Review: Samsung 850 Pro 512GB

Introduction and design

The 850 Pro is Samsung's new flagship consumer SSD, and the follow-up to the wildly popular 840 Pro, which was one of the best performing SSDs money could buy when it launched in September 2012. We're reviewing the 512GB model here which is priced at £232 (US$399, around AUD$420).

Apart from a small change from an orange logo to red, the 850 Pro's product packaging and the metallic shell of the drive look just like the older model. It has identical dimensions, including a height of 6.8mm, which ensures it will fit into the smallest of laptops, and a similar diamond-cut chamfered edge.

Likewise, the drive is still based on 2-bit MLC NAND flash memory. But under the hood, Samsung has introduced a few performance-boosting enhancements. The MEX controller has received a 100MHz speed bump, to 400MHz, but the headline new feature is 3D V-NAND flash memory, Samsung's proprietary 3D technology, where the memory chips are layered vertically, as well as horizontally.

As flash memory cells get smaller, SSD makers are encountering the same problems the semiconductor industry is facing. The cells are now tiny, down to the size of 1nm, and at this scale the laws of physics mean charge easily leaks between them, requiring new materials and insulation techniques to allow for continued improvements in performance and capacity. A 3D arrangement mitigates some of these problems.

It's probable the entire industry will eventually adopt 3D flash, but Samsung has beaten its competitors to market with a working product.

Samsung has its fingers in an exhaustive list of pies in the world of consumer electronics, selling retail-branded products that we're all familiar with, such as Galaxy phones and tablets, as well as many of the components other firms use in their own designs, including displays and flash memory chips. Samsung is the largest NAND producer in the world, with its own fabrication plant in Korea, which gives it a strong leg-up in the SSD business.

Not only does it design and build the hardware and software that goes into the SSD controller, but also the flash memory chips, unlike other storage companies that are forced to rely on third-parties for one or all of these aspects of their products.

This vertical approach means Samsung controls every aspect of its products, making it easier for the firm to introduce performance-boosting enhancements and custom technologies. And the 850 Pro is evidence that the company can bring these technologies to market sooner as well.

The 850 Pro represents the second generation of 3D V-NAND, as it debuted in enterprise SSDs, with 24 cells layered on top of each other. This time, Samsung has managed to layer 32 flash cells together.

Also worthy of note is that Samsung has added a 1TB option to its 850 Pro SSD line-up, which now includes 128GB, 256GB, 512GB and 1TB models. As with the 840 Pro, the drives are sold without any space reserved for over provisioning, a segment of the SSD that is usually reserved to improve longevity and performance. However, the user can implement this themselves using Samsung's Magician software.

The limitations of SATA

The main advantage of SSDs over mechanical hard disks is performance – but storage companies currently face a challenging problem. The SATA bus imposes a hard limit on the maximum possible sequential transfer rates. No matter how good the underlying technology, no SATA storage device can go faster than 6Gb/s. Even then, that's only a theoretical speed, and real-world performance is less.

The obvious answer is moving to a better, faster bus, and PCI-Express is the perfect candidate, since it significantly raises the bandwidth ceiling.

But this presents its own problems. Only desktop computers offer a standard way for users to add PCI-Express expansion cards, and there is no widely adopted standard on dimensions or connectors for laptops, which now command the lion's share of PC sales.

While Apple has been able to shift its entire Mac range to PCI-Express SSDs, since it has created its own proprietary connector, other firms don't have this luxury yet.

Life will become easier in the future with the introduction of the M.2 connector and NVM Express, a standard specification for PCI-Express SSDs in PCs that will replace AHCI and allow for much faster speeds.

But for now, the biggest market by far is with standard SATA storage devices, which is why Samsung has stuck to this standard with the 850 Pro. However, in terms of sequential transfer speeds, the 840 Pro was already approaching the limits of the SATA bus, so I wasn't expecting huge improvements with this aspect of performance in my tests.

Performance

Samsung claims that the 512GB 850 Pro can deliver 550MB/s sequential read speeds and 520MB/s sequential write speeds. In its documentation, the company further claims 100,000 IOPS during random 4K reads and 90,000 IOPS during writes.

With the 128GB 850 Pro, the sequential write speed drops to 470 MB/s, which is expected from smaller capacity SSDs, although it's an improvement over the 128GB 840 Pro model, which only managed 390 MB/s.

I tested the 850 Pro with two main software applications – Crystal Disk Mark and PCMark08, along with a few more synthetic benchmarks.

In Crystal Disk Mark, the sequential results confirmed Samsung's claims – exactly 550 MB/s reading and 525 MB/s writing.

IOPS (input/output operations per second) is a better indicator of storage performance than sequential speed, as it better shows the performance when writing small files. In daily use, a computer will spend more time reading and writing small files than large ones. These files could be spread all over the drive, unlike a large video which is more likely to be clumped together.

The 4K QD32 transfer rates are used to calculate IOPS. From a write speed of 326 MB/s, we arrive with a figure of 84,000 IOPS, slightly under Samsung's claim. But the read speed of 409 MB/s results in 104,000 IOPS. Many other brands of SSD manage no more than 60,000 IOPS.

Using a test PC with 8GB of memory and an Intel Core i5 2500K Sandy Bridge processor, PCMark 08 delivered a storage rating of 5,042 and an overall score of 3,884. A similar system with a much older and well-used Corsair Force 3 SSD managed 3,759 points, showing quite an improvement with the 850 Pro.

From these results, it's clear the 850 Pro leads the SSD market by a wide margin, in all aspects of performance.

Endurance

But so far, while the 850 Pro has proved itself to be a highly impressive SSD, we haven't yet seen the real fruits of Samsung's new technologies that differentiate the 850 Pro over its predecessor.

However, something particularly notable is buried within the 850 Pro's specification list. The drive is rated for a total of 150TB of writes, which translates to roughly 80GB/day for five years, or 40GB/day for ten years. This is double the endurance of the 840 Pro and considerably more than many other brands' SSDs.

For the unaware, SSDs have a limited lifespan. The cells can only be written to a number of times before they become unable to hold data, and are effectively dead. Although bear in mind, while this sounds like a horrific problem, even a low-end SSD has to be pushed hard to approach this limit.

Samsung backs this up with a hefty ten-year warranty, to match rival SanDisk's recently announced extended warranty on its Extreme SSD.

Samsung Magician

The final piece of the 850 Pro offering is some rather brilliant Windows SSD utility software dubbed Magician. The 850 Pro comes with version 4.4.

It performs multiple functions, offering common SSD maintenance tasks such as firmware updating and secure erase, which wipes your personal data and restores performance to (near) factory levels.

At a glance, the software will also tell you the health of your drive, the amount of storage being used and the amount of data that has been written to it, with full SMART diagnostic data just a click away. There's also a benchmarking tool.

It will also tell you if your system is optimised for SSD use, whether AHCI is enabled, and if various options are set in Windows. Rather than needing to remember how to turn these on via registry hacks or some setting in Control Panel, one click in Magician enables them.

But perhaps the best feature is something called Rapid 2.0, which reserves a portion of system memory as a write cache for the SSD, providing greatly improved bandwidth. You lose almost 1GB of system memory in exchange for much faster write speeds (although reading is unaffected). With version 4.4, if you have 8GB of system memory, Magician can reserve 2GB, improving performance further.

I tested this by first enabling Rapid mode, rebooting the PC then running Crystal Disk Mark again. It showed write speeds of 4.3GB/s, although the exact results may depend on your computer's specification.

The only concern with any RAM-based storage cache is the potential for data loss. Anything stored in RAM is lost when power is cut to the PC. Therefore if your PC crashes the very moment data is written to memory, but before it's been written to the SSD, which is by no means impossible, the data will be lost. Rapid mode is disabled by default, and this is the likely reason.

Verdict

We liked

The 850 Pro's performance and specification leads the market by a wide margin. It has the fastest sequential and 4K transfer rates of any SSD on the market. Clearly Samsung's end-to-end flash memory business is paying off for the company.

The improved endurance is especially welcome. Since the early days of SSD technology, owners have been told to avoid unnecessary writing to the disk if it can be helped, but this is steadily becoming less of a worry. The number of program erase cycles the 850 Pro can manage will mean the drive stays healthy for a considerable time.

A ten-year warranty is welcome as well, although in practice, it's likely that in ten years, technology will have moved on from the type of storage device the 850 Pro represents.

Finally the Magician software is definitely a positive thing to have, if only for the quick access to common SSD functions. Many other firms have their own similar software, such as Intel's SSD Toolbox, but not all.

We disliked

There really are few negative points to make about the 850 Pro, but if I had to pick one thing to grumble about, it would be the price. The 850 Pro costs roughly the same as the 840 Pro. You get a lot for your money, but it means system builders must choose between value and performance.

However, it also means other brands can still compete, and Samsung isn't handed complete domination of the market, a worrying position for consumers and manufacturers alike.

Final verdict

In the two years since Samsung launched the 840 Pro, other SSDs have managed to catch up with its sequential read and write speeds. To stay on top, Samsung has needed to offer more than just minimal performance improvements with the 850 Pro. Its high write endurance and better power consumption are just the ticket, leapfrogging what most consumer SSDs offer.

Coupled with the drive's high IOPS rating and excellent overall performance, the 850 Pro is a brilliant SSD and deserves an unequivocal recommendation. Anyone building a high-end PC should consider the 850 Pro as their SSD of choice. In professional media editing environments in particular, which will involve vast amounts of data being written to the drive, the 850 Pro should last considerably longer than other drives on the market.

That said, you're unlikely to see much of a real-world performance boost if you already have a high-end SSD, and we're not sure there's much reason to upgrade unless you're still using a hard disk for your main system drive, or your existing SSD is low on capacity or drive health.

But despite the increased competition, with the 850 Pro Samsung has showed it's still top of the game when it comes to solid-state storage.

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