DataON Labs: Testing QLC NVMe SSD Storage with Microsoft Azure Stack HCI

Comparing Intel® QLC SSD performance versus Intel MLC SSDs and hard disk drives (HDDs)

Intel® 3D NAND drives use multi-level cell (MLC) technology. MLC drives, such as Intel DC P4510 NVMe SSDs, are very popular due to its price point but are limited to 8TB of storage capacity. For workloads that require high capacity or high-density storage like backup and disaster recovery, you might need to use HDDs, and maybe add a JBOD to meet your storage requirements. However, with new quad-level cell (QLC) technology, SSDs like the Intel D5-P4326 SSDs can now support large capacity 15TB and 30TB NVMe drives.

But how do the new QLC SSDs compare with MLC SSDs from a performance perspective? And how do they compare against HDDs?

We did VM Fleet performance testing with a two-node Azure Stack HCI solution consisting of DataON S2D-5224 nodes with dual Intel® Xeon® Gold 6248 processors and 512GB RAM (per node).

We tested the following configurations:

  1. QLC SSD Config – 4x Intel® D5-P4326 NVMe 15TB QLC SSDs (storage) with 2x Intel P4610 NVMe 1.6TB SSDs (cache) per node
  2. MLC SSD Config – 4x Intel P4510 NVMe 4TB MLC SSDs (storage) per node (no cache)
  3. HDD Config – 4x 14TB HDDs (storage) with 2x Intel P4610 NVMe 1.6TB SSDs (cache) per node

Because Intel requires at least two 1.6TB NVMe cache SSDs (Intel DC P4510 SSDs or Intel DC P4610 SSDs) in front of QLC SSD storage, we’ve configured the HDD as hybrid storage with identical 1.6TB Intel DC P4610 SSD cache configurations.

[QLC Table 1]

Using VM Fleet, we tested the configurations with two-way mirror fault tolerance. We performed random 4K testing (block IOPS, throughput, and latency) and sequential 512K testing (block throughput, IOPS, and latency testing).

[QLC Table 2]

Random 4K Block IOPS Testing

[QLC Table 3]

The MLC SSD config performed best in the 100% Read, 100% Write, and 70% Read / 30% Write tests while the QLC SSD config performed slightly better in the 50% Read / 50% Write test.

When comparing the MLC SSD config versus the HDD config, the MLC SSD outperformed the HDDs in every test.

Random 4K Block Throughput Test

[QLC Table 4]

Overall, we see the same proportional results as Random 4K Block IOPS tests with only minor variances, with MLC SSDs outperforming QLC SSDs in most tests.

When comparing the MLC SSD config versus the HDD config, the MLC SSD outperformed the HDD in every test.

Random 4K Block Latency Test

[QLC Table 5]

Surprisingly, in the Random 4K Block Latency 100% Read test, the QLC SSD had the highest latency at 1.56ms.

The HDD had the lowest latency on the 100% Write test at 4.68ms, while the QLC SSD had the lowest latency for the 70% Read / 30% Write and 50% Read / 50% Write test.

Sequential 512K Block IOPS Test

[QLC Table 6]

The clear winner here was the MLC SSD on both 100% Read and 100% Write tests.

Sequential 512K Block Throughput Test

[QLC Table 7]

The storage solutions performed proportionately to the Sequential 512K Block IOPS tests.

Sequential 512K Block Latency Test

The MLC SSD config outperformed the other configs on both 100% Read and 100% Write tests.


QLC NVMe SSD storage is a good all-flash design option for Azure Stack HCI depending on your workloads and application usage. With QLC SSDs you can get more capacity and possibly eliminate the need to purchase an expansion JBOD for additional storage. This is especially important in backup solutions because write speeds are faster. In addition, the increased storage capacity makes it possible to create more VMs.

Although MLC NVMe SSD storage had the overall best performance in low queue and normal VM Fleet tests, it is limited in capacity compared to MLC SSDs and HDDs. QLC SSD storage performance was better than MLC SSDs and HDD, especially when write operations were involved.

When looking at the comparisons between choosing HDD or QLC SSD storage, QLC SSDs are superior in both overall IOPS, throughput and latency, and capacity.

QCL SSD pricing (cost-per-GB) falls in between an HDD and MLC SSDs. If you’re considering a high-density solution that requires higher performance for your workload then Intel QLC SSD storage can be an attractive option.