New DapuStor SSD pairs high-capacity QLC with a permanent pSLC region — trades 6% to 20% of its QLC capacity for more than 7x faster random writes

DapuStor unveiled a new J5060 enterprise SSD that combines SLC and QLC flash memory in a single drive. The drive's firmware temporarily activates a portion of the QLC cells as pseudo-SLC (pSLC) memory, sacrificing some capacity for faster performance. The configuration varies based on the specific model, trading between 4TB and 1.2TB of QLC capacity for speed gains ranging from 6% to 20%.

The fixed pSLC region is exposed as an individual block device to the host computer. Compared to traditional consumer QLC drives, which temporarily store fast data in a cache before transferring it to the QLC memory, DapuStor's approach keeps the pSLC region as a permanent fixture. This configuration improves the drive's random write performance by over seven times and reduces average 4K random write latency to below 8 microseconds.

The pSLC memory boasts more than 25 times the program/erase cycles of the QLC region, although exact durability numbers remain undisclosed. The J5060 comes in capacities ranging from 15.36TB to 122.88TB in a U.2 form factor for PCIe 4.0 x4. DapuStor achieves this dual-mode configuration through three firmware changes: die-level isolation, optimized SLC reserve allocation, and region-aware I/O scheduling.

The technology is not new, as the NVMe specification has supported this arrangement since 2019, but DapuStor's implementation uniquely provides each host with a separate block device. Competitors, such as Sandisk and Micron, offer alternative solutions that either eliminate the need for SLC buffering or utilize separate cache drives. However, these solutions still have performance differences and pricing considerations.