SanDisk Extreme II 240 GB SSD Review

It has been a while since I have had the opportunity to review a SSD, and never have I reviewed a SanDisk SSD before. Normally SanDisk tends to play in the OEM arena including laptops and such, but since their Extreme SSD and now, what we have for review, the SanDisk Extreme II, they are broadening their horizons and continuing their drive in to the performance segment. We will dissect the drive and see how it does against some more, familiar to the performance market, drives.

Specifications

We will start out this section with the specifications of the drive straight from SanDisk. This line is offered in flavors from 120 GB to 480 GB and is built using SanDisk’s own 19 nm ex2 ABL MLC, Toggle NAND. As expected, it sits on a SATA3 (6 GB/s) interface. SanDisk is using a Marvell 88SS9187 controller (also found in Plextor M5 Pro/Extreme SSD) with their own firmware to drive it all. It seems like more and more SSD manufacturers are taking their firmware into their own hands, and usually this is a good thing! Not give anything away but I will tell you it’s a good thing in this case.

As far as performance goes, SanDisk shows 550/510 (sequential read/write) with 95K/78K IOPS. So you can see it’s up there with the best of them. This is nice to see out of SanDisk as usually their drives were OEM based without too much performance in mind (pre-Extreme series). Power consumption at maximum is a paltry 5 W when writing and 0.22 W at idle. They have a 2M hour Mean Time Before Failure (MTBF) and an 80 TB Write expectancy. 80 TB doesn’t seem like much, but this is a metric that I do not have anything else to compare to either. All this is supported by a strong five year warranty on the product, which is pretty significant as most drives are three years.

Some other high level features of this drive (from the SanDisk Technical Guide):

• ‚Launch applications faster and enjoy quicker system boot
  ups/shut downs
• Low power consumption for cooler operation and extended battery life
• Noise reduction for quiet drive operation
• Durable stainless-steel casing
• Available capacities: 120 GB, 240 GB and 480 GB
• Warranty: 5-year limited
• NCQ support up to queue depth = 32
• Advanced Flash Management (nChace, Dynamic and Static Wear-leveling, Bad Block Mgmt, Garbage Collection)
• Advanced Features (Tiered caching, Multi stream, Minimal write amplification)
• Support for Thermal throttling (performance throttled in case it breaches set temperature)

To get into more detail on the Advanced Flash Management, it is a feature implemented to improve random write performance. As a lot of us probably know, a modern OS deals with lots of small files with the majority being around 4k in size. That conflicts with the physical block structure for newer flash technologies. To help minimize that gap, SanDisk uses three ‘storage layers’:

1. Volatile cache (DDR DRAM cache)
2. nCache (non-volitile flash write cache)
3. Mass storage (MLC NAND flash)

The nChace is used to, “accumulate small writes (called segments) at high speed and then flush and consolidate them to larger MLC sections of the NAND Flash memory array.” As described below this is like a layer of SLC on top of the MLC to help keep your most common 4k files up to speed so to speak. Below is a diagram of their setup.

The SanDisk 240 GB SSD

Retail Packaging and Drive

In our first look at the packaging we see a pretty large box. I have to imagine this isn’t what you will be picking up off the shelves as it comes with its marketing goodies (tiny USB stick). Regardless, it is what I have in hand. You can’t quite tell the size in the first picture, but opening it up in the second reveals its size against the SSD in the box.

Next we see the drive close up, a typical 2.5″ SSD in black. The sticker on the front describes what it is, the SanDisk Extreme II Solid State Drive. Flipping it over reveals more information about the drive like its capacity (240 GB), Interface (SATA3), the voltage it runs off of (5 V), and of course the identifying serial numbers. We see mounting holes are available as expected and are on the side as well. What you don’t see here are screws to take this thing apart so I can show you the internals… where the heck did that go?

 Drive Internals

Ahh ha! They hid them underneath the sticker on the backside of the drive. Basically, you have no chance to open it up and then expect to return it. It will be incredibly obvious that it was messed with since you have to remove all four corners to get this apart. But, we don’t care about warranties here, so I opened this thing up with reckless abandon! Ok, that isn’t true, I was gentle.

So, inside we can see the Marvell controller, and some other IC’s which will be described a bit more below. What is new to me is to see thermal pads on all the IC’s. Normally it’s only on one item (the controller) and the NAND is left alone, but SanDisk has taken the liberty to put them on all of them. This helps keep the parts running cooler and uses its the aluminum chassis to assist with heat dissipation. This drive has thermal protection in it as well, so you should have a fair amount of headroom before that kicks in.

Below we can see the IC’s used. As mentioned above, the controller is the Marvell 88SS9187 using in house created firmware followed by the SanDisk NAND, and the Hynix cache IC.

Test Setup

The full test bed for this review is as follows:

There are several SSDs for comparison today; Kingson’s HyperX 3K 240 GB, Crucial’s M4 256 GB, Adata’s XPG SX900 128 GB , OCZ Vertex 4 256 GB (1.5 FW), and OCZ Vector.

Test Method

Before each test, the drive is Secure Erased (SE) to ensure optimal results. As you beat on a drive with benchmark after benchmark, performance can lower significantly until the drive runs its TRIM and GC functions… we don’t have the time to wait, so we SE the drive and it comes out factory fresh!

• Crystal Disk Mark – Run three times, Default settings
• AS SSD – Run at default settings
• ATTO – Run with default settings outside of the Queue depth of 10
• IoMeter 2010- Ran manually

Performance

Crystal Disk Mark

In this test we use the Random (default) testing to show us what the drives are all about. In this testing on my benchmarking PC, we see the Sequential Reads and Writes coming in at 490 MB/s and 500.3 MB/s respectively. For reads that puts it behind the formidable OCZ Vector, and HyperX 3K. Writes show the same placement, but the HyperX 3K drops off here so 2nd place is the Vertex 4. A good showing here.

For the 512K R/W’s the SanDisk puts up 420 MB/s in reads and 480 MB/s in writes, putting it again in the middle of the pack.

Moving on to 4k, the reads show this drive edging out the entire field, and falling to middle of the pack in the write test, just behind the Vector/Vertex 4 again.

Last up on this chart are the 4k QD32 tests coming in at 335 MB/s and 325.9 MB/s, reads and writes. Here again it falls slightly behind the Vector and Vertex4 by a small margin.

AS SSD

Here again we start with sequential reads and writes. The SanDisk offering hit 500 MB/s reads and 459.6 in writes, placing it 3rd in our comparison and a little behind the Vector and HyperX 3K. In the 4k reads we are seeing the Extreme II match the Vertex 4 at 30.6 MB /s, while the writes fall surprisingly to the lower end of this test. Moving on to the last section of this benchmark, the 4k 64Thrd, the SanDisk offering bounces back to tie the Vector for first place here, while being slightly behind it in the writes.

Next up in AS SSD are the Access Times. This metric tends to vary a bit so I don’t put too much stock in it. That said, a middle of the pack and 2nd place showing here… nice!

As far as the overall score of 1037, the drive sits squarely behind the Vector and Vertex 4, but miles ahead of the rest of the pack.

ATTO Disk Benchmark

For most (all?) companies that sell SSD’s, this is the benchmark that comes the closest to the SSD’s speed ratings. While it only shows a best case scenario with highly compressible data, it’s still a benchmark we want to use.

With the SanDisk offering, we can see the drive hitting its rated speed at the high end, and even a bit more, so that is good. Checking out the lower end of things, where the drives will differ, we see the Extreme II beating out the competition from 16k on down, even besting the Vector in 4k reads! This drive seems to love those 4k reads!

For the writes portion, we see the same behavior in the large segments, eclipsing its rated numbers. However, when we move down to writes, the story looks remarkably similar to the results in other applications with the SanDisk Extreme II falling just behind the Vector and Vertex 4 in 4k writes and beating out the rest of the field quite easily.

IOMeter

Last up in our benchmarks is IOMeter. Here we run each of these set manually instead of any .icf files or the included profiles. The SanDisk Extreme II managed to come in second here with the 2MB Writes and Reads at 515 MB/s and 539 MB/s respectively, only losing out to the Vector.

For the 4k writes and reads, we find another similar story in that it performs quite well but just a bit behind the OCZ SSDs.

Final Thoughts & Conclusion

I have to admit coming in to this review I had my doubts about the performance of this drive for some reason, but I can safely say it proved me wrong. While it wasn’t class leading, it was certainly in their ballpark across the board. That brings me to the next talking point, pricing. This drive at Newegg.com is $229.99 which puts it well below the Vector and Vertex 4 ($40/$30 less respectively) and $10 below the, not included in this testing but similar performing to all here, the Samsung 840 Pro 256 GB. So the unit is priced well  for its performance and capacity among its peers.

So to wrap this all up, we have a very fast drive sporting a five year warranty with a price point that is spot on in today’s SSD landscape. The SanDisk Extreme II should be one of the top choices on your list for high performance SSDs. As you all expected after reading the conclusion, this product is Overclockers.com approved!

– Joe Shields (Earthdog)