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OCZ Z-Drive R4 PCIe SSD Performance Preview
Date: Sep 27, 2011
Author: Dave Altavilla
Introduction and Specifications
A few months back, OCZ took the wraps of their RevoDrive 3 product line. The RevoDrive 3 was the first product to make use of what OCZ calls their SuperScale Storage Accelerator processor with VCA 2.0, or Virtualized Controller Architecture. In short, coupled with a quartet of SandForce SF-2200 series SSD controllers, OCZ's VCA technology really turns up the juice on their new PCI Express-based SSD solutions; so much so that this "prosumer" or performance workstation class product actually leaves far more expensive enterprise class PCIe SSDs in the dust.

Today, OCZ is letting fly with the second coming of a VCA 2.0 product, this time squarely targeting the enterprise, datacenter and high-end workstation markets.  Where OCZ's RevoDrive line targets more consumer-like price points, the Z-Drive line is about no holds barred performance for the enterprise. The Z-Drive R4 with VCA 2.0, the same SuperScale Storage Accelerator, and now an octet of SandForce SF-2200 series controllers, has landed on our testbeds for a few cycles of the benchmark gauntlet.  And oh yeah, it's packing a full 1.6TB (yes, that's Terabytes) of usable capacity on board.  As the old saying goes, let the games begin!

Specifications & Features
Performance Specifications:
  • Max Read: 2800 MB/s
  • Max Write: 2800 MB/s
  • 4KB Random Write: 440,000 IOPS (QD:128, 4K Aligned, 8GB LBA)
  • Available in 800GB, 1.6TB, and 3.2TB configurations
Key Features:
  • PCI Express SSD (PCIe Gen2 x8) designed to deliver ultra-high performance for server and high performance computing (HPC) environments
  • Bootable drive (unique from competing solutions) so users can enjoy enhanced OS performance
  • OCZ SuperScale storage accelerator enables scalable SSD performance and reduces the host CPU burden inherent to competing PCIe solutions. This controller, combined with VCA 2.0, provides unique benefits to the user by allowing certain DMA and data management functions including OCZ’s unique Complex Command Queuing Structure and Queue Balancing Algorithms to be handled by the storage virtualization layer, resulting in higher drive performance and minimized burden on the host CPU.
  • Implements multiple SandForce 2200 series controllers for greater performance and endurance.
  • Cost-effective 25nm MLC flash with enhanced reliability
  • Z-Drive R4 runs optimally with 100 Linear Feet per Minute (LFM) of airflow.
  • Lower power consumption: 23W idle, 26W active
Pricing and Warranty:
  • $5 - $7 per GB - Final MSRP still TBD
  • 2,000,000 hour MTBF
  • 3 Year Warranty

Your eyes aren't deceiving you and yes, you're doing the math right.  That's 2.8GB/s for max read bandwidth and 2.8GB/s of max write bandwidth. For those of you on the datacenter side of things, that 440K IOPs spec ought to slacken the jaw a bit as well.  These are lofty claims to be sure for the Z-Drive R4. However, when there are eight total SandForce SF-2200 chips at play, along with Intel's fastest 25nm Flash technology and OCZ's new SuperScale processor, across a 5Gbps PCI Express Gen 2 x8 interface, impressive things can happen. 

Copious bandwidth, native, high-speed serial interfaces and a load balancer; this is essentially what makes up the OCZ Z-Drive R4.  Here we'll try to determine if the Z-Drive R4 offers the kind of performance that equals the sum of its high-end components.
The OCZ Z-Drive R4
As we noted previously, the Z-Drive R4 is based on the very same chip-level technology that OCZ's RevoDrive 3 series employs. Though the RevoDrive 3's that we've looked at thus far are based on Micron NAND Flash, the Z-Drive R4 is built upon Intel 25nm chips.  These chips specifically are 16GB density (128Gbits X 8).  There are a total of 128 chips on the two PCBs of the Z-Drive R4 that we tested, for a total of 1.6TB of useable capacity, with an actual total of 2TB of NAND, with that spare capacity over-provisioned for maintenance and wear-leveling algorithms.

Full Length PCI Express PCB, X8 Gen 2 Edge Connector and a Prodigious Amount of Flash

Beyond fast, low power Intel Flash, what really drives the Z-Drive R4 is OCZ's SuperScale processor (the chip sitting beneath the small black heatsink).  We won't delve too much into this device since we covered it in detail in our RevoDrive 3 X2 review here. Suffice it to say that the SuperScale Storage Accelerator acts as a Traffic Cop and load balancer of sorts channeling requests to the eight SandForce SF-2200 chips on the top and base PCBs.  OCZ's proprietary VCA 2.0 (Virtuatlized Controller Architecture) supports both SandForce's garbage collection algorithms as well as TRIM and SMART monitoring functions.  However, since VCA uses the SCSI protocol and the Windows StorPort architecture doesn't support TRIM or SCSI UNMAP, TRIM commands aren't generated by Windows to the drive.  OCZ is working with Microsoft on this and hopes to have TRIM enabled "as soon as possible."

Power and Cooling:
Beyond Intel's Flash, the SF-2200 controllers, the SuperScale processor and a few power regulation circuits, there is a small Lattice PLD (Programmable Logic Device) that functions as a power monitor and sequencer for the Z-Drive R4.  With the complexity of these PCBs, power control and timing has to be precise.

Speaking of which, this leads us to something that closely correlates to power -- heat.  Though OCZ states max power consumption for the Z-Drive R4 is 26 Watts, it's our humble opinion that the cooling solution for their SuperScale Storage Accelerator isn't quite as robust as we would like to see. We had detailed dialog with OCZ on this topic and their specified 100 LFM (Linear Feet Per Minute) airflow requirement for the Z-Drive R4.  Though we didn't measure airflow across the board, in our test system it required direct external cool airflow over the board to keep it stable.  Standing at ambient room temperature, on an open air test bench, the board was not stable either. In fact, under the strain of our IOMeter tests, we had to dial cooling fans up high to provide adequate cooling.

We've also noted the same sensitivity to heat with the OCZ RevoDrive 3, though it's not as particular about airflow as the Z-Drive R4.  However, if you sandwich the RevoDrive 3 in between two high-end graphics cards in SLI or CrossFire (a common setup for high end gaming or workstation systems), you better have a side intake fan pulling cool air in over the board.

However, we should underscore that the Z-Drive R4 is targeted for high-end workstations, but even more-so for datacenter applications with server platforms and high airflow chassis.  In this application and usage model, the Z-Drive should get adequate airflow and remain stable.  Regardless, we would have liked to see a more robust cooling solution on the product.  In fact, OCZ has noted that their Engineering team is already working on a new cooling solution.

Alright then, benchmarks anyone?
Test System SANDRA Physical Disk Tests

Our Test Methodologies: Under each test condition, the SSDs tested here were installed as secondary volumes in our testbed, with a standard spinning hard disk for the OS and benchmark software 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, as well as one of the IOMeter runs. 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 and SSD Powered

Processor -

Motherboard -

Video Card -

Memory -

Audio -

Hard Drives -

Hardware Used:
Intel Core i7-970

Intel DX58SO2
(X58 Chipset)

NVIDIA GeForce GTX 285

6144MB Kingston DDR3-1333

Integrated on board

WD Caviar Black 1TB (OS Drive)
OCZ RevoDrive 3 X2 480GB PCIe
LSI WarpDrive 300GB PCIe
OCZ RevoDrive X2 240GB PCIe
OCZ RevoDrive 120GB PCIe
Fusion-io ioDrive 160GB
Fusion-io ioXtreme 80GB PCIe
OCZ Z-Drive R4 1.6TB PCIe

OS -
Chipset Drivers -
DirectX -

Video Drivers

Relevant Software:
Windows 7 Ultimate x64
DirectX 11

NVIDIA GeForce, latest WHQL

Benchmarks Used:
IOMeter 2010
ATTO v2.46
CrystalDiskMark v3.1
PCMark Vantage
SiSoftware Sandra 2011
HH Custom File Transfer Tests

SiSoft SANDRA 2011
Synthetic HDD Benchmarking

For our first 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. The benchmarks were run without formatting and read and write performance metrics are detailed below.

What can we say that this benchmark results chart doesn't already?  In the quick-take sequential transfer measurements that SANDRA pushes to the SSDs in our test run, the Z-Drive R4 is over two time faster than the Fusion-io ioDrive in both read and write throughput.  The only drive that comes close to the R4 is the OCZ RevoDrive 3.  That's what you call a happy performance graph.


IOMeter Test Results

As we've noted in our previous SSD coverage, though IOMeter is clearly a well-respected industry standard drive benchmark, we're not completely comfortable with it for testing SSDs. The fact of the matter is, though our results with IOMeter appear to scale properly with workload, it is debatable whether or not certain access patterns, as they are presented to and measured on an SSD, actually provide a valid example of real-world performance.  That said, we do think IOMeter is a gauge for relative available bandwidth and response throughput for a given storage solution. In addition there are certain higher-end workloads you can invoke on a drive with IOMeter, that you really can't with any other benchmark tool available currently.

 I/O Subsystem Measurement Tool

In the following tables, we're showing two sets of access patterns; our Workstation pattern, with an 8K transfer size, 80% reads (20% writes) and 80% random (20% sequential) access and our Database access pattern of 4K transfers, 67% reads (34% writes) and 100% random access.

Under very light workloads, the Z-Drive R4 offers midland performance and doesn't push past Fusion-io's competitive enterprise SLC-based ioDrive.  However, turn up the requests and the Z-Drive R4 really screams.  Though our more read-intensive 8K Workstation test shows a slightly wider performance spread for the new Z-Drive, overall OCZ's solution offers more than two times the IO throughput versus the far more expensive (on a per GB basis) Fusion-io product under these test conditions.

ATTO Disk Benchmark
ATTO is another quick-take type of synthetic disk benchmark that measures transfer speeds 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 and a queue depth of 10 over a total max volume length of 256MB. ATTO's workloads are sequential in nature and measure raw bandwidth, rather than IO response time or access latency. This test was performed on blank, formatted drives with default NTFS partitions in Windows 7 x64.

ATTO Disk Benchmark

Fusion-io ioXtreme 80GB PCI Express SSD

Fusion-io ioDrive 160GB

LSI WarpDrive 300GB

OCZ RevoDrive 3 X2

OCZ Z-Drive R4

What ATTO shows us is that, at very small transfer sizes (.5  - 4K), the Z-Drive R4 is pretty much on par with competitive solutions. Again, this test is what we'd call a light workload, with a queue depth of only 10.  However, as transfers increase past 8K or so, the Z-Drive R4 once again begins to blow everything else out of the water.  We were actually able to slightly exceed OCZ's max read and write bandwidth specs and topped out at 2.92GB/s and 2.71GB/s for reads and writes, respectively.  The Z-Drive R4 has exhibited far and away the best performance we've seen in every test we've thrown at it thus far.  Previously, the best ATTO scores we've seen came from the OCZ RevoDrive 3.  The Z-Drive R4 more than doubled its performance.  Simply impressive.

CrystalDiskMark Performance

CrystalDiskMark is a synthetic benchmark that tests 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 regard to SSD performance, best case being larger sequential transfers and worse case being small, random transfers.

CrystalDiskMark Benchmarks
Synthetic File Transfer Tests

OCZ Z-Drive R4

Fusion-io - 80GB MLC

Fusion-io ioDrive 160GB SLC

OCZ RevoDrive X2 240GB MLC

LSI WarpDrive 300GB SLC

OCZ RevoDrive 3 X2 480GB

The song remains the same, to quote a Zeppelin title.  In sequential and large transfers, the Z-Drive R4 rips every other competitive score to shreds. In small 4K random transfers, the R4 shows competitive write throughput but comes up short in reads versus the Fusion-io card, again with light duty workloads and queue depths.  At the 4K and 32 queue depth setup, the Z-Drive R4 drops in behind the more expensive SLC NAND-based LSI WarpDrive, but keep in mind the IOMeter scores you saw earlier.  As queue depth scales, the Z-Drive R4 will pull ahead of other solutions rather quickly and by large margins.
Custom File Transfer Tests
Our next series of tests are what you might call more "crude measurements" in that we simply fired up our trusty stop-watch and clocked the time it took to complete a copy and paste command of a single large file or a bunch of large files from one storage volume in our test system to another.

** Please note that we utilized a Fusion-io ioXtreme card as our source drive in the following tests, to read files from or copy files to, for our read and write measurements. This affords us the luxury of much higher available bandwidth from the source drive or to a target drive, such that either direction would not be as much of a limiting factor in any given test condition.

Bulk File Transfer Tests - Read/Write Performance
Custom File Transfers Measured

As it demonstrated in our previous synthetic benchmarks, the Z-Drive R4 has a ton of bandwidth for large sequential transfers.  In these two test conditions, the Z-Drive R4 was able to edge out the next fastest SSD, OCZ's own RevoDrive 3 X2, in write performance but only matched it in read performance.

PCMark Vantage HDD
We like PCMark Vantage's HDD Performance module for its real-world application measurement approach to testing. PCMark Vantage offers a trace-based measurements of system response times under various scripted workloads of traditional client/desktop system operation. From simple Windows start-up performance to data streaming from a drive in a game engine and video editing with Windows Movie Maker, we feel more comfortable that these tests reasonably illustrate the performance profile of SSDs in an end-user/consumer or workstation PC usage model.

This series of Vantage tests will stress mostly read performance in pseudo real-world usage models, with a mix of sequential and random read transactions of both small and large file sizes.

Futuremark's PCMark Vantage

The OCZ Z-Drive R4 performs well in this first group of PCMark Vantage HDD tests, but it doesn't quite lead the pack as one might expect. It was only in the Windows Defender test that the Z-Drive takes the lead; in the other three tests the Z-Drive R4 trails at least one of its competitors and in two of the tests even the RevoDrive 3 X2 is faster.

PCMark Vantage HDD (Continued)

The following PCMark Vantage HDD tests are more write intensive and in some cases stress the Achilles' Heel of the average storage subsystem, that being random write performance.

Futuremark's PCMark Vantage

In the remainder of our PCMark Vantage benchmarks, the OCZ Z-Drive R4 takes the top spot in the Windows Media Center and Application Loading tests by relatively large margins, but in the Windows Movie Maker and Media Player tests, the Z-Drive R4 trails the RevoDrive 3 X2 and LSI WarpDrive.

Performance Summary and Conclusion
Performance Summary:
OCZ's Z-Drive R4 offered breakout performance in almost every test condition we put it under.  In fact, we were able to realize the card's max read/write bandwidth specification in our ATTO test and watched it flat out crush competitive products in our IOMeter tests.  Where this product won't shine so much is with light-duty end-user type usage models.  Stress the card with video production or other workstation-class workloads and you'll realize amazing throughput.  In a Datacenter environment, the Z-Drive could very well be the fastest server-class SSD out there right now and by a long shot, depending on application and workload.  One caveat however is that this card needs strong airflow over it, in its current design.  Inadequate airflow resulted in failures. Since we tested an early prototype card, we'll remain cautiously optimistic that OCZ will get a better handle on the thermal solution before they ship in production volume.


There are other factors to take into consideration with this new solution from OCZ as well.  The Z-Drive R4 is based on MLC NAND Flash, which doesn't have the write endurance of SLC NAND.  Many competitive enterprise class SSD solutions are built with SLC NAND for this very reason.  However, OCZ offers a solid 3 year warranty and a 2,000,000 hour MTBF specification, so you can formulate your expectations from there.  One thing that's for sure, is that solid state storage technology in general has made leaps and bounds in terms of reliability and life expectancy.  This is thanks in no small part to companies like SandForce with their excellent SSD controller technology and firmwares (employed on the Z-Drive R4) that minimizes inherent SSD write amplification issues.

That said, once again, OCZ continues to impress us with their PCI Express-based SSD solutions.  As technology analysts we like to temper our evaluations with a bit of skepticism and realism.  Are the performance numbers really that good?  Is that a consistent trend we're seeing or just an anomaly for one specific test or setup?  Is it really all that?  These are the questions we always challenge ourselves with, every time we take to the test bench with something new.  The long and short of our opinion of the new OCZ Z-Drive R4 is; holy, sweet mother of ridiculous bandwidth this thing is FAST.

In fact, the Z-Drive R4 is so fast, you better make good use of that performance when the product comes to market (should you decide to grab one) or some of us might come looking for you with a proverbial dope slap.  At $5 - $7 per GB (again, OCZ is still finalizing pricing), the Z-Drive R4 is not cheap.  It's about two times the price of OCZ's RevoDrive 3 product, though surprisingly those cards are almost at price parity with top-end SATA SSDs.  Fortunately, the Z-Drive R4 can prove to be over twice as fast as OCZ's RevoDrive 3 as well. And that's an impressive watermark to exceed, versus what is arguably one of the fastest PCIe SSD solutions on the market currently.

We're looking forward to just a few more refinements with OCZ's new Z-Drive before it ships.  Cooling challenges aside, OCZ has designed yet another ground-breaking SSD product with the Z-Drive R4.  It's the kind of product that should leave some of the big name players like Fusion-io, Micron and LSI rather uncomfortable. But when it comes to technology and continuous innovation, uncomfortable is a good thing.

  • Fastest PCIe SSD we've tested yet
  • 2.8GB/sec bandwidth, on paper and in benchmarks
  • Bootable device
  • SandForce SF-2200 maintenance, wear-leveling and endurance second to none
  • A fraction of the cost of competitive enterprise-class PCIe SSDs (per GB)but still expensive
  • Thermal sensitivity requires lots of direct airflow around the card

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