QLC vs. TLC

What is QLC vs. TLC?

Enterprises choosing between QLC (Quad-Level Cell) and TLC (Triple-Level Cell) SSDs must consider that each has strengths that make it suitable for specific applications.

There are several major factors that must be considered:

Workload type

• QLC SSDs are better suited for read-heavy applications where data is accessed frequently but not written or modified as often and latency isn’t a top concern. For these scenarios, the slower write speed and lower endurance of QLC SSDs are acceptable trade-offs for the high storage capacity and lower cost.

Use cases include:

- Mainstream and mixed primary workloads such as non–latency-sensitive database applications, where striking the balance between cost and performance a chief consideration.

- A secondary storage target optimized for high-performance backup, disaster recovery, or tiering, with the performance to run other applications such as development/testing and analytics.
 

• TLC SSDs are better suited for write-intensive or mixed workloads, which require higher endurance, lower latency, and faster write speeds. TLC SSDs are a good fit for more demanding workloads.

Use cases include:

- Databases: Where data is frequently written, modified, and read, such as transactional systems.

- Virtualization: For virtual machines that require fast, reliable access to data, and frequent read/write operations.

- High-Performance Computing (HPC): For workloads like data analysis, AI, and real-time applications where performance and endurance are critical.

- Cloud Storage: For applications where both read and write performance are essential, such as SaaS platforms or enterprise data processing.
 

Performance requirements

• QLC SSDs are ideal for situations where capacity and cost are more important than performance. While QLC SSDs provide slower write speeds, they still outperform traditional HDDs in read performance, which makes them viable for large-scale, lower-performance storage needs.

- Enterprises that need large storage capacity but have more relaxed performance requirements can benefit from QLC drives in applications like video streaming, data archiving, or backup solutions.
 

• TLC SSDs are the best choice for an enterprise requiring higher IOPS (input/output operations per second), faster sequential reads/writes, or better endurance. They are well-suited for:

- Mission-critical applications where fast read/write operations directly impact business functions.

- Low-latency environments that demand high-speed performance for rapid data access and processing.
 

Endurance and reliability

• QLC SSDs have lower endurance than TLC due to the higher number of bits stored per cell, meaning they can handle fewer write cycles before wearing out. This makes them less suitable for high-write environments but acceptable for archival or cold storage where write operations are infrequent.

- Enterprises needing cost-effective storage with moderate endurance can leverage QLC SSDs for infrequently written data.
 

• TLC SSDs offer greater endurance and can handle more write cycles than QLC SSDs. This makes them ideal for environments where data is frequently written, updated, or deleted.
  

- For enterprises handling mission-critical workloads or applications requiring frequent writes, TLC SSDs provide the durability and reliability needed to avoid premature drive failure.
 

Cost considerations

• QLC SSDs are typically cheaper than TLC drives due to their higher storage density, making them a good choice for enterprises that need large storage volumes without stretching their budgets. For cold data storage, where performance is less important but capacity is essential, QLC SSDs provide an economical solution.
  
  
• TLC SSDs are typically more expensive than QLC drives, they still offer a good balance of performance, endurance, and cost. Enterprises that need higher performance and endurance but still need to manage costs can find TLC SSDs an affordable option for more demanding applications.
   

Use cases

• QLC SSDs are ideal for:

- Mainstream and mixed primary workloads such as non–latency-sensitive VMware, (SAP, Oracle, and Microsoft SQL Server) database applications, providing cost and price performance balance.

- Cold storage: Archiving data that is rarely accessed.

- Backups and disaster recovery: High-performance backup, disaster recovery, and tiering, plus the performance to run other applications such as development/testing and analytics.

- Data lakes: Large data repositories where data is frequently read but not often written or modified.

- Content delivery: Streaming services or media storage where large amounts of data are served primarily in a read capacity.
 

• TLC SSDs are ideal for:

- Database applications: Accelerated read/write performance for running latency sensitive workloads where accelerated performance is critical such as large OLTP (Online Transaction Processing) databases.

- Virtualized environments: Running virtual machines and containers with frequent data reads and writes.

- Cloud computing: Applications that require a mix of read and write performance, such as web apps and data services.

- Enterprise workstations: Workloads that involve frequent data processing, such as video editing, 3D rendering, or software development.
 

Future scalability and upgrades

• QLC SSDs for scale-out storage

- QLC is more attractive for enterprises planning to scale their storage infrastructure rapidly, as the cost per GB is lower. It is especially useful for enterprises with big data needs or those handling massive datasets over time.
 

• TLC SSDs for flexible growth

- TLC SSDs allow for both performance and scalability, making them a better long-term investment if enterprises plan to increase the intensity of their workloads or anticipate more demanding storage requirements in the future.
 

Conclusion

• Choose QLC SSDs if the priority is high storage capacity at a low cost, especially for read-heavy workloads, archival storage, or less critical applications where write speed and endurance are not key concerns.
   

• Choose TLC SSDs for mixed or write-heavy workloads that require greater durability and faster access to data, such as databases, virtual environments, and performance-critical applications.