TieredStore Stress Tests

Stress tests for the two-tier hot/cold storage system with automatic data migration.

Test Suite

Results

Running

# Run all TieredStore stress tests
cargo test --release -p stress_tests --test tiered_store_stress -- --ignored --nocapture

# Run specific test
cargo test --release -p stress_tests stress_tiered_hot_only_scale -- --ignored --nocapture

Hot-Only Scale Test

Tests TieredStore performance with only hot tier active (no cold storage).

What it validates:

• In-memory performance at scale
• DashMap + instrumentation overhead
• Memory usage patterns

Expected behavior:

• Throughput > 500K entities/sec
• Linear memory growth
• Consistent latency distribution

Migration Under Load

Tests hot-to-cold data migration while concurrent reads/writes continue.

What it validates:

• Migration correctness during active use
• No data loss during tier transitions
• Read consistency during migration

Expected behavior:

• All data accessible before and after migration
• Reads don’t block on migration
• Writes to migrated keys work correctly

Hot Read Latency

Tests random access read latency for hot tier data.

What it validates:

• Read latency distribution
• Hot path optimization
• Cache efficiency

Expected behavior:

• p50 latency < 3us
• p99 latency < 500us
• No extreme outliers (p999 < 10ms)

Architecture

TieredStore
    │
    ├── Hot Tier (DashMap)
    │   ├── Fast in-memory access
    │   ├── Access instrumentation
    │   └── Automatic hot shard tracking
    │
    └── Cold Tier (mmap)
        ├── Disk-backed storage
        ├── Memory-efficient for large datasets
        └── Transparent promotion on access

Migration Strategies

Configuration

#![allow(unused)]
fn main() {
let config = TieredConfig {
    cold_dir: PathBuf::from("/var/lib/neumann/cold"),
    cold_capacity: 1_000_000,  // Max cold entries
    sample_rate: 0.01,         // 1% access sampling
};
}