Internal solid state drives (SSDs) and hard disk drives (HDDs) are two types of data storage devices used in computers. They have different physical designs and methods of storing data, leading to performance differences.
What is an internal SSD?
An internal SSD is a solid state drive that is designed to be installed inside a computer. It uses flash memory chips to store data persistently, without any moving parts. Flash memory retains data even when power is removed, unlike regular RAM which loses data when powered off.
SSDs connect to the computer’s motherboard using an interface like SATA or PCIe. This allows the operating system to access it like a regular hard drive. Compared to mechanical hard drives, SSDs are much faster, more reliable, and consume less power.
Advantages of Internal SSDs
- Much faster read and write speeds compared to HDDs, often by 100x or more for large file transfers.
- No mechanical parts and less latency mean vastly better reliability and durability.
- Lower power consumption extends laptop battery life.
- Compact form factor allows smaller computer designs.
- Better optimized for random access workloads due to lack of seek time.
Disadvantages of Internal SSDs
- More expensive per gigabyte compared to HDDs currently.
- Limited number of erase/write cycles per memory cell (although endurance is improving).
- Older drives had issues with performance degradation over time.
What is an internal HDD?
An internal hard disk drive (HDD) is a traditional spinning magnetic media drive designed to be mounted inside a computer. It stores data on quickly rotating platters coated in magnetic material. Read/write heads floating just above the platters can access data anywhere on them.
Internal HDDs connect to the motherboard using SATA, SAS or NVMe interfaces. They have traditionally been the default storage choice for desktop PCs, servers and laptops due to high capacities and low costs per gigabyte.
Advantages of Internal HDDs
- Much cheaper per gigabyte compared to SSDs currently.
- Available in much higher capacities – up to 10TB+ in consumer drives.
- Mature, well-understood technology.
Disadvantages of Internal HDDs
- Slower read/write speeds compared to SSDs due to physical limitations.
- Moving parts lead to higher failure rates with age or shock damage.
- Latency waiting for the read/write heads to move is significant.
- Loud noise and vibration from spinning platters.
- Higher power consumption than SSDs.
- Larger size and form factors.
Internal SSD vs HDD Comparison
Here is a direct comparison between internal SSDs and HDDs:
| Attribute | SSD | HDD |
|---|---|---|
| Read Speeds | Up to 3500MB/s | Up to 200MB/s |
| Write Speeds | Up to 3200MB/s | Up to 150MB/s |
| Latency | Microseconds | Milliseconds |
| Failure Rate | 2.0% over 4 years | 4.6% over 4 years |
| Capacity | Up to 30TB | Up to 20TB |
| Price Per GB | $0.10 – $0.15 | $0.02 – $0.03 |
| Power Usage | 1.5 – 2.5W | 6 – 11W |
| Noise | Silent | Audible |
| Form Factor | 2.5″, M.2 | 3.5″, 2.5″ |
As the table illustrates, SSDs are much faster in terms of bandwidth and latency, more reliable, silent, and power efficient. However, HDDs are cheaper per gigabyte and offer much higher capacities currently.
How do Internal SSDs Work?
Internal SSDs store data on flash memory chips made from silicon wafers. These non-volatile memory chips retain data even when the power is removed. Here are the key components inside an SSD:
- Controller – This is the processor that manages all operations on the SSD. It has an embedded processor, cache and firmware. The controller handles reads/writes, wear leveling, error correction, etc.
- NAND flash memory – The raw flash chips that store the data. Data is saved in an array of memory cells made of floating-gate transistors.
- DRAM cache – High-speed volatile RAM that caches frequently accessed data.
- Firmware – Low-level software that provides the OS interface and manages the flash memory.
When data is written to the SSD, it is spread across the flash chips in parallel to improve speed. The data is also error corrected, encrypted and buffered in the fast DRAM cache. Wear leveling algorithms distribute writes evenly so no cells wear out prematurely.
Flash Memory in SSDs
The NAND flash memory cells in SSDs trap electrons on a floating gate to store data. Each cell has a range of voltage thresholds corresponding to different binary data values. Reads are fast since all cells can be accessed in parallel.
However, erasing cells takes much longer and must be done in blocks, not individually. This is why SSDs slow down when filled close to capacity. More free space is required for efficient writing. Newer 3D NAND flash mitigates this with larger cell blocks.
How do Internal HDDs Work?
Internal hard drives store data magnetically on rapidly spinning circular platters inside an airtight enclosure. Here are the key components:
- Platters – Made of non-magnetic material like glass or aluminum. Coated with a thin magnetic layer.
- Spindle – The central axis that spins the platters at 5000 to 15000 RPM.
- Read/Write Heads – One head for each platter surface. Floats just above the platter on a thin cushion of air.
- Actuator – Precisely moves the heads across the platters.
- Firmware – Embedded software that controls the HDD and interfaces with the OS.
Data is recorded by orienting magnetized particles on the platter surface. The read head detects the magnetic polarities to read back the data later. HDDs use parallel access across multiple platters to achieve fast data transfers.
Mechanical Limitations
The mechanical nature of HDDs causes certain limitations compared to SSDs. Seek time for moving heads and spin up time hurt latency. Fragmentation across the platters reduces sequential read/write performance over time. Moving parts also increase the failure rate and noise/vibration.
Choosing an Internal Drive
Choosing between an internal HDD and SSD depends on your performance, capacity and budget needs. Here are some guidelines for selecting one over the other:
When to Choose an Internal SSD
- You need very fast storage for intensive workloads like gaming or production.
- Maximum system responsiveness and fast boot times are critical.
- You frequently move your system which could damage a HDD.
- Silent operation is important in a library, bedroom etc.
- You don’t need huge amounts of storage and can afford the higher SSD cost per gigabyte.
When to Choose an Internal HDD
- You need lots of storage capacity for media files, games etc.
- Cost per gigabyte is very important.
- Fast access times are not critical for your usage.
- You have an external SSD for boot and priority programs, HDD for bulk storage.
Using Both SSD and HDD Together
A popular setup is to use both an SSD and HDD together to get the benefits of both. The operating system and applications are installed on the fast SSD. Large media files, documents and other data go on the HDD.
This dual drive configuration provides fast boot times, quick application launching and high responsiveness from the SSD. The HDD handles bulk storage of movies, photos, music and games cost effectively. An external USB SSD can supplement internal drives as well.
SSD Caching
Many motherboards support SSD caching to get HDD-like capacity with SSD-like performance. An SSD is set up as a cache for the main HDD. Frequently accessed data on the HDD is copied to the SSD cache automatically using machine learning algorithms.
Reads first check the SSD cache due to much lower latency. This avoids waiting for the HDD to spin up or move its head. Overall performance improves significantly even with a small SSD cache of 32GB – 128GB.
Hybrid Hard Drives
Another approach is hybrid hard drives or solid-state hybrid drives (SSHDs). These combine a small SSD onboard the HDD itself. The SSD portion acts as a fast cache for the HDD, speeding up access to frequently used data. Operating system files may also reside on the SSD side for faster boots.
However, since the SSD cache is relatively small at 8GB – 32GB, their overall performance gain is lower than discrete SSD and HDD setups. Large sequential transfers still rely solely on the HDD.
Internal SSD and HDD Interfaces
Internal storage drives use different interfaces to connect to the computer:
SSD Interfaces
- SATA – SATA revision 3.0 is the most common interface for 2.5″ SSDs. Provides up to 600MB/s bandwidth.
- PCIe/NVMe – Higher performance M.2 SSDs use PCI Express for up to 4000MB/s speed.
- U.2 – Enterprise SSDs in 3.5″ enclosures often use U.2 connectors on PCIe or NVMe interfaces.
HDD Interfaces
- SATA – 2.5″ and most 3.5″ HDDs use the SATA interface, providing up to 600MB/s speed.
- SAS – Used in enterprise server HDDs for improved performance and reliability vs SATA.
Choosing compatible SSDs and HDDs for your system’s motherboard interfaces is important. M.2 and U.2 drives require M.2 or U.2 slots. Ensure your motherboard has the required connector before purchasing the drive.
Operating System Support
Modern operating systems like Windows 10/11, Linux and macOS have full driver support for both SSDs and HDDs. The drives are identified as storage devices under hard disk drives in the system.
However, the OS needs to support certain features to take full advantage of SSD performance like TRIM, NCQ and NVMe drivers. Windows 7 and earlier had limited SSD optimization. But Windows 8, 10 and 11 are SSD-aware out of the box for maximum performance.
Internal Storage Best Practices
Here are some tips for using internal SSDs and HDDs optimally and maintaining good performance long term:
SSD Best Practices
- Keep at least 10-20% free space available for good write performance.
- Enable TRIM on supported operating systems.
- Use the native AHCI or NVMe driver, not IDE/ATA.
- Avoid excessive drive partitioning which hurts performance.
- Prefer M.2 SSDs over 2.5″ SATA for best speeds in modern PCs.
HDD Best Practices
- Defragment drives occasionally to optimize data layout.
- Limit fragmentation by leaving 10-20% free space.
- Avoid excessive file churn and fragmented downloads.
- Use the Native Command Queuing feature if available.
- Manage vibration using SSDs/shock absorbers in RAID setups.
Conclusion
Internal SSDs provide huge performance benefits from faster access, lower latency and better reliability compared to traditional HDDs. However, HDDs still dominate for high capacity bulk storage uses. Using both together provides speed and capacity efficiently.
For most desktop users, pairing a 250GB-1TB SATA/PCIe SSD for OS and apps with a 1-4TB SATA HDD for data is the ideal combination. Go for an all SSD configuration if speed matters more than storage capacity or vice versa. Match the drive interfaces to your system’s capabilities for fully realized performance.