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When choosing between 7200 RPM SATA and 15000 RPM SAS hard drives, developers need to consider several performance metrics:

• Rotational Speed: 15k drives complete more rotations per minute, reducing latency.
• Interface: SAS typically offers full duplex communication vs SATA's half duplex.
• Workload Suitability: 15k SAS excels in random I/O scenarios common in databases.

Here's a Python script to benchmark disk performance using the subprocess module:

import subprocess

def benchmark_disk(device):
    # Test sequential read speed
    cmd = f"hdparm -tT {device}"
    result = subprocess.run(cmd.split(), capture_output=True, text=True)
    print(result.stdout)
    
    # Test random access
    cmd = f"ioping -c 10 {device}"
    result = subprocess.run(cmd.split(), capture_output=True, text=True)
    print(result.stdout)

benchmark_disk("/dev/sda")  # Replace with your device
benchmark_disk("/dev/sdb")  # Replace with your device

Theoretical average latency calculations:

def calculate_latency(rpm):
    return (60 * 1000) / (rpm * 2)  # in milliseconds

print(f"7200 RPM latency: {calculate_latency(7200):.2f} ms")
print(f"15000 RPM latency: {calculate_latency(15000):.2f} ms")

For MySQL configurations, you might see these differences in my.cnf:

# For 7200 RPM SATA (higher queue depth needed)
innodb_io_capacity = 800
innodb_io_capacity_max = 2000

# For 15000 RPM SAS (lower queue depth sufficient)
innodb_io_capacity = 1200
innodb_io_capacity_max = 3000

While 15k SAS drives offer better performance, they come with:

• Higher power consumption (typically 10-12W vs 6-8W for 7.2k)
• Shorter lifespan (1.2M hours MTBF vs 1.5M for enterprise SATA)
• 2-3x higher cost per GB

Choose 15k SAS when:

• Running high-transaction databases (MySQL, PostgreSQL)
• Virtualization hosts with many VMs
• Applications requiring low latency (financial systems)

Choose 7.2k SATA when:

• Budget is constrained
• Workload is sequential (media storage, backups)
• Capacity is more important than IOPS

When comparing 7.2k RPM SATA and 15k RPM SAS drives of the same generation, the performance delta comes down to three key metrics:

// Typical performance characteristics (same generation)
const hddSpecs = {
  sata7200: {
    avgLatency: 4.17ms,
    seekTime: 8-12ms,
    throughput: 120-180MB/s,
    interface: 'SATA III (6Gbps)'
  },
  sas15000: {
    avgLatency: 2.0ms,
    seekTime: 3-5ms,
    throughput: 200-250MB/s,
    interface: 'SAS 12Gbps'
  }
};

For MySQL workloads, the difference becomes particularly noticeable in IOPS-intensive operations:

# MySQL configuration showing 2-3x performance difference
[mysqld]
innodb_io_capacity = 200   # 7.2k SATA
innodb_io_capacity = 500   # 15k SAS

# Benchmark results (TPC-C)
# 7.2k SATA: 1200 transactions/minute
# 15k SAS: 2800 transactions/minute

The 15k SAS drives shine in specific scenarios:

• High-frequency transaction systems (financial applications)
• OLTP databases with random access patterns
• Virtualization hosts with many active VMs

Example of a Cassandra configuration that benefits from SAS:

# cassandra.yaml optimizations for SAS
concurrent_reads: 32
concurrent_writes: 32
disk_optimization_strategy: ssd

While 15k SAS offers better performance, consider these factors:

For cost-sensitive deployments, consider tiered storage approaches:

# Linux LVM configuration example
pvcreate /dev/sda  # 15k SAS for hot data
pvcreate /dev/sdb  # 7.2k SATA for cold data
vgcreate db_vg /dev/sda /dev/sdb
lvcreate -L 500G -n hot_data db_vg /dev/sda
lvcreate -L 2T -n cold_data db_vg /dev/sdb