[DRAFT] SSD TRIM Support

TRIM is essential for SSDs (Solid State Drives) to optimize performance and extend lifespan.

Why is TRIM Important?

• Performance Optimization: TRIM identifies unused data blocks for efficient garbage collection and reduced write amplification. It also maintains consistent write performance and speeds over time.

• Extended Longevity: Reduces wear by minimizing unnecessary write/erase cycles.

• Space Management: Ensures accurate free space tracking for efficient storage.

Use Cases

• Formatting & Mounting: Clears the entire disk, preparing it for new data.

• Defragmentation: Batches TRIM commands to delete obsolete data and optimize performance.

Design

Technical Design

• Flash Memory Basics: SSDs use non-volatile NAND flash memory, with logical-to-physical address mapping via the Flash Translation Layer (FTL).

• Program/Erase Cycles: TRIM accelerates block erasure by marking unused data, supporting wear leveling, and garbage collection.

TRIM Library

• Provides an interface to issue TRIM commands.

• Supports chunked TRIM operations for SAS/SATA disks to avoid timeouts.

• Integrates with SWARM for NVMe disks and other storage types.

SWARM Integration

1. Formatting: SWARM trims disks in chunks during formatting, ensuring readiness for use.

2. Defragmentation: Batches TRIM operations to delete obsolete streams and optimize storage.

Validation and Testing

Validation:

• Use iostat -x to monitor TRIM commands during:

  • Formatting: Confirm the entire disk is trimmed.

  • Defragmentation: Verify delayed TRIM clears marked streams and relocated data.

Testing Checklist:

1. Setup:

   • Enable TRIM (disk.enableSSDTrims = 1) in configuration and reboot.

   • Test on various volumes: regular, encrypted, erasure-coded.

2. Functional Testing:

   • Verify TRIM is issued during formatting and defragmentation.

3. Performance Testing:

   • Measure read/write speeds and latency before and after TRIM.

4. Stress Testing:

   • Validate system stability under prolonged TRIM operations.

5. Mixed Configurations:

   • Test TRIM with SSDs and HDDs in combined setups.

6. Resource Monitoring:

   • Monitor CPU, memory, and logs to detect anomalies during TRIM operations.

Implementation Steps

1. Configuration:

   • Add disk.enableSSDTrims = 1 to node.cfg and reboot.

2. Example for Encrypted Volumes:

   • Update configuration with:

     vols = all:f
     disk.encryptNewVolumes=1
     disk.encryptionKeys={'keyA':'theBestWay'}
     disk.encryptionKeyPrimary=keyA
     disk.enableSSDTrims = 1

3. Verification:

   • Use iostat -x to confirm TRIM activity in discard columns.

By integrating TRIM, SSDs maintain optimal performance, efficient storage management, and extended durability, delivering robust storage solutions.

Limitations

• SWARM does not currently support NVMe SSDs or self-encryption features.

• TRIM functionality is not universally supported across all SSD types.

• Encryption at rest is supported via dm-encrypt.

• NVMe SSD support is under development.