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OCZ RevoDrive Review: SSD RAID + PCI-Express
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Date: Aug 10, 2010
Section:Storage
Author: Joel Hruska
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Introduction and Specifications

It's hard to remember that before the advent of SSDs, storage performance was a rather tepid topic. Save for the introduction of occasional new features like NCQ, hard drives continued along a mostly predictable path of rising capacities and (slightly) higher performance. If you wanted top-end performance, you bought a WD VelociRaptor or constructed a RAID config or arcane assembly of repurposed workstation and / or server-class hardware.



Now the market has flipped upside down. SSD manufacturers have been energetically rolling out new high-end, high-capacity products based around updated Indilinx, SandForce, or Marvell controllers, while simultaneously introducing smaller SSDs with better performance and lower prices than we saw with first-generation products. As SSDs become more popular and economical, we're seeing the rise of yet another consumer storage tier, over and above even the more expensive, high-performing SSDs:  Flash storage mated to PCI-Express. OCZ has launched its own product into the burgeoning sector—presenting the RevoDrive.



OCZ RevoDrive 120GB (842024018377)  2x SandForce 1200
Specifications & Features
Max Read: up to 540MB/s
Max Write: up to 480MB/s
Sustained Write: up to 400MB/s
Random Write 4KB (Aligned): 75,000 IOPS
Seek Time: 0.1ms
Interface:  PCIe x4
Power Consumption:  Idle 3W, Active 8W
Operating Temp: 0°C ~ 70°C
Storage Temp: -45°C ~ +85°C
Shock Resistant up to 1500G
RAID Support via Silicon Image 3124
Included 3.5" Desktop adapter bracket
Compatible with XP, Vista, 7, and Linux (32 and 64-bit flavors)
MTBF: 2 million hours
3-Year Warranty


Its features and specifications put the OCZ RevoDrive in lofty territory along with likes of Fusion-io's ioXtreme card. The RevoDrive's maximum read and write speeds far surpass any standard SSD currently on the market and its sustained and 4K random write ratings are also very impressive at 75K IOPS.
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Card Details

The RevoDrive's specs—up to 540MB/s read and 480MB/s writes—come courtesy of its onboard Silicon Image 3124 RAID controller. The card can be configured for RAID Level 0 or RAID Level 1; presumably most consumers will opt to utilize RAID 0 and provide an HDD-based backup solution. We're surprised to see the SiI 3124 putting in an appearance; the controller is over six years old and only supports PCI/PCI-X.


She may not look like much but she's got it where it counts...we hope.

It turns out, however, that this is one area where OCZ has cut cost to keep the RevoDrive affordable. The SiI 3124 connects directly to the Pericom PI7C9X130 bridge chip below it; it's this second processor that connects to the x4 PCI-Express slot. According to the company, it was cheaper to bridge the SiI 3124 than it was to buy a native controller; this decision is part of why the 120GB RevoDrive carries a price tag of just $369.


The Pericom bridge chip: Part of the RevoDrive's secret sauce.

The SiI 3124 should be adequate to the task at hand, but there are a few limitations to consider. Access latencies could be slightly higher, due to the use of a bridge chip, and the controller's PCI-X interface could cause oddities of its own. At 64-bits wide and an operating speed of 133MHz, the SiI 3124 RAID controller has a maximum throughput of 1.06GB/s(half-duplex). That's significantly less than the 800MB/s of full-duplex bandwidth a native PCIe x4 controller would've provided, but it shouldn't prove a problem in a two-drive RAID 0.


In the image above, the Silicon Image 3124 is underneath the stylized "R". The bridge processor is just below that. The center connector is an attach point for a second PCB—OCZ could release a four-way card at some point.

There are a few additional caveats. The drive doesn't support idle garbage collection and neither AHCI nor TRIM are available. Full AHCI support wasn't an original feature of the SiI 3124 (although Native Command Queuing, or NCQ, is supported). As for TRIM and garbage collection, the intervening RAID controller prevents either function from operating. 
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Meet the Competition, Cost Analysis


We've assembled a small group of drives to compare to the Revo, with several differing characteristics. Our comparison today is something of a SandForce party—the Corsair F100, GSkill Phoenix Pro (review soon), and the RevoDrive itself are all built around the SF-1200. Crucial is the odd man out; the C300 uses Marvell's 88SS9174-BJP2. The Marvell controller has only shown up in the C300 to date, and details on its design are hard to come by—Marvell doesn't list the controller or mention it on their website at all.


Rogues Gallery: GSkill, Crucial, and Corsair

The GSkill drive should also give us a gander at how the SF-1200 scales when we move from one to two controllers while keeping drive size identical, although the performance delta between the two could be affected slightly by the combined latency of the SiI 3124 controller and the bridge chip it relies on.

Cost Per Gigabyte: How Does Revo Rate?



The OCZ RevoDrive costs 38 percent more per GB than Crucial's C300 (although that drive is out-of-stock in a number of places), but the card's dual SF-1200 controllers should offer an excellent price/performance ratio. $400, however, is still a fair chunk of cash—the second-most-expensive drive, Corsair's F120, is over $100 cheaper for the same capacity.

We tossed in two hard drives to give you an idea of the relative costs. Given the dirt-low price of 1TB drives, we expect an increasing number of enthusiasts will switch to relatively small SSDs augmented by large storage arrays. At the same time, however, WD's 600GB VelociRaptor—unquestionably the fastest hard drive on the market—is less than a fifth as expensive as the cheapest SSD on our list. This suggests that WD can continue to eke out profitable sales on its high-performance HDDs--there's still a substantial gap in price per GB.
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Test System, HDTune

Our Test MethodologiesUnder each test condition, the Solid State Drives tested here were installed as secondary volumes in our testbed, with a standard spinning hard disk for the OS and benchmark installations.  The SSDs were left blank without partitions wherever possible, unless a test required them to be partitioned and formatted, as was the case with our ATTO, Vantage, and CrystalDiskMark benchmark tests. And all drives were secure erased prior to the start of any testing. Windows firewall, automatic updates and screen savers were all disabled before testing. In all test runs, we rebooted the system and waited several minutes for drive activity to settle before invoking a test.

HotHardware Test System
Intel Core i7 Powered

Processor -

Motherboard -


Video Card -

Memory -


Audio -

Hard Drives -

 

Hardware Used:
Intel Core i5-750


Gigabyte GA-P55-UD3R
(P55 Chipset)


ATI Radeon 5970

6144MB Corsair DDR3-1066


Integrated on board

WD Caviar Black 1TB (OS Drive)
Crucial C300 120GB
 GSkill Phoenix Pro 60GB
Corsair Force 100GB

OS -
Chipset Drivers -
DirectX -

Video Drivers
-


Relevant Software:
Windows 7 Ultimate
Intel 9.1.1.1025
DirectX 11

Catalyst 10.5

Benchmarks Used:
HD Tach v3.0.1.0
ATTO v2.46
CrystalDiskMark v3
PCMark Vantage
SiSoftware Sandra 2010 SP1

HD Tune 4.5
http://www.simplisoftware.com/

Given the age and limitations of HDTach, we've elected to adopt HDTune in its stead. HDTune is capable of performing a wide variety of performance tests—far more than HDTach—and can also be used to measure file system performance.



HD Tune's results still show the Revo way ahead of its competition, but the numbers look more like CrystalMark and less like SiSoft Sandra. Again, the gap between write performance is much smaller than read performance, though we should note that the majority of desktop scenarios mostly involve reads anyway. We should also note that modest, in this case, means a performance delta of 20-25 percent as compared to a 50-70 percent gain.
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SiSoft Sandra 2010


For our next set of tests, we used SiSoft SANDRA, the the System ANalyzer, Diagnostic and Reporting Assistant. Here, we used the Physical Disk test suite and provided the results from our comparison SSDs. Drives were erased prior to the run and tested in a non-partitioned state.
     
SiSoft SANDRA 2010
Synthetic Benchmarks


Of our three standard SSDs it's the Corsair F100 that turns in the highest overall scores—but none of the single-drives hold a candle to the Revo. Its real-world usefulness could be debated, but Sandra clearly likes what the Revo is serving. Compared to the GSkill Phoenix Pro the OCZ drive scales impressively—its MB/s transfer rate is 70 percent higher, while read performance jumped a whopping 85 percent.



We also kept an eye on drive write latency to see if the RevoDrive's additional controllers were penalizing the drive's performance. If they are, it's not by much—the C300 clocks up a surprising win here, but the Revo's 240ms access latency is still faster than the F100's 270. Based on our other results, it's clear that the penalty, if any, isn't enough to heavily impact the Revo's muscle.
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ATTO Disk Benchmark

ATTO is a more straight-forward type of disk benchmark that measures transfers across a specific volume length.  It measures raw transfer rates for both reads and writes and graphs them out in an easily interpreted chart.  We chose .5kb through 8192kb transfer sizes over a total max volume length of 256MB.  This test was performed on blank, formatted drives with NTFS partitions.

ATTO Disk Benchmark
Version 2.46

When comparing ATTO results, be advised that the Revo's performance is graphed against a theoretical 1000GB/s performance scale on the x-axis. That makes it more difficult to visually compare the results from the other drives--we'd recommend eyeballing the actual values. 


 
 


 
 


The C300 is far and away the fastest drive when we're moving very small amounts of data. Above 2K, however, the drive's overall performance begins to flag. Its Read Test throughput is significantly higher than the F100, but its write throughput doesn't scale at nearly the same rate. The C300 ties the GSkill for second place in terms of read performance, but is last in writes.

ATTO is another clear sweep for the Revo; the drive's read performance is a massive 90 percent higher than the GSKill Phoenix, its closest competitor. The write speed gap is smaller--but "just" 44 percent faster seems plenty fast to us. 
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CrystalDiskMark Benchmarks

CrystalDiskMark is another synthetic test we've started looking at that evaluates both sequential as well as random small and large file transfers.  It does a nice job of providing a quick look at best and worst case scenarios with SSD performance, best case being large sequential transfers and worse case being small, random 4K transfers.

CrystalDiskMark Benchmarks
Synthetic File Transfer Tests

Taken in aggregate, CrystalMark's test suite paints a confusing, contradictory picture of SSD performance. The Crucial C300 performs quite well in the sequential and 512K test, but falls away from the group during the 4K benchmarks. In the 4K Queue 32 test, the C300 splatters with a sound like dead whale chunks falling to the ground.

Results fluctuate between the OCZ Revo, the F100, and the Phoenix Pro. The differences between the GSkill and the Corsair drives mainly shows up in the write benchmarks but the performance gap between the two varies greatly depending on the test.

The Revo still leads the majority of the tests but its 512K write performance was only modestly higher than the SF-1200-equipped SSDs. 4K tests proved especially problematic; the Revo fell well behind the F100 and the Phoenix Pro. The 32-queue 4K tests were a different story—the Revo had no problem outclassing its opponents, although again, the write performance increase was modest. The C300 performed exceptionally well, here, far outpacing the other two drives. 

 

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PCMark Vantage

Next we ran the three drives through a battery of tests in PCMark Vantage from Futuremark Corp. We specifically used only the HDD Test module of this benchmark suite to evaluate all of the drives we tested. Feel free to consult Futuremark's white paper on PCMark Vantage for an understanding of what each test component entails and how it calculates its measurements. For specific information on how the HDD Test module arrives at its performance measurements, we'd encourage you to read pages 35 and 36 of the white paper.

Futuremark's PCMark Vantage
http://www.futuremark.com

We really like PCMark Vantage's HDD Performance for its real-world application measurement approach to testing.  From simple Windows Vista start-up performance to data streaming from a disk drive in a game engine and video editing with Windows Movie Maker, we feel confident that these tests best illustrate the real performance profile of our SSDs in an end user/consumer PC usage model.


The RevoDrive is in its element in this selection of read-heavy benchmarks. Save for the import pictures test, where it's just 18 percent ahead of the GSkill, it clobbers everyone with 50-75 percent higher performance. These are the sorts of real-world tests that showcase the Revo's strongest points; OCZ obviously dosed the drive with Vitamin Whoopass before releasing it.

 

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PCMark Vantage (Cont)

With the exception of the Application Loading benchmark, the next series of Vantage tests will stress write performance. Applications like video editing, streaming and recording are not what we would call a strong suit for the average SSD, due to their high mix of random write transactions.

Futuremark's PCMark Vantage
http://www.futuremark.com

We should also note that it's not so much a weakness of the memory itself, but rather the interface and control algorithms that deal with inherent erase block latency of MLC NAND flash.  SSD manufacturers are getting better at this, but comparative results can vary widely.

We've organized this graph according to test rather than by drive. It should be easier to make comparisons between drives in any given test, as well as to eyeball overall performance. Let us know what you think and if you prefer this method.

The C300 is a perfect example of how rapidly SSD technology is evolving. While it keeps pace reasonably well with the SandForce drives, it still falls into last place overall. On the other hand, it still turns in numbers that would turn a hard drive's motor into melted slag.

The Phoenix Pro rather handily beats the F100; losing to it by a comparative inch in just one test. As for the Revo, it wins every test--but once again, we see evidence that the drive's write performance fluctuates. In Media Center and Movie Maker it's just 10 percent and 12 percent faster than the single-controller GSkill.  Application Loading and Media Player tests show better numbers--here the RevoDrive is 42 percent and 31 percent above its competition.
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Conclusion


Performance Summary: It's just this simple: the RevoDrive rocks. Taken in aggregate, the drive's price/performance ratio is virtually identical to its competitors—it costs ~33 percent more than Corsair's F100 but offers performance roughly 30 percent higher, depending on the benchmark. Be aware that this ratio will swing a bit depending on your personal usage patterns--in some cases the RevoDrive offers a better price/performance ratio than any of the drive's we tested--and in a few tests it's just 10-20% faster. The former occurs considerably more than the latter, which is part of why we like the drive.

 

When we reviewed the PCIe X4 Fusion-io Xtreme/Xtreme Pro nine months ago we took particular notice of the card's price—the XDrive cost $11.18 per GB while the XDrive Pro was a steep $9.36 per GB. In less than a year, OCZ slashed more than half off the price premium on PCI-Express storage, brought the RevoDrive almost in line with standard SSD drives, offers a three-year warranty, and it's bootable. That, ladies and gentlemen, is as good as it gets.  That said, if you compare the numbers loosely from our review back then, the ioXtreme does still hold a performance edge in spots.

While it's true that the RevoDrive lacks TRIM support, that's the current price of admission if you want to run a RAID array. There's no evidence that this is going to change—various companies, including Intel, are apparently "working" on the problem, but no one has come up with a software solution yet. RAID-level TRIM support may not be possible until new controllers are designed to support it.  In other words, don't buy a Revo now with the expectation that updated drivers will come along and add this particular function.

Without these capabilities, the drive's performance will inevitably degrade over time, but its high base performance should keep it out in front of its SSD competitors even when dirty. It's also possible to minimize the drive's performance penalty by periodically imaging one's OS installation, reformatting the Revo from inside the SiI 3124 RAID BIOS, and then re-creating the array. 

We'd recommend the RevoDrive to anyone looking for top-notch performance. The Revo has set a new bar for both SSDs and RAID-based PCI-Express storage cards.  We look forward to seeing how the rest of the industry responds. 

 

  • Extreme Performance
  • Bootable PCIe Card
  • More Affordable Than Other PCIe-Based Storage Solutions

  • Relatively Expensive
  • Silicon Image Controller + PCIe Bridge Adds Some Latency
  • No TRIM Support



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