SanDisk is looking for a rise to prominence in the SSD segment with a new Marvell 88SS9187-based drive. The Extreme II packs 19 nm Toggle-mode NAND (from SanDisk, naturally), specialized firmware, and intriguing performance potential. How does it compare?
SanDisk hasn't really spent much time trying to break into the retail market. Its most notable effort was the original Ultra, a first-generation SandForce-based SSD. The drive didn't have much pep though, and it was up against fairly fast competition packing the formidable SF-2000 controller hardware.
Then again, companies like SanDisk don't really make their money selling drives online and through the odd brick-and-mortar outfit. Like Lite-On and Samsung, most of SanDisk's sales come from OEMs. Retail is usually a fraction of the overall pie, though it's acknowledged as an important piece of the whole. Making the move from selling drives in the OEM space to courting end-users directly isn't a walk in the park, either. Intel and Micron/Crucial started there to an extent, while companies like SanDisk and Toshiba are increasingly looking to play in the same sandbox.
You might not know this, but SanDisk and Toshiba collectively operate a joint venture under the aegis of Flash Forward. Intel and Micron have IMFT; SanDisk and Toshiba have Flash Forward. In essence, the two go halfsies on NAND fabrication. IMFT pumps out wafers of ONFi-capable memory, while Flash Forward makes Toggle-mode NAND. Samsung, the world's largest producer, keeps most of its flash for the company's own purposes, occasionally sharing it with special partners like Seagate. Intel/Micron and Toshiba will sell their production to almost anyone. But SanDisk, the biggest player in flash memory products for digital devices, holds on to what it gets for memory cards, thumb drives, and a range of proto-SSD storage products.
Speaking of SSDs, the first Ultra eventually gave way to a more potent SF-2281-based drive, the Extreme. SandForce's technology and Toggle-mode NAND have always been a powerful combination, but going the SandForce route isn't always advantageous for a company like SanDisk. Unfortunately, an inability to write its own firmware meant SanDisk's expertise in NAND manufacturing went to waste as it achieved similar performance as other SSD vendors. That partly explains the impetus behind recently-released products like the Ultra Plus, and the higher-end Extreme II we're looking at today.
Now, I know what you're thinking: naming something the Extreme II shows a distinct lack of imagination. Maybe so, but SanDisk's faster storage media for digital cameras shows up under the Extreme label. And regardless, we're far more concerned with what's under the hood.
The Extreme II ditches SandForce's hardware in favor of a Marvell flash processor (specifically, the Marvell 88SS9187). It's probably helpful to point out that SandForce's partners are locked into that company's firmware. Making major changes isn't in the cards, and there isn't a lot of available control over what the drive does or how it does it. Conversely, it's said that Marvell wouldn't write firmware for your fancy new SSD if you gave the company all the tea in China. Marvell's customers have to craft their own firmware. Stealing it might be a viable option. But in the end, we like the fact that each implementation is slightly different.
Writing the firmware probably isn't very hard. Making it truly outstanding is much more difficult. SanDisk adds another layer of complexity on top of its custom firmware package in an attempt to distinguish its drive from others based on the respected '9187. That layer is called nCache.
nCache isn't new, but it couldn't be implemented in previous SandForce-based SSDs without low-level firmware access. The Extreme II uses a variable-sized chunk of NAND operating in SLC mode to cache data for speeding-up low queue depth transactions, amongst other things (namely, caching small writes to commit to the MLC flash at a later time). It's difficult to say how large the cache is, but it's purported to be somewhere between 512 and 1024 MB.
According to SanDisk, the nCache system should generate a noticeable boost, especially with fewer outstanding commands in the queue (good news on the desktop, right?). It also helps rectify some of the shortcomings inherent to modern flash. As lithography shrinks and die capacity grows, page and block sizes increase as a consequence. Break down a trace of I/O activity and you'll find that most transfers are 4 KB in modern operating systems. Our Storage Bench trace is composed of a staggering 69.87% 4 KB transfers, and SanDisk believes that these smaller accesses are enhanced with a three-tier strategy: DDR3 DRAM, nCache caching, and MLC become its strategy to overcome the structural deficits of newer flash.
| SanDisk Extreme II | 120 GB | 240 GB | 480 GB |
|---|---|---|---|
| Controller | Marvell 88SS9187-BLD2 | ||
| NAND | 19 nm SanDisk eX2 ABL Toggle-mode, 64 Gb Die | ||
| Interface | SATA Revision 3.1 | ||
| Warranty | Five Year (Limited) | ||
| Seq. Read/Write MB/s | 550/340 MB/s | 550/510 MB/s | 540/500 MB/s |
| Random Read/Write IOPS | 91,000/74,000 IOPS | 95,000/78,000 IOPS | 95,000/75,000 IOPS |
| Die Count | 16 | 32 | 64 |
| MSRP | $130 | $240 | $430 |
There are three Extreme II capacity points: 120, 240, and 480 GB. And there are two different packages available per drive: a desktop kit with a 3.5" sled and mounting cable, and a laptop kit with a 2.5 mm shim for 9.5 mm Z-height applications.
Taking the Extreme II apart is easy. Four screws hide behind the label, and the plastic top half falls away from the metal chassis down below. A series of thermal pads mate PCB components to the metal housing for improved heat transfer. These pads cover the DRAM cache, Marvell's controller, and the eight NAND packages. It's like silly putty in a way; it tends to pull the screen printing off of component ICs, making them harder to decipher in photographs.
The 240 GB PCB you see here may not completely reflect the final product. What shouldn't change, however, are the eight quad-die packages of 19 nm ABL eX2 Toggle-mode NAND, adding up to 256 GB of capacity. The Toggle-mode interface eliminates the clock signal needed by synchronous flash, theoretically lowering power consumption. We've seen similar power characteristics from the 19 nm flash manufactured by Toshibaand SanDisk, though older Toggle-mode-based SSDs tended to use more power than competing drives with ONFi-compliant memory.
Marvell's '9187 controller is flanked by 256 MB of Hynix DDR3 DRAM. We like to see a ratio of DRAM to NAND running 1 MB for every gigabyte of flash on-board, so it makes sense that this 240 GB Extreme II has 256 GB riding shotgun. The 120 GB hosts 128 MB of cache, while the 480 GB model sports 512 MB.
The PCB's back side is bare, aside from some solder points.
Our consumer storage platform is based on Intel's Z77 platform controller hub paired with an Intel Core i5-2400 CPU. Intel's 6- and 7-series chipsets are virtually identical from a storage perspective. We're standardizing on older RST 10.6.1002 drivers for the foreseeable future.
| Test Hardware | |
|---|---|
| Processor | Intel Core i5-2400 (Sandy Bridge), 32 nm, 3.1 GHz, LGA 1155, 6 MB Shared L3, Turbo Boost Enabled |
| Motherboard | Gigabyte G1.Sniper M3 |
| Memory | G.Skill Ripjaws 8 GB (2 x 4 GB) DDR3-1866 @ DDR3-1333, 1.5 V |
| System Drive | Kingston HyperX 3K 240 GB, Firmware: 5.02 |
| Tested Drives | Sandisk Extreme II 120 GB, Firmware: R1311 |
| Sandisk Extreme II 240 GB, Firmware: R1311 | |
| Sandisk Extreme II 480 GB, Firmware: R1311 | |
| Comparative | OCZ Vertex 450 256 GB SATA 6Gb/s, Firmware: 1.0 |
| Seagate 600 SSD 240 GB SATA 6Gb/s, Firmware: B660 | |
| Intel SSD 525 30 GB mSATA 6Gb/s, Firmware: LLKi | |
| Intel SSD 525 60 GB mSATA 6Gb/s, Firmware: LLKi | |
| Intel SSD 525 120 GB mSATA 6Gb/s, Firmware: LLKi | |
| Intel SSD 525 180 GB mSATA 6Gb/s, Firmware: LLKi | |
| Intel SSD 525 240 GB mSATA 6Gb/s, Firmware: LLKi | |
| Intel SSD 335 240 GB SATA 6Gb/s, Firmware: 335s | |
| Intel SSD 510 250 GB SATA 6Gb/s, Firmware: PWG2 | |
| OCZ Vertex 3.20 240 GB SATA 6Gb/s, Firmware: 2.25 | |
| OCZ Vector 256 GB SATA 6Gb/s, Firmware: 2.0 | |
| Samsung 830 512 GB SATA 6Gb/s, Firmware: CXMO3B1Q | |
| Crucial m4 256 GB SATA 6Gb/s, Firmware: 000F | |
| Plextor M5 Pro 256 GB SATA 6Gb/s, Firmware: 1.02 | |
| Corsair Neutron GTX 240 GB SATA 6Gb/s, Firmware: M206 | |
| Graphics | MSI Cyclone GTX 460 1 GB |
| Power Supply | Seasonic X-650, 650 W 80 PLUS Gold |
| Chassis | Lian Li Pitstop |
| System Software and Drivers | |
| Operating System | Windows 7 x64 Ultimate |
| DirectX | DirectX 11 |
| Drivers | Graphics: Nvidia 314.07 RST: 10.6.1002 IMEI: 7.1.21.1124 |
| Benchmarks | |
|---|---|
| Tom's Hardware Storage Bench v1.0 | Trace-Based |
| Iometer 1.1.0 | # Workers = 1, 4 KB Random: LBA=16 GB, varying QDs, 128 KB Sequential, 8 GB LBA Precondition, Exponential QD Scaling |
| PCMark 7 | Secondary Storage Suite |
| PCMark Vantage | Storage Suite |
