The Crucial P1 1TB SSD Review: The Other Consumer QLC SSD

Conclusion

The Crucial P1 SSD doesn't leave us particularly excited about the near-term prospects for QLC NAND in the consumer SSD market. The P1 is a decent entry-level NVMe SSD for less intensive workloads, but the wide gap between its best and its worst performance means the P1 comes with more caveats than most of its competition.

The Crucial P1 relies very heavily on its SLC cache to provide high performance, and that cache shrinks as the drive fills up. When the drive is full, a very write-heavy workload can overflow the cache and severely impact write speeds and even read performance to some extent. However when the drive isn't close to full, it is nearly impossible to fill the SLC cache with a realistic workload, and the Crucial P1 performs at least as well as any other entry-level NVMe drive, and sometimes rivals high-end NVMe drives. Compared to the Intel 660p, the SLC cache on the Crucial P1 seems to be more write-oriented and is not as good at accelerating read operations. It seems like the P1 may be a bit quicker to evict data from the cache and compact it into QLC blocks.

Overall the Crucial P1 is primarily aimed at consumer machines, and that definitely seems like the segment it's best suited for. A typical consumer use case would involve most of the large data on the drive coming from things like movies and video games that are rarely modified, as opposed to workstation workloads that generate massive files that constantly change. This is helpful to the P1 because it reduces the actual amount of writing the drive needs to do, though it does mean that the drive's variable-size SLC cache could end up quite small. On balance, even that small cache should be adequate given the limited amount of data that does change with most consumer workloads; though to be sure, overflowing the SLC cache is something that would be far more noticeable on the P1 than most TLC-based SSDs. But it is still not something that will happen to most consumers often enough to worry about.

That leaves the Crucial P1 as usually being very fast, and definitely faster overall than any SATA SSD. The use of QLC NAND doesn't cripple the drive, and is a detail that most consumers don't have to care about. Even at its worst, the P1 is still faster and more efficient than a mechanical hard drive. NVMe SSDs should aspire to more than that, but this will probably be true even of QLC SATA drives as long as they also avoid the low capacity points where high performance is impossible.

The downsides of QLC NAND are pretty easy to accept if they come with a significant price cut, but that is not yet the case for the Crucial P1 or the Intel SSD 660p. The Crucial P1 is 22 cents per GB and the Intel 660p is 19 cents per GB, so Micron obviously needs to drop their prices at least a little bit to be at all competitive. Meanwhile, mainstream SATA SSDs are about 16–17 cents per GB for 512GB and larger capacities, and there are some high-performance TLC-based NVMe SSDs in the 20-22 cents per GB range.

Ultimately if you are going to pay extra for a NVMe SSD instead of a SATA drive, at current prices there are far more compelling options than the Crucial P1 and Intel 660p. We're accustomed to seeing entry-level NVMe SSDs get undercut by more popular high-performance drives as prices in general trend downward, and the two QLC drives we have so far on the consumer market are continuing that pattern. When QLC comes to the SATA SSD market, prices will need to be at or below 13 cents per GB to avoid repeating this problem.