Crucial's First NVMe SSD: P1 M.2 With QLC NAND

Micron's consumer-oriented Crucial brand is finally entering the world of NVMe SSDs with the new Crucial P1 M.2 SSD. The P1 is an entry-level NVMe drive using four bit per cell (QLC) NAND flash memory and the Silicon Motion SM2263 controller. This is the same basic formula as used in the Intel 660p, the only other consumer QLC drive on the market so far. Micron has brought their own firmware customizations, so while the performance characteristics are similar to the Intel 660p they are definitely not the same drive. The Crucial P1 has slightly lower usable capacities than the Intel 660p, which translates into slightly more spare area available for garbage collection and SLC caching. Unlike the Intel 660p, the Crucial P1 uses the same 1GB DRAM per 1TB NAND ratio as most MLC and TLC SSDs.

With top sequential speeds of only 2GB/s, the Crucial P1 doesn't really need all four PCIe lanes, but Silicon Motion's entry-level SM2263 controller still has four instead of the two that some other low-end NVMe controllers use. Given the use of QLC NAND, the P1's SLC cache is far more important than it is on drives with TLC NAND. Micron has taken a similar approach to what Intel did with the 660p by making the SLC cache not just a write buffer but a full-time dynamically sized read and write cache. All data written to the Crucial P1 hits the SLC cache first, and is compacted into QLC blocks only when the drive's free space starts running low. This means that a mostly-empty drive will be using tens or hundreds of GB of SLC, but as it fills up the cache will shrink down to just 5-24GB depending on the model. All of Crucial's official performance specifications are for the SLC cache.

As with the Crucial MX series of SATA SSDs, the Crucial P1 features a greater degree of power loss protection than typical consumer SSDs, though not the fully capacitor-backed protection that most enterprise SSDs feature. With the MX500, Crucial had already substantially reduced the number of capacitors required for their partial power loss protection thanks in part to a reduction in write power requirements for their 64-layer 3D NAND. The P1 gains additional data security from its SLC-first write policy, which eliminates the partially-programmed page risk. However, there is still a tiny bit of used data buffered in volatile RAM, on the order of a few MB at the most.

The rated write endurance of 0.1 drive writes per day is low even for an entry-level consumer SSD, but given the large drive capacities it is adequate. The P1 is definitely not intended to be the workhorse of an enthusiast system with a write-heavy workload, but for more typical read-oriented workloads it offers better performance than SATA SSDs.

The initial MSRPs for the Crucial P1 are unimpressive: it's substantially more expensive than the Intel 660p, and about matches some of the most affordable high-end NVMe drives like the HP EX920 and ADATA SX8200. If Micron can catch up to Intel's pricing and compete for the lowest $/GB among all NVMe SSDs then the Crucial P1 has a shot at success.

The 2TB model will be launching slightly later due to using DDR4 DRAM instead of the DDR3 used by the 500GB and 1TB models. We are testing the 1TB Crucial P1, with some results already in our Bench database. Look for our full review next week.