Enterprise NVMe SSD Buying Guide: Class, Endurance and UK Prices

Enterprise NVMe SSD: what the word enterprise means on a maker's sheet

NVMe names how a drive talks to its host. It does not tell you the drive's class. Samsung's PM9A3 white paper says data centres and enterprise storage have traditionally been two separate SSD markets, with enterprise drives tending to emphasise special features and robust reliability. Kioxia draws the line in hardware. Its April 2024 tech brief says its enterprise SSDs, such as the CM7 Series, include dual-port functionality, giving a second path to the same drive if a path fails, and that its data centre PCIe NVMe SSDs support single-port only.

Same generation and same capacity span: what separates these two lines on this sheet is the second port, the U.3 or U.2 connection and a step in speed. Do not stretch that into a rule for other makers. Micron's 9400 sheet lists a U.3/U.2 single port x4 and its 7450 sheet lists single-port M.2 and E1.S, though Micron also calls sector-size support an enterprise feature. If you need two paths to a drive, the word enterprise in a listing title will not settle it. Ask for the port count of the exact part.

What enterprise NVMe storage changes against SATA and SAS

Samsung claims its PM9A3 delivers more than ten times the read performance of SATA SSDs, with lower latency. That is a maker's claim for one drive, and we have not tested it. The SAS half of the question, covering ports, links and maker-quoted speeds, is set out on SAS vs NVMe and is not repeated here.

The change that rarely gets a headline is management. Kioxia's brief says the NVMe specification includes features for administrators to monitor SSD health. The log fields it lists include a critical warning when available spare capacity falls below threshold, another when the drive has gone into read-only mode, and a Percentage Used field, which it describes as a vendor-specific estimate of the drive's life. For a buyer of a used row, that last field is the reading worth asking the seller about.

PCIe generations: what moves between Gen3, Gen4 and Gen5

Samsung's white paper says PCIe Gen4 bandwidth is twice that of Gen3. The sheets we hold show a similar step from Gen4 to Gen5, read as makers' peak sequential figures for different drives:

• PCIe Gen4: Samsung PM9A3 U.2, up to 6,900 MB/s. Micron 9400, up to 7,000 MB/s. Kioxia CD8, up to 7,200 MB/s.
• PCIe Gen5: Kioxia CD8P, up to 12,000 MB/s. Kioxia CM7, up to 14,000 MB/s.

The top Gen5 figure is about twice the top Gen4 one on our arithmetic. These are not tests of ours. The same sheets also show how much capacity moves a figure: the U.2 PM9A3's sequential write runs from 1,500 MB/s to 4,100 MB/s across its four sizes, all on one generation.

Two limits sit outside the drive. The host sets one: Samsung's paper reports PM9A3 results on PCIe Gen3 servers and puts the modest read gain there down to the Gen3 interface limit, so your backplane's generation belongs in the decision, as enterprise SSD explains. Power sets the other: the KIOXIA, Meta and Microsoft white paper says 25 W is required to saturate a PCIe 4.0 x4 link. It also says EDSFF drives are designed for PCIe 5.0 and 6.0, though initial E1.S SSDs were PCIe 4.0.

Read-intensive or mixed-use: the enterprise NVMe endurance split

Most families here come in two grades. Kioxia calls its CM7-R read-intensive at 1 DWPD and its CM7-V mixed-use at 3 DWPD. Micron labels the 7450 PRO read-intensive at one drive write per day and the 7450 MAX mixed-use at three. Table 3 of its specification tops out at 14,000 TB written on the 7,680 GB PRO and 35,000 TB on the 6,400 GB MAX for 4K random writes, or 48,800 TB and 61,800 TB for 128K sequential. Kioxia defines one drive write per day as writing the drive to full capacity once a day for the specified lifetime. The trade for extra endurance is capacity:

The 6,400 GB Micron 9400 carries 2.5 times the TBW of the 7,680 GB one (our arithmetic). On Kioxia's definition, a 7,680 GB drive at 1 DWPD takes 7,680 GB of writes a day and a 6,400 GB drive at 3 DWPD takes 19,200 GB, again our arithmetic. Sequential reads do not separate the Micron 7450 grades; random writes do.

That gives a useful tell on these families: sizes such as 1.6, 3.2 and 6.4 TB sit on the higher-endurance side, and 1.92, 3.84 and 7.68 TB on the read-intensive side. It holds on the sheets above and not necessarily elsewhere, so confirm it from the part number. Micron also notes that not all MAX configurations are available in all markets, so a size on its sheet may not be one you can buy here.

Power loss protection and QoS: two lines to read carefully

Power loss protection answers a specific failure. Samsung explains that on an unexpected power loss, cached data in a drive's internal DRAM buffers can be lost. The KIOXIA, Meta and Microsoft white paper describes PLP as using the backup power of a solid capacitor to record buffered data to NAND flash. Samsung states enterprise PLP for the PM9A3, Micron states full power-loss protection for the 7450 and Kioxia lists PLP on the CM7-R. Each line speaks for that family, so check the part you are buying.

QoS is about the slowest responses rather than the middle of the pack. Micron's 7450 sheet gives a typical read latency of 80 microseconds and defines typical as the median. Its brief then quotes 2 ms and below at 99.9999%, up to queue depth 32, on a 4KB, 100% random, 70% read workload. Samsung's white paper reports its PM9A3 at 99.99 percent on Samsung's own test, and its brief says the firmware prioritises QoS for sustained random workloads.

Those are different percentiles on different workloads, so they cannot be set against each other, and we print no winner. When you compare two drives on QoS, make sure the percentile, the queue depth and the read and write mix match first.

Enterprise NVMe M.2 and 2280: a slot drive, not a bay drive

Enterprise M.2 does exist. Micron lists the 7450 PRO in M.2 2280 at 480GB and 960GB and in M.2 22110 at 960GB, 1920GB and 3840GB, states full power-loss protection for the series, and describes the 22x80 mm version as designed for server boot use. Samsung's white paper gives the PM9A3 M.2 up to 3.84TB. One source conflict to note: one table in Micron's brief prints 22 x 100 mm; the same brief elsewhere and the specification print 110 mm.

The limits are physical. Samsung's form-factor table gives M.2 a maximum of 8.25 W against 25 W for U.2, and marks M.2 as neither hot-swap nor dual-port. The KIOXIA, Meta and Microsoft white paper says replacing an M.2 SSD normally means powering the whole server down, that M.2 has no presence-detect capability, and that M.2 SSDs cannot reach full PCIe 4.0 bandwidth in an 8.25 W envelope. Micron's brief bears that out within one family: 5,000 MB/s sequential read on the 7450 in M.2 against 6,800 MB/s in E1.S.

Makers do not all read alike here. Micron's 7450 sheet lists surprise insertion and removal and hot-plug capability for a series that includes M.2, which sits awkwardly with Samsung's table, so treat them as two makers' statements and check the sheet for the part. At the 2022 Flash Memory Summit a Microsoft speaker said M.2 may linger for boot devices but will fade away for performant data storage. That is a presenter's view, not a specification.

At the time shown, the enterprise M.2 NVMe table holds no listings in stock. We count these and print no separate table for them. Any such row also appears in the main table further down this page.

Enterprise NVMe 1TB, 2TB and 4TB: what the sheets actually list

Treat these as nominal sizes. On Samsung's PM9A3 U.2 and Micron's 7450 PRO in M.2 22110, a 1TB search means 960GB, a 2TB search 1.92TB and a 4TB search 3.84TB. Kioxia's CM7-R starts at 1,920 GB, and Micron's 9400 starts at 6,400 GB, so that family offers nothing near 1, 2 or 4 TB at all.

Samsung's own documents disagree at the top end. Its PM9A3 data sheet lists U.2 up to 7.68TB, while its white paper says capacities reach 15.36TB for U.2 and its brief also lists 15.36 TB. We print the conflict rather than pick a figure, so take any 15.36 TB PM9A3 listing back to the part number.

Enterprise NVMe drives on Amazon.co.uk: live prices

The table holds 23 listings right now. Lowest per TB: £187.00/TB. Prices are pounds sterling inc VAT, as Amazon.co.uk lists them at the time shown at the top of the page. The table takes listings recorded as NVMe in our enterprise SSD family and leaves out Micron 2400 M.2 and 2450 Series listings, which we do not class as enterprise drives. A row with no recorded interface cannot appear.

We do not split this table by form factor, so read each title: 2.5-inch, U.2, U.3 and EDSFF rows can sit side by side, and they do not go in the same bays. The pages for each shape go further on fit: U.2 SSDs, U.3 SSDs and E1.S SSDs.

How to choose an enterprise NVMe SSD

• Shape first. The bay or slot in your server decides between U.2, U.3, E1.S and M.2, and the rest of this list only matters afterwards.
• PCIe generation. Match it to your host, because the host's link can cap the drive, as Samsung's Gen3 results show.
• Grade. Multiply capacity by DWPD to get daily writes, then compare that with your own workload before paying for a 3 DWPD line.
• Ports. If you need two paths to one drive, confirm dual-port on the exact part. Neither the word NVMe nor the word enterprise promises it.
• Power loss protection. Confirm it on the maker's sheet for the family.
• QoS. Only compare figures taken at the same percentile, queue depth and read and write mix.
• Condition. Read that column and the seller's wording on Amazon.co.uk, then press Buy on Amazon only once the part number matches the sheet you read.