Tiered Storage

Crystalline divides indexes into 3 tiers:

• Hot tier: Index data that is frequently accessed
• Warm tier: Index data that is less frequently accessed but still needs to be available for search
• Cold tier: Index data that is rarely accessed

Crystalline will use directories under the /data mountpint to store index data. The default configuration uses the following directory structure:

/data
├── hot
│   ├── index_a
│   └── index_b
├── warm
│   ├── index_a
│   └── index_b
└── cold
    ├── index_a
    └── index_b

If you want to use different storage for each of these tiers, then instead of attaching storage to /data, you can instead attach it to the appropriate hot, warm, or cold directory.