SSDs (solid-state drives) and HDDs (hard disk drives) are two different types of computer storage devices. SSDs use flash memory chips to store data, while HDDs store data on quickly rotating platters or disks with magnetic surfaces. This key difference leads to significant performance advantages for SSDs compared to HDDs.
Overall, SSDs have much faster read and write speeds than HDDs. Typical SATA SSDs can read and write data at 200-550 MB/s, while SATA HDDs max out at around 160 MB/s. This makes SSDs better suited for tasks that require rapidly accessing or processing large amounts of data. However, HDDs tend to have higher capacities available for the same price as SSDs. We’ll dig deeper into the speed differences and other factors in the sections below.
SSD Basics
SSDs, or solid-state drives, are a type of storage device that uses flash memory to store data, unlike traditional hard disk drives (HDDs) that use spinning platters. SSDs have no moving parts since they use integrated circuits rather than mechanical components to store and retrieve data.
Flash memory in SSDs store data in arrays of floating-gate transistors called NAND flash memory cells. These cells trap electrons in an isolated gate to represent binary 1s and 0s for data storage. The cells are addressed using row and column circuits to read and write data very quickly with low latency and access times, which gives SSDs much faster data transfer speeds compared to HDDs. SSD controllers connect the flash memory to the computer and manage all data writing and reading operations.
Since SSDs have no moving parts, they provide very consistent and reliable performance compared to HDDs which can suffer from mechanical failures over time. SSDs are also more resistant to physical shock, operate silently with lower power consumption, and have faster boot and loading times for computers and games.
Sources:
https://www.extremetech.com/gaming/210492-extremetech-explains-how-do-ssds-work
https://www.avast.com/c-what-is-ssd
HDD Basics
Hard disk drives (HDDs) store data magnetically on quickly rotating platters. Inside the HDD case is a spindle that rotates the platters at speeds up to 10,000 RPM. How do hard drives work. The platters are coated with magnetic material and the data is stored in binary code across the disks in concentric tracks.
An actuator arm holds the read-write heads in position over the disks as they spin. As the platters rotate, the heads hover just above the surface to read and write data. The heads move in and out across the platters to access different tracks. HDDs rely on moving parts for mechanical operation, which makes them susceptible to damage from shock or vibration. Overall, the magnetic spinning disks and moving read/write heads are the core components that enable HDDs to store and retrieve data. How do Hard Drives Work – Everything you need to know.
Speed Factors
There are several key factors that contribute to the speed differences between SSDs and HDDs:
Rotational Speed – HDDs consist of spinning magnetic disks called platters. The speed at which these platters spin is referred to as rotational speed, measured in revolutions per minute (RPM). Common speeds are 5400 RPM and 7200 RPM. Faster RPMs allow data to be accessed more quickly. SSDs have no moving parts, so rotational speed does not apply.
Seek Time – Seek time refers to the delay for the HDD’s read/write head to move and locate data on the drive’s platter. Seek time is typically 1-12 milliseconds for HDDs. SSDs have near instantaneous seek time due to using flash memory and having no moving parts.
Data Transfer Rate – Also known as interface speed, this is the rate at which data can be transferred to and from the storage device. HDDs are limited by disk speed, so maximum data transfer rates peak around 160-210 MB/s for SATA interfaces. SSDs can achieve 550+ MB/s transfer rates over SATA due to flash memory.
Real-World Performance
When it comes to real-world use cases, SSDs consistently outperform HDDs in several key areas:
Boot Times: SSDs can boot computers significantly faster than HDDs. With an SSD, a computer can go from fully powered off to ready to use in under 10 seconds. HDD boot times are typically 30 seconds or longer (https://www.youtube.com/watch?v=07PhE2nlpPw).
Game Loading: SSDs can dramatically decrease load times in games. Large open world games like Skyrim or GTA V can load new areas 2-4x faster on an SSD compared to a HDD (https://www.youtube.com/watch?v=07PhE2nlpPw).
File Transfers: Because of their higher sequential read/write speeds, SSDs can transfer multi-gigabyte files noticeably faster than HDDs. The difference is especially noticeable for large batches of smaller files.
So for typical daily tasks like booting the computer, loading games, launching apps, and file operations, users can expect a more responsive experience with SSD storage.
Synthetic Benchmarks
Synthetic benchmarks like CrystalDiskMark and AS SSD provide a consistent way to compare the performance between SSDs and HDDs. They perform sequential and random read/write operations and report results in MB/s. However, these tools don’t necessarily reflect real-world usage.
In CrystalDiskMark, a SATA SSD can achieve sequential read speeds of around 500 MB/s compared to 150 MB/s on a SATA HDD. For random reads, an SSD gets over 90 MB/s while a HDD struggles to reach 1 MB/s. The AS SSD benchmark shows similar results, with SSDs easily outperforming HDDs in all areas (Source 1).
While these synthetic tests demonstrate the immense speed advantage SSDs have over HDDs, especially for random operations, real-world usage tends to be a mix of sequential and random I/O. So synthetic scores only tell part of the story.
Impact of Capacity
There is a perception that SSDs slow down as capacity increases, while HDDs maintain speed regardless of capacity. In reality, capacity does impact speed for both SSDs and HDDs, but in different ways.
For SSDs, higher capacity drives often have better performance due to having more NAND flash channels and controllers. However, very high capacity SSDs may have slightly lower speeds due to needing more sophisticated controllers to manage the NAND. Overall, most SSDs maintain excellent speeds even at high capacities.
For HDDs, higher capacity drives have more platters and heads, allowing higher internal transfer speeds. However, the increased weight of larger HDDs can reduce spindle speeds slightly. Very high capacity HDDs may also see a minor reduction in access times due to needing to move heads further to reach data. But again, the impact is quite small in most cases.
Overall, both SSD and HDD speeds are generally consistent regardless of drive size for most real world usage. But SSDs have a clear edge in read/write speeds at all capacities. According to AVG, even a budget SATA SSD is over 3x faster than an HDD for sequential reads and writes.
Lifespan Considerations
When comparing SSDs and HDDs, lifespan is an important factor to consider. SSDs have a limited number of write cycles before their NAND flash memory cells start to wear out and eventually fail. HDDs on the other hand have moving mechanical parts like actuator arms and platters that are prone to failure over time.
According to research, today’s SATA SSDs last as long or even longer than hard drives when used normally. SSDs are rated for a certain number of drive writes per day (DWPD) over a 5 year period. For consumer SSDs this is around 0.3 – 1 DWPD, whereas enterprise SSDs can handle up to 10 DWPD. In real-world usage for a typical user, an SSD is estimated to last between 6-10 years before wear-leveling would impact performance.[1]
For HDDs, annualized failure rates are typically around 2-3% depending on the specific model and workload. HDD failures are often unpredictable and can increase over time as components wear out. HDD lifespans tend to be 3-5 years on average in active use before the probability of mechanical failure becomes a concern. Higher-end enterprise HDDs are rated for 24/7 operation for 5 years.[2]
In summary, today’s SSDs have closed the lifespan gap with HDDs for most standard workloads. However, heavy write-intensive uses like video editing may still favor HDDs for longer endurance over the SSD’s usable life.
[1] https://www.easeus.com/storage-media-recovery/ssd-vs-hdd-lifespan.html
[2] https://4ddig.tenorshare.com/hard-drive/ssd-vs-hdd-lifespan.html
Price Differences
When it comes to cost per gigabyte (GB), solid state drives (SSDs) tend to be more expensive than hard disk drives (HDDs). A 1 terabyte (TB) SSD may cost around $100, while a 1 TB HDD costs around $40 (SSD vs. HDD: Which is Better for You? – Ankmax Official Shop). However, SSD prices have been steadily dropping over time while HDD prices have remained relatively flat. Looking at cost per GB, HDDs are generally 3-4 times cheaper than SDDs. But SSD prices are slowly approaching HDD prices and the gap is narrowing.
It’s important to note that lower-capacity SSDs (128GB to 512GB) are significantly more expensive per GB than higher-capacity models. The largest SSDs (2TB+) tend to have the lowest cost per GB. HDDs maintain a steadier price across different capacities. Overall SSDs remain more expensive than HDDs in terms of dollar-per-gigabyte but offer substantial performance advantages that can justify the premium for many users.
Conclusion
In summary, SSDs and HDDs both have their merits and drawbacks. SSDs provide faster read and write speeds thanks to flash storage, lower latency, better shock resistance, silent operation, and lower power consumption. However, they come at a higher cost per gigabyte and have a limited number of write cycles. HDDs are much cheaper per gigabyte, have higher maximum capacities, and can write data indefinitely. But they are slower, noisier, consume more power, and are more prone to failure from shock damage.
When it comes to real-world performance, SSDs load applications and boot operating systems faster, have quicker file transfer speeds, and offer snappier everyday usage. Benchmarks consistently demonstrate SSDs outperforming HDDs across a variety of workloads. For most consumer use cases, the speed advantage of SSDs outweighs the lower cost per gigabyte of HDDs.
In the end, SSDs are the clear winner when performance is the priority. HDDs still play a role for high capacity cold storage at the lowest cost. But for primary drives and any usage requiring responsiveness, SSDs are the superior choice.