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Low-cost NVMe with a Few Caveats- Tech Advisor



Initially, it appeared that Crucial held back from the NVMe market. Its first M.2 form factor drives, the MX500, was a SATA part, and it only produced the NVMe P1 series two years ago.

The P1 isn’t at the performance level of some NVMe drives, but an entry-level design that offers a reasonable price per GB for those with an M.2 slot they are itching to occupy.

We now know that Micron (Crucial) has performance ambitions in the pipeline, but also sees the budget builders as an essential slice of the market. And, the new P2 series is designed to replace the P1 with a quicker module at an even keener price.

Does the P2 have the right credentials to entice the cash-strapped system builders, or is going to suffer from comparison with the unbranded high-performance competition?

Design & Build

As this drive is primarily designed to be cost-effective, there isn’t much to talk about in terms of the external design. This is a typical a single-sided M.2 2280 board where all the chips are hidden under the label.

The label reveals that the review module was manufactured in Mexico, and that warranty is void if you remove said label.

It comes in a minimalist cardboard box with a plastic tray to protect it, and a small leaflet directing you to a web location where you can find an installation guide, transfer software and support.

Like its predecessor, the P2 uses Micron 3D NAND modules, but the designers swapped out the Silicon Motion controller for one made by Phison. And to accompany that choice, the designers have redesigned how the cache works accordingly.

Crucial did not provide much more technical information about this design than that, and a conversation I’ll mention later reveals a possible reason why.

Specs & Features

From a performance perspective the Crucial P2 bucks the trend. What we are used to seeing in NVMe drive designs these days are increases in both read and write speeds in conjunction with the increased capacities of the drives.

The logic of this thinking is that bigger drives use more NAND modules, and they can be operated in parallel, increasing the overall throughput. And, larger drives often have proportionally more cache memory, further enhancing speeds.

Where the P2 surports this model is in reading performance, where the 500GB review drive is faster at reading by around 200MB/s over the 2,100MB/s that the 250GB model delivers.

But, and this is confusing, the larger drives are slower than the smaller capacity units at writing. Low write performance is a weakness, but the 500GB has a level of write speed that you’d associate with a drive that has saturated its cache and reveals the underlying NAND performance.

Digging further into the specifications of the P2, I discovered that it has no DRAM cache, and instead relies on some TLC modules being allocated as SLC to enhance transfer performance.

More head-scratching information is that the Total Bytes Written is 150TB for both 250GB and 500GB capacities.

Surely, when you’ve twice the amount of space, there should be double the TBW, or on the larger drives, the NAND stops working after only half the number of operations of the smaller unit?

I posed this exact question to Crucial, and this was the reply:

‘You may notice an endurance variance between your results and our published specs, as our specs are set to allow for potential product transitions in the future. The Crucial P2 SSD currently relies on Micron TLC 3D NAND technology, but over time may include a mix of Micron’s TLC and QLC NAND technologies. By mixing types of NAND with different capacities, we’re able to make product adjustments and decisions based on emerging and changing technology, preferred capacities, and flexibility to match movement of the overall market.’

So, to break that down; Crucial wants to use TLC (Triple-Level Cell) NAND to begin with, which has better endurance, and then move to cost-saving QLC (Quad-level Cell). And as not to confuse anyone its downgrading TBW expectations right now.

Therefore, depending on the direction that the wind is blowing in NAND production, you should always get 150TBW out of the 500GB P2, but you might get more than that.

Performance

I had low expectations for the P2, but it managed to surprise us repeated. I used CrystalDiskMark 7.0h and AS SSD 2.0. Starting with CrystalDiskMark, I soon started getting scores I wasn’t anticipating.

The read performance might not cause Samsung cause for concern, but 2,310 MB/s is more than four times the speed of the absolute best SATA SSD you can buy. But what shocked me was that the review drive managed 1,860MB/s writes, nearly double that predicted by Crucial, and substantially better than the P1.

Using CrystalDiskMark 7.0h Real-world mode revealed that read performance is much lower at 1621MB/s, but write performance was only a tiny bit less at 1,840MB/s.

AS SSD usually is much less optimistic about speed than CrystalDiskMark, and the numbers were less with reading speeds of 2,013MB/s and writes of 1,380MB/s. That’s below the quoted read performance, but above that predicted for writing.

As with overall throughput, IOPs are better than the quoted numbers, but they’re not anywhere near what I’d consider ideal. Less than 60K on 4K write is about of fifth of what the best NVMe units can achieve. Read IOPs are over 240K, but that’s hardly record-breaking.

The significant caveat to these numbers is that Crucial has already stated that it will move to QLC NAND, and therefore its quoted performance scores are the ones that are guaranteed. Mileage on retail parts, therefore, may vary.

Price

The P2 comes in only two capacities initially, 250GB and 500GB. A 1TB model is being added soon Crucial tells us, though not the 2TB option that the P1 has in its range.

The 250GB model costs only £47.99 (US$49.99), and its bigger brother is an even better deal at £63.59 (US$64.99) directly from Crucial. You can also buy them from Amazon, BT and eBuyer.

That’s less than some SATA M.2 drives cost, and it’s about 12% cheaper than the WD SN550 500GB, and only slightly more expensive than the P1 model that it supersedes.

Verdict

The P2 is a curious beast. The naming suggests that it replaces the P1, but at launch, this design doesn’t have all the capacities options yet to replace it entirely.

In a direct performance comparison, it is better, and at least in the review modules much better than the P1, it replaces. This product was never about speed, it was about making a cheap NVMe solution that satisfies the bottom end of this market, and Crucial succeeded in that objective.

The balancing factor is the price, but it assumes that the prospective buyer is only looking to launch the OS and apps quickly and not write video many files using the P2. The IOPs on this drive aren’t anything special, so writing lots of files, irrespective of size, won’t demonstrate this drives strengths.

I should also mention that no encryption is included, should you be keen on that level of security.

However, at this price, the P2 does have some potential. Especially for those with two M.2 slots that they could combine using two P2 sticks in RAID model to deliver 4GB/s reads and 2GB/s writes, or failure redundancy. When the 1TB capacity drive finally turns up, that could be the most affordable way to get 2TB of high-performance NVMe storage.

Used on its own, the P2 is an inexpensive option for anyone building a new system on a tight budget that wants better than SATA SSD performance for booting and enough capacity for applications.

The problem that Crucial has is that for only a little more, you can purchase a lesser-known brand drive with better performance. Or, as an alternative, the Kingston A2500 and Intel 600p are branded, don’t cost much more, and offers higher quoted write speeds.

Those looking for more speed will probably more interested in the upcoming Crucial P5 series than the P2, but for those with a tight budget, the P2 might be worth considering.

Specs
Crucial P2: Specs

Capacities: 250GB/500GB/1TB

Capacity tested: 500GB

Tested 4KB performance: 52.38/147.52MB/s

Tested sequential performance: 2,310/1,860MB/s

Quoted sequential performance:2,300/940MB/s

Controller: Phison PS5013

Encryption: N/A

Flash technology: 96-layer 3D-NAND 3bit TLC, or QLC

Connection: PCIe Gen3 x4, NVMe 1.3

Claimed power consumption: 3.5W active / 800mW idle

Warranty: 5 years

Form Factor: M.2 80mm Single-Sided

About the author: SubSellKaro

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