Internal

Category overview

Internal Hard Disk Drives remain the most cost-effective way to add bulk storage to a desktop or NAS (Network Attached Storage). The mechanical design and rated workload class still matter, even after years of refinement. Picking the right tier extends drive life and avoids data loss in multi-drive systems.

What this category covers

3.5-inch SATA HDDs in desktop, NAS, surveillance and enterprise tiers, and 2.5-inch SATA HDDs for notebooks and small chassis. Capacities run from a few hundred gigabytes to over 20 TB depending on the tier.

How to choose an internal hard drive

Pick the workload tier

Desktop drives are tuned for typical eight-hour-day office and home use. NAS drives are rated for 24/7 multi-bay operation with vibration tolerance. Surveillance drives are tuned for continuous video write workloads. Enterprise drives have the longest warranties and highest workload ratings, with corresponding price.

Confirm Conventional or Shingled recording

Conventional Magnetic Recording (CMR) drives perform consistently and rebuild quickly in RAID (Redundant Array of Independent Disks). Shingled Magnetic Recording (SMR) drives are slower at sustained writes and can interact badly with RAID parity rebuilds. For NAS and RAID, choose CMR. For pure archive use, SMR is acceptable and cheaper.

Match RPM and cache to expectations

5400 RPM drives are quieter, run cooler and use less power. 7200 RPM drives are faster, particularly for sequential reads. Cache size (typically 64 to 512 MB) matters for short bursts of mixed work. None of this changes the basic order of magnitude difference between any HDD and any SSD.

Plan for redundancy

Single-drive setups should always have backups. Multi-drive setups should use a RAID level appropriate to the data: RAID 1 for two-drive setups where redundancy is the priority, RAID 5 for 4 to 5 bays, RAID 6 for larger arrays where two-drive failures must be survivable.

Key features to compare

Capacity per drive

Modern 3.5-inch HDDs reach 22 TB and beyond. The largest drives have the lowest cost per gigabyte but lengthen RAID rebuild times significantly, which raises the risk window during a failure. For larger arrays, slightly smaller drives are sometimes the safer choice.

Workload rating in TB written per year

Drive specifications now include an annual workload rating. Desktop drives are usually rated for 55 TB per year; NAS drives for 180 TB; enterprise drives for 550 TB or more. Match the rating to the expected use.

What to check before buying

• Is the drive a CMR or SMR design, and does the use case demand CMR?
• Is the workload tier matched to the install (desktop, NAS, surveillance, enterprise)?
• Does the host have the right SATA port count and the cabling for it?
• For RAID arrays, is a hot spare or a same-tier replacement available?
• Is a backup plan in place beyond the single drive or array?

Frequently asked questions

Are 7200 RPM drives much faster than 5400 RPM drives?

For sequential read and write, 7200 RPM drives are noticeably faster, often by 30 to 40 percent. For random access, the difference is smaller. For most office and backup workloads, either speed is fine. The decisive performance difference is between any HDD and any SSD, not between HDD speeds.

Why are NAS drives more expensive than desktop drives of the same capacity?

NAS drives are rated for 24/7 operation, include vibration tolerance for multi-drive bays, and ship with longer warranties and higher workload ratings. The price difference reflects the longer expected life and the support for multi-drive use, not better raw performance.

Should I buy a Helium-filled HDD?

Helium-filled drives use less power, run cooler and reach higher capacities by allowing more platters in the same case height. They cost slightly more but are now the standard at the highest capacities. For typical NAS and enterprise use, helium drives are a sensible default.

Can I mix drive sizes in a RAID array?

Most RAID levels treat the array as bound by the smallest drive. A larger drive in a mixed array contributes only the size of the smallest drive, with the rest unused. For best capacity utilization, all drives in an array should be the same size and ideally the same model.

How do I move data from an old HDD to a new one?

Use a disk cloning tool to image the old drive to the new one, or back up and restore the data. For boot drives, cloning is faster but requires the new drive to be at least as large as the data on the old one. For arrays, the RAID controller's expansion or replacement function handles the move drive by drive.