Disk Types (HDD vs SSD vs Surveillance Drives)

Overview

The choice of disk type has a direct impact on:

• Reliability
• Performance
• Lifespan
• Suitability for continuous workloads

In CCTV and other write-heavy systems, using the wrong disk type can lead to:

• Premature failure
• Dropped recordings
• Reduced retention

Core Disk Categories

Hard Disk Drives (HDD)

Traditional mechanical drives using spinning platters.

Characteristics:

• High capacity
• Lower cost per TB
• Slower access times
• Designed for sustained sequential workloads (depending on type)

Best suited for:

• CCTV storage
• Archival storage
• Bulk data

Solid State Drives (SSD)

Flash-based storage with no moving parts.

Characteristics:

• Very fast read/write speeds
• Low latency
• Higher cost per TB
• Limited write endurance (varies by type)

Best suited for:

• Operating systems
• Databases
• High-performance applications

HDD Types (Important Distinction)

Not all HDDs are equal, this is one of the most common real-world mistakes.

Desktop / Consumer Drives

Designed for typical PC use.

Characteristics:

• Light, intermittent workloads
• Lower duty cycle
• Minimal vibration tolerance

Issues in CCTV use:

• Not designed for 24/7 operation
• Increased failure rates under continuous write
• Firmware not optimised for streaming data

Verdict: Not suitable for CCTV or continuous recording systems

Surveillance Drives (CCTV Rated)

Specifically designed for video recording workloads.

Characteristics:

• Optimised for continuous sequential writes
• Firmware tuned for streaming (e.g. ATA streaming commands)
• Better handling of dropped frames vs retries
• Designed for multi-drive environments

Examples:

• WD Purple
• Seagate SkyHawk

Advantages:

• Stable under constant recording
• Reduced risk of frame loss
• Better compatibility with NVRs

Verdict: Recommended standard for CCTV systems

Enterprise Drives

Designed for servers and data centres.

Characteristics:

• High reliability (MTBF ratings)
• Higher vibration tolerance
• Consistent performance under load
• Typically higher cost

Use in CCTV:

• Suitable for large / critical systems
• Often used in high-end VMS deployments

Verdict: Appropriate for large or critical installations

SSD Types (Brief Overview)

While SSDs are not typically used for bulk CCTV storage, they are relevant for system design.

Consumer SSD (TLC / QLC)

• Lower endurance
• Designed for general use
• Can degrade under sustained writes

Not suitable for continuous recording

Enterprise SSD

• Higher endurance ratings (DWPD)
• Designed for sustained write workloads

Use case:

• High-performance recording systems
• Edge analytics systems

Write Workload Considerations

CCTV systems are write-heavy, not read-heavy.

Key characteristics:

• Continuous data stream
• Minimal idle time
• Large sequential writes

This differs significantly from:

• Desktop usage (bursty reads/writes)
• Database workloads (random I/O)

Why Surveillance Drives Matter

Surveillance drives prioritise:

• Write continuity over data recovery

In CCTV:

• Dropped frames are preferable to system stalls
• Retry-heavy behaviour (typical in desktop drives) can cause recording issues

Multi-Drive Systems & Vibration

In RAID/NVR environments:

• Drives are mounted closely together
• Vibration from multiple disks affects performance

Surveillance and enterprise drives include:

• Rotational vibration sensors
• Firmware compensation

Consumer drives typically do not.

Capacity vs Performance

Larger drives:

• Increase rebuild time (RAID impact)
• Increase risk during failure events
• May reduce overall system resilience if poorly designed

Common Mistakes

1. Using Desktop Drives in NVRs

Leads to early failure and unstable recording.

2. Choosing Based on Price per TB Alone

Lower cost often comes with reduced reliability.

3. Ignoring Workload Ratings

Drives are designed for specific duty cycles.

4. Mixing Drive Types

Different firmware and performance characteristics can cause:

• Inconsistent RAID behaviour
• Reduced reliability

Practical Guidance

• Use surveillance-rated drives for CCTV systems
• Use enterprise drives for large or critical deployments
• Avoid consumer HDDs for continuous recording
• Size systems with RAID and rebuild behaviour in mind

Summary

Disk selection is a critical part of system design.

For CCTV systems:

• The workload is continuous and write-heavy
• Standard consumer drives are not suitable
• Surveillance or enterprise-grade drives should be used

Correct disk selection improves:

• Reliability
• Recording stability
• System lifespan