OCZ’s Arc 100 solid-state drive reviewed

The steady decline in SSD prices has been one of the most fascinating trends of the past few years. Shrinking flash fabrication technologies deserve the bulk of the credit for lowering the cost per gigabyte. However, OCZ also played a role by aggressively discounting its SSDs, which fueled a price war that hasn’t fully subsided since.

Those discounts surely contributed to OCZ’s former financial difficulties. The company filed for bankruptcy last year, and it was subsequently acquired by Toshiba. All things considered, that’s probably the best thing that could have happened. Toshiba is one of the biggest flash manufacturers in the world, and OCZ now has preferred access to the latest and greatest NAND—probably with family discount.

OCZ is making the most of that access with its new Arc 100 SSD. This drive, based on the Barefoot controller, uses the most recent “A19” revision of Toshiba’s 19-nm NAND. It’s also eminently affordable, with the 240GB and 480GB flavors priced at just $0.50 per gig.

Despite its budget focus, the Arc 100 is supposed to deliver especially strong performance with more demanding and sustained workloads. More importantly, perhaps, there’s evidence that OCZ’s reliability track record has improved since the firm was purchased by Toshiba. This thing deserves a closer look.

Another Barefoot remix
OCZ’s proprietary Barefoot 3 controller sits inside the Arc 100. That chip has dual cores; one is an off-the-shelf ARM Cortex unit, while the other is an “Aragon” co-processor designed by OCZ. The controller is fairly conventional otherwise, with eight parallel NAND channels and a 6Gbps Serial ATA host interface.

We first saw the Barefoot 3 in OCZ’s Vector SSD way back in 2012. A slower “M10” revision of the controller powered last year’s Vertex 450 and its successor, the Vertex 460. The Arc 100 also uses the M10 chip, but the clock frequency has been dialed back 15% versus the implementation in the Vertex 460.

On the encryption front, the controller can scramble data in hardware using a 256-bit AES algorithm. However, support for the related IEEE and TCG Opal specifications is missing from the Arc 100’s feature list, which rules out compliance with Microsoft’s eDrive standard and third-party encryption management software. That’s a bummer for corporate users, but the omission probably won’t bother typical consumers.

The NAND is two-bit MLC stock built on the second generation of Toshiba’s 19-nm fabrication process. These A19 chips have narrower dies than their predecessors, allowing more of them to be packed onto each silicon wafer. Toshiba has been using A19 NAND in its own SSDs since earlier this year, and now OCZ is getting in on the action.

All the members of the Arc 100 family employ 8GB flash dies. Most controllers require at least 32 dies to hit top speed, so the 120GB version of the Arc has slightly lower performance specifications than its larger siblings. Here’s how the line stacks up:

The runt of the family doesn’t suffer as much as one might expect. There’s only a slight reduction in sequential speeds, and the peak random I/O rates are the same regardless of the capacity. However, the 120GB unit takes a big hit in sustained random write performance. That metric may be influenced more by the amount of overprovisioned spare area than by the number of parallel NAND dies. All the drives allocate the same percentage of their total flash capacity to overprovisioned area that can be used by the controller to accelerate write performance. Since the higher-capacity variants have more capacity to start, the end up with more “spare area” for the controller.

In any case, the 120GB version has a higher cost per gig than the others. You may want to avoid it on that basis alone.

Like a lot of consumer-grade SSDs, the Arc 100 is rated for 20GB of writes per day for the length of its three-year warranty. That works out to 22TB in total, which should be plenty of headroom for most client workloads. You can probably write a lot more to the drive, too. The results of our ongoing endurance experiment suggest that modern SSDs can write hundreds of terabytes without issue.

In an interesting twist, the Arc 100 comes with a new ShieldPlus warranty that’s supposed to simplify the return process. If users encounter problems with their drives, they need only provide the serial number—no proof of purchase is necessary. OCZ’s support reps will try to rectify the problem remotely, and if they can’t, they’ll ship out an advance replacement unit with a pre-paid return label in the box. The ShieldPlus warranty will initially be offered only in North America and the EMEA region (Europe, the Middle East, and Africa), but its scope will expand to other regions in the future.

We can’t discuss warranty coverage without mentioning OCZ’s somewhat checkered reliability track record. Much of that is well in the past, but even the user reviews for some of the company’s earlier Barefoot 3-based drives are filled with complaints about DOA units and premature failures. Happily, though, the tide appears to be turning. The Amazon and Newegg user reviews for OCZ’s more recent Vector 150 and Vertex 460 have fewer reports of problems than we’ve seen in the past. The percentages of one-star and otherwise negative ratings are also lower than for some of OCZ’s older SSDs.

Online user reviews need to be taken with a grain of salt, of course, and OCZ’s more recent drives aren’t rated as highly as some of their competition. Still, the anecdotal evidence suggests progress is being made on the reliability front. The internal data OCZ shared with us also shows a reduction in failure rates:

According to OCZ, the Vertex 150 and Vertex 460 have much lower return and failure rates than previous generations. The firm credits its switch to in-house controller technology for some of the improvement, and it says getting early access to Toshiba NAND has also helped “to further improve performance and reliability.” If these numbers are accurate, the failure rates for OCZ’s most recent SSDs are lower than for Intel’s business-oriented drives. Seems almost too good to be true.

Unfortunately, reliability isn’t something we can easily evaluate independently. But we can quantify the Arc 100’s performance in a varied collection of tests—and against a wide range of alternatives. Our performance analysis starts on the next page.

CrystalDiskMark — transfer rates
TR regulars will notice that we’ve trimmed a few tests from our usual suite of storage results. The drives were all benchmarked in the same way, but we’ve excluded the results for tests that have grown problematic or less relevant over time. This abbreviated format should be a little easier to digest until our next-gen storage suite is ready.

First, we’ll tackle sequential performance with CrystalDiskMark. This test runs on partitioned drives with the benchmark’s default 1GB transfer size and randomized data.

We’ve color-coded the results to make the OCZ drives—and the Arc 100—easier to pick out of the fray. OCZ sent us the 240GB version of the Arc, which sells for only about five bucks more than Crucial’s MX100 256GB. Since the MX100 is our favorite budget SSD, we’ve also colored the results for that drive. We’ll be watching the battle between it and the Arc 100 closely.

Not counting the mechanical drives, which represent a whole other class of PC storage, the Arc 100 has the slowest sequential read speed of the bunch. There’s apparently no need to worry about it bumping into the limits of the Serial ATA interface.

The Arc 100 is more competitive in the sequential write speed test, where it beats the equivalent MX100 and a bunch of other SSDs. However, OCZ’s latest budget contender is still behind the bulk of the field, including drives based on the same Barefoot silicon.

HD Tune — random access times
Next, we’ll turn our attention to random access times. We used HD Tune to measure access times across multiple transfer sizes. SSDs have near-instantaneous seek times, so it’s hard to graph the results on the same scale as mechanical drives. The WD Black and Seagate SSHD will sit out this round to focus our attention on the SSDs.

In most of these tests, the differences amount to tiny fractions of a millisecond. You’re probably not going to notice.

The field spreads out a bit more in the 1MB random write test, though, and the Arc 100 takes full advantage. It’s quicker than both the MX100 256GB and the other OCZ offerings. Didn’t see that one coming. Perhaps the Arc’s A19 NAND is responsible.

TR FileBench — Real-world copy speeds
FileBench, which was concocted by TR’s resident developer Bruno “morphine” Ferreira, runs through a series of file copy operations using Windows 7’s xcopy command. Using xcopy produces nearly identical copy speeds to dragging and dropping files using the Windows GUI, so our results should be representative of typical real-world performance. We tested using the following five file sets—note the differences in average file sizes and their compressibility. We evaluated the compressibility of each file set by comparing its size before and after being run through 7-Zip’s “ultra” compression scheme.

The names of most of the file sets are self-explanatory. The Mozilla set is made up of all the files necessary to compile the browser, while the TR set includes years worth of the images, HTML files, and spreadsheets behind my reviews. Those two sets contain much larger numbers of smaller files than the other three. They’re also the most amenable to compression.

To get a sense of how aggressively each SSD reclaims flash pages tagged by the TRIM command, the SSDs are tested in a simulated used state after crunching IOMeter’s workstation access pattern for 30 minutes. The drives are also tested in a factory fresh state, right after a secure erase, to see if there is any discrepancy between the two states. There wasn’t much of one with the Arc 100, so we’re only presenting the used-state scores.

This is why I like using multiple sets with different kinds of files. The Arc 100 has higher copy speeds than the competing MX100 with larger video, music, and image files. However, the Crucial drive comes out ahead with the smaller and more numerous files in the Mozilla and TR sets.

Plenty of other affordable SSDs are faster than the Arc 100 overall, including the Samsung 840 EVO. The EVO is notably more expensive, though. Among the drives we’ve assembled, only the MX100 matches the Arc’s bargain pricing.

TR DriveBench 2.0 — Disk-intensive multitasking
DriveBench 2.0 is a trace-based test comprised of nearly two weeks of typical desktop activity peppered with intense multitasking loads. More details on are available on this page of our last major SSD round-up.

We measure DriveBench performance by analyzing service times—the amount of time it takes drives to complete I/O requests. Those results are split into reads and writes.

The Arc 100 performs very well in what’s arguably our most important benchmark. Its mean read service time is good enough to place it in the middle of the pack, and its mean write service time is the third-quickest overall.

Most of the SSDs are closely matched in the read results, so I wouldn’t pay too much attention to the fact that the Arc 100 comes out ahead of its MX100 rival. The Arc’s mean write service time is 4X quicker than the MX100’s, though. Its write service times are also much more consistent. The OCZ drive’s standard deviation for writes, which describes the degree of variance, is less than one-seventh that of the Crucial alternative.

All the SSDs execute the vast majority of DriveBench requests in one millisecond or less—too little time for end users to perceive. We can also sort out the number of service times longer than 100 milliseconds, which is far more interesting data. These extremely long service times make up only a fraction of the overall total, but they’re much more likely to be noticeable.

Again, the Arc 100 lays a beating on the equivalent MX100. The OCZ SSD has about a third fewer extremely long read service times. It also logs just 24 sluggish writes, compared to over 46,000 for the MX100 256GB.

OCZ often boasts about its SSDs being tuned for consistent performance over the long haul, and our DriveBench results show that the swagger is warranted. The Arc 100 beats a lot of much pricier alternatives.

IOMeter
Our IOMeter workload features a ramping number of concurrent I/O requests. Most desktop systems will only have a few requests in flight at any given time (87% of DriveBench 2.0 requests have a queue depth of four or less). We’ve extended our scaling up to 32 concurrent requests to reach the depth of the Native Command Queuing pipeline associated with the Serial ATA specification. Ramping up the number of requests also gives us a sense of how the drives might perform in more demanding enterprise environments.

We run our IOMeter test using the fully randomized data pattern, which presents a particular challenge for SandForce’s write compression scheme. We’d rather measure SSD performance in this worst-case scenario than using easily compressible data.

There’s too much data to show clearly on a single graph, so we’ve split the results. You can compare the performance of the Arc 100 to that of the competition by clicking the buttons below each graph.

Instead of presenting the results of multiple access patterns, we’re concentrating on IOMeter’s database test. This access pattern has a mix of read and write requests, and it’s similar to the file server and workstation tests. The results for these three access patterns are usually pretty similar. We also run IOMeter’s web server access pattern as part of our standard suite of tests, but it’s made up exclusively of read requests, so the results aren’t as applicable to real-world scenarios. Our own web servers log a fair amount of writes, for example.

OCZ’s latest Barefoot 3 SSDs hit higher peak I/O rates than even Intel’s datacenter-derived 730 Series. Well, the 240GB ones do, anyway. The Vertex 450 256GB has much lower throughput, likely because its higher user-accessible capacity leaves less overprovisioned area for the controller.

The Arc 100 doesn’t really hit its stride until the number of concurrent requests climbs above four, but it’s still faster than most of the competition until that point. Other budget contenders, like the Crucial MX100 256GB and Samsung 840 EVO 250GB, are simply outclassed.

Boot duration
Before timing a couple of real-world applications, we first have to load the OS. We can measure how long that takes by checking the Windows 7 boot duration using the operating system’s performance-monitoring tools. This is actually the first test in which we’re booting Windows off each drive; up until this point, our testing has been hosted by an OS housed on a separate system drive.

Level load times
Modern games lack built-in timing tests to measure level loads, so we busted out a stopwatch with a couple of titles.

Zzzzz.

Sorry, I nodded off for a second there. The SSDs are all within about a second of each other, making the differences between them difficult to discern in practice.

We’re working on an updated batch of load-time tests for our next-gen storage suite. Shoot me an email if you have any suggestions. (And thanks to those who have already chimed in.)

Power consumption
We tested power consumption under load with IOMeter’s workstation access pattern chewing through 32 concurrent I/O requests. Idle power consumption was probed one minute after processing Windows 7’s idle tasks on an empty desktop.

The Arc 100 has reasonably low power consumption at idle and under load. The 0.1-0.2W gaps between it and the MX100 aren’t likely to result in substantial differences in notebook battery life.

That’s it for performance. If you’re curious about the other SSDs in this review or about how we conduct our testing, hit up the methods section on the next page. Otherwise, feel free to skip ahead to the conclusion.

Test notes and methods
Here’s a full rundown of the SSDs we tested, along with their essential characteristics.

	Cache	Flash controller	NAND
Adata SP920 512GB	512MB	Marvell 88SS9189	20nm Micron sync MLC
Corsair Force Series GT 240GB	NA	SandForce SF-2281	25nm Intel sync MLC
Corsair Neutron 240GB	256MB	LAMD LM87800	25nm Micron sync MLC
Corsair Neutron GTX 240GB	256MB	LAMD LM87800	26nm Toshiba Toggle MLC
Crucial M500 240GB	256MB	Marvell 88SS9187	20nm Micron sync MLC
Crucial M500 480GB	512MB	Marvell 88SS9187	20nm Micron sync MLC
Crucial M500 960GB	1GB	Marvell 88SS9187	20nm Micron sync MLC
Crucial M550 256GB	256MB	Marvell 88SS9189	20nm Micron sync MLC
Crucial M550 512GB	512MB	Marvell 88SS9189	20nm Micron sync MLC
Crucial M550 1TB	1GB	Marvell 88SS9189	20nm Micron sync MLC
Crucial MX100 256GB	256MB	Marvell 88SS9189	16nm Micron sync MLC
Crucial MX100 512GB	512MB	Marvell 88SS9189	16nm Micron sync MLC
Intel 335 Series 240GB	NA	SandForce SF-2281	20nm Intel sync MLC
Intel 520 Series 240GB	NA	SandForce SF-2281	25nm Intel sync MLC
Intel 730 Series 480GB	1GB	Intel PC29AS21CA0	20nm Intel sync MLC
OCZ Vertex 4 256GB	512MB	Indilinx Everest 2	25nm Micron sync MLC
OCZ Vertex 450 256GB	512MB	Indilinx Barefoot 3 M10	20nm Micron sync MLC
OCZ Vertex 460 240GB	512MB	Indilinx Barefoot 3 M10	19nm Toshiba Toggle MLC
OCZ Arc 240GB	512MB	Indilinx Barefoot 3 M10	A19nm Toshiba Toggle MLC
SanDisk Extreme II 240GB	256MB	Marvell 88SS9187	19nm SanDisk Toggle SLC/MLC
Samsung 840 Series 250GB	512MB	Samsung MDX	21nm Samsung Toggle TLC
Samsung 840 EVO 250GB	256MB	Samsung MEX	19nm Samsung Toggle TLC
Samsung 840 EVO 500GB	512MB	Samsung MEX	19nm Samsung Toggle TLC
Samsung 840 EVO 1TB	1GB	Samsung MEX	19nm Samsung Toggle TLC
Samsung 840 Pro 256GB	512MB	Samsung MDX	21nm Samsung Toggle MLC
Samsung 850 Pro 512GB	512MB	Samsung MEX	32-layer Samsung V-NAND
Seagate 600 SSD 240GB	256MB	LAMD LM87800	19nm Toshiba Toggle MLC
Seagate Desktop SSHD 2TB	64MB	NA	24nm Toshiba Toggle SLC/MLC
WD Caviar Black 1TB	64MB	NA	NA

Our main body of results contains some of the most popular SSDs around. The bulk of the field is in the 240-256GB range, and most of those drives have 32-die configurations with no performance handicaps. For the Crucial M500, M550, MX100, and Samsung 840 EVO, whose lower-capacity flavors are tagged with slower specs, we have results for multiple capacities, including the fastest models. You can find full reviews of most of the drives in our storage section.

The solid-state crowd is augmented by a couple of mechanical drives. WD’s Caviar Black 1TB represents the old-school hard drive camp. Seagate’s Desktop SSHD 2TB is along for the ride, as well. The SSHD combines mechanical platters with 8GB of flash cache, but like the Caviar Black, it’s really not a direct competitor to the SSDs. The mechanical and hybrid drives are meant to provide additional context for our SSD results.

If you made it this far, you might enjoy a close-up of the Arc 100’s naked circuit board.

Oooh, sexy.

We used the following system configuration for testing:

Thanks to Asus for providing the systems’ motherboards and graphics cards, Intel for the CPUs, Corsair for the memory and PSUs, Thermaltake for the CPU coolers, and Western Digital for the Caviar Black 1TB system drives.

We used the following versions of our test applications:

• Intel IOMeter 1.1.0 RC1
• HD Tune 4.61
• TR DriveBench 1.0
• TR DriveBench 2.0
• TR FileBench 0.2
• Qt SDK 2010.05
• MinGW GCC 4.4.0
• Duke Nukem Forever
• Portal 2

Some further notes on our test methods:

• To ensure consistent and repeatable results, the SSDs were secure-erased before almost every component of our test suite. Some of our tests then put the SSDs into a used state before the workload begins, which better exposes each drive’s long-term performance characteristics. In other tests, like DriveBench and FileBench, we induce a used state before testing. In all cases, the SSDs were in the same state before each test, ensuring an even playing field. The performance of mechanical hard drives is much more consistent between factory fresh and used states, so we skipped wiping the HDDs before each test—mechanical drives take forever to secure erase.

• We run all our tests at least three times and report the median of the results. We’ve found IOMeter performance can fall off with SSDs after the first couple of runs, so we use five runs for solid-state drives and throw out the first two.

• Steps have been taken to ensure that Sandy Bridge’s power-saving features don’t taint any of our results. All of the CPU’s low-power states have been disabled, effectively pegging the 2500K at 3.3GHz. Transitioning in and out of different power states can affect the performance of storage benchmarks, especially when dealing with short burst transfers.

The test systems’ Windows desktop was set at 1280×1024 in 32-bit color at a 75Hz screen refresh rate. Most of the tests and methods we employed are publicly available and reproducible. If you have questions about our methods, hit our forums to talk with us about them.