Create a Solana token - Put this knowledge into practice
FAQ
Why do I need to create token accounts?
Unlike Ethereum where a contract tracks balances, Solana requires separate accounts. This enables parallel processing—different accounts can be modified simultaneously.
What happens if my account runs out of rent?
If an account falls below the rent-exempt threshold, it will be purged after some time, and the remaining lamports returned to the owner. Always keep accounts rent-exempt.
Can I close accounts to recover SOL?
Yes! When you burn NFTs or close token accounts, you recover the rent-exempt deposit. This is why burning assets returns SOL.
Why does my wallet show a small balance after minting?
Creating accounts (mint, metadata, token accounts) requires rent-exempt deposits. These are locked in the accounts, not spent.
What's the difference between owner and authority?
- Owner (on-chain): The program that controls the account's data
- Authority (in account data): The wallet that can perform certain actions (like minting)
Example: A Mint Account is owned by the Token Program, but its mint authority is your wallet.