Question:

As a former employee of an SSD manufacturer, I am curious about the current state and future prospects of SSDs in data center applications. What are the main factors that limit the adoption of SSDs over HDDs in data centers, despite the superior performance of SSDs? How do HDD manufacturers compete with SSDs in terms of innovation and cost reduction? Do you foresee a scenario where SSDs will dominate or replace HDDs in data centers in the next decade?

Answer:

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> Solid state drives (SSDs) and hard disk drives (HDDs) are two types of data storage devices that have different advantages and disadvantages. SSDs store data electronically, while HDDs use mechanical components to store data magnetically. SSDs are faster, quieter, more reliable, and more energy-efficient than HDDs, but they are also more expensive and have lower capacities. HDDs are cheaper, have higher capacities, and are more suitable for long-term storage, but they are slower, noisier, less reliable, and more power-hungry than SSDs. >
> In this article, we will explore the current state and future prospects of SSDs and HDDs in data center applications, based on the following questions: >
> – What are the main factors that limit the adoption of SSDs over HDDs in data centers, despite the superior performance of SSDs? > – How do HDD manufacturers compete with SSDs in terms of innovation and cost reduction? > – Do you foresee a scenario where SSDs will dominate or replace HDDs in data centers in the next decade? >
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Factors Limiting SSD Adoption in Data Centers

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> According to a report by IDC, SSDs accounted for 31.7% of the total data center storage capacity shipped in 2020, while HDDs accounted for 68.3%. This shows that HDDs still have a significant share of the data center storage market, despite the rapid growth of SSDs in recent years. Some of the main factors that limit the adoption of SSDs over HDDs in data centers are: >
> – Cost: SSDs are still much more expensive than HDDs per unit of storage. For example, as of April 2021, the average price of a 1TB SSD was around $100, while the average price of a 1TB HDD was around $40. This means that SSDs are about 2.5 times more expensive than HDDs per terabyte. For data centers that need to store large amounts of data, such as cloud service providers, social media platforms, or video streaming services, the cost difference can be significant and prohibitive. > – Capacity: SSDs have lower capacities than HDDs, especially for the 3.5-inch form factor that is commonly used in data center servers. The highest capacity SSD available in the market as of April 2021 was 30.72TB, while the highest capacity HDD available was 60TB. This means that HDDs can store twice as much data as SSDs in the same physical space. For data centers that need to optimize their storage density, such as colocation facilities, edge computing sites, or hyperscale data centers, the capacity advantage of HDDs can be crucial. > – Compatibility: SSDs have different interfaces and protocols than HDDs, such as SATA, SAS, PCIe, NVMe, etc. This means that SSDs may not be compatible with some existing data center hardware and software systems that are designed for HDDs. For data centers that need to maintain their legacy infrastructure, such as enterprise data centers, government agencies, or financial institutions, the compatibility issue of SSDs can be challenging. >
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HDD Innovation and Competition with SSDs

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> HDD manufacturers are not standing still in the face of SSD competition. They are constantly innovating and improving their products to keep up with the increasing demand for data storage in data centers. Some of the recent innovations and trends in HDD technology are: >
> – Helium-filled HDDs: Helium-filled HDDs use helium gas instead of air inside the drive enclosure. Helium has lower density and viscosity than air, which reduces the drag and turbulence on the spinning platters and the read/write heads. This allows for more platters, higher speeds, lower power consumption, and lower noise and vibration levels. Helium-filled HDDs can achieve capacities of up to 20TB, while consuming 23% less power and generating 50% less noise than air-filled HDDs. > – Shingled magnetic recording (SMR) HDDs: SMR HDDs use a technique that writes data in overlapping tracks on the platters, like shingles on a roof. This increases the areal density and the storage capacity of the HDDs, but also reduces the write performance and the random access speed. SMR HDDs are suitable for data that is written once and read many times, such as archival, backup, or cold storage. SMR HDDs can achieve capacities of up to 20TB, while costing 20% less than conventional HDDs. > – Heat-assisted magnetic recording (HAMR) HDDs: HAMR HDDs use a laser to heat up a small area of the platter before writing data on it. This allows for smaller and more stable magnetic grains, which increases the areal density and the storage capacity of the HDDs, but also requires more sophisticated and expensive components. HAMR HDDs are suitable for data that requires high performance and reliability, such as hot or warm storage. HAMR HDDs can achieve capacities of up to 60TB, while delivering 30% higher performance than conventional HDDs. >
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Future Scenarios of SSDs and HDDs in Data Centers

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> The future of data storage in data centers is likely to be a hybrid of SSDs and HDDs, rather than a complete replacement of one by the other. SSDs and HDDs have different strengths and weaknesses, and different use cases and workloads. Depending on the data center’s needs and objectives, the optimal mix of SSDs and HDDs may vary. Some possible scenarios of SSDs and HDDs in data centers in the next decade are: >
> – SSDs for performance, HDDs for capacity: This scenario is based on the assumption that SSDs will continue to improve their performance, reliability, and endurance, while HDDs will continue to improve their capacity, density, and cost. In this scenario, SSDs will be used for data that requires high speed, low latency, and frequent access, such as databases, analytics, or caching. HDDs will be used for data that requires high capacity, low cost, and infrequent access, such as backup, archive, or cold storage. > – SSDs for hot and warm storage, HDDs for cold storage: This scenario is based on the assumption that SSDs will become more affordable and available, while HDDs will become more specialized and niche. In this scenario, SSDs will be used for data that is active, dynamic, or valuable, such as hot or warm storage. HDDs will be used for data that is passive, static, or less valuable, such as cold storage. > – SSDs for edge and cloud, HDDs for core and on-premise: This scenario is based on the assumption that SSDs will become more ubiquitous and distributed, while HDDs will become more centralized and consolidated. In this scenario, SSDs will be used for data that is generated or consumed at the edge or in the cloud, such as IoT, mobile, or web applications. HDDs will be used for data that is stored or processed at the core or on-premise, such as enterprise, government, or financial applications. >
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Conclusion

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> SSDs and HDDs are both important and evolving technologies for data storage in data centers. SSDs offer superior performance, reliability, and efficiency, but they are also more expensive and have lower capacities. HDDs offer lower cost, higher capacity, and more compatibility, but they are also slower, less reliable, and more power-hungry. The future of data storage in data centers will likely depend on the balance and integration of SSDs and HDDs, rather than the dominance or replacement of one by the other. Data center operators and managers should carefully evaluate their data storage needs and objectives, and choose the best combination of SSDs and HDDs for their specific use cases and workloads.