Sandisk Extreme II 240GB Solid State Drive Review

by - 6 years ago



The SSD market as many people know it is inundated with drives that have one of LSI’s SandForce SF-2281 controllers at their heart and whilst this is not a bad thing – given that they have proven reliability and some of the best performance to be had, they are not without their faults.

SSD owners today, use their drives for a multitude of tasks and breaking these tasks down to the way the drives see the data, we have two data types; compressible and incompressible. SandForce based drives typically use lossless data compression to minimise the write cycles to the flash in order to prolong its life span, however not all data sets can be compressed in this way and consequently when these controllers meet this type of data, the write speeds consequently slow down as the data takes more time to process.

SanDisk’s Extreme series of drives as we have here today, are now on to their second generation and following the success of the original Extreme that was based around the SF-2281 controller, SanDisk want to take the performance up a notch to give this drive a huge selling point against every other drive out there. To do this, the SandForce controller had to be laid to rest as the way it handles incompressible data was not going to be right for an ‘extreme’ drive. As a result, Marvell has been brought in with its top end controller and this teamed with SanDisk’s own 19nm Toggle NAND MLC flash and a 256MB cache is what is set to give this drive the grunt it needs to push it to the top of the SSD performance charts.


A Closer Look

Like so many other SSDs to come to market in recent months, the Extreme II follows the 7mm profile, making it ideal for ultrabooks alike. Sandisk do offer this drive in two retail options, either with a shim to convert the drive to a 9mm profile or a desktop mounting kit for a 3.5″ drive bay.

On the rear of the drive, a large sticker covers the four screws that hold the drive together and is also the warranty label as well.

Taking the case apart, the first thing that I note, apart from the very lightweight build is the large number of heat pads that SanDisk have used on every major component within the drive. These heatpads are there purely to aid in the cool operation of the drive as heat within storage drives can have a major impact on the drives heath in the long run.

Case aside and looking a little closer at the PCB itself, the Extreme II sees a totally remodelled PCB design due to the use of a Marvell controller as opposed to a SandForce controller that we have seen in the past. The upper side of the board is host to the controller, DRAM and eight NAND ICs which I’ll look more closely below.

The rear of the 240GB PCB is rather more plain with no major components to be found on this model. On the 480GB model, this area is likely to be used for further flash storage.

At the heart of the SSD lies one of Marvell’s 88SS9187-BLD2 ‘Monet’ controllers. This controller has taken place over the SandForce SF-2281 controller that we saw on the previous generation of Extreme SSDs.

Below the Marvell controller is a Samsung branded K4B2G1645E-BEK0 DRAM IC, which gives the drive 256MB of DDR3 1066MHz storage cache enabling the drive to run at faster speeds.

The flash itself is some of SanDisk.s own 19nm Toggle Mode MLC NAND. Each of the eight modules that are to be found on this particular board have a capacity of 32GB, which added up gives the drive a total storage capacity of 256GB. Due to the over provisioning that SanDisk have given the drive to reduce the performance degrade as the drive fills up, the advertised speed is 240GB which is commonly seen among SSDs.


Test Procedure

Test system:

  • Asus Maximus V Formula
  • Intel Core i7 3770k
  • Corsair Vengeance 1866MHz 16GB
  • XFX Radeon HD 7970
  • Corsair H100i
  • Corsair HX1050W
  • Kingston HyperX 240GB SSD
  • AOC E2795VH

We would like to thank AOC, Corsair, Kingston and Lian Li for supplying us with our test system components.

Many different software applications are also used to gain the broadest spectrum of results, which allows for the fairest testing possible.

Software used:

  • AS SSD
  • ATTO
  • CrystalDiskMark
  • Anvil’s Storage Utilities RC6
  • IOMeter


The AS SSD software determines the performance of Solid State Drives (SSD). The tool contains five synthetic and three practice tests. The synthetic tests determine the sequential and random read and write performance of the SSD. These tests are performed without using the operating system caches. In Sequential tests the program measures the time it takes to read and write a 1GB file respectively.

Straight out of the box, the Extreme II comes up trumps with a strong set of results with the Marvell controller with speeds topping out at well over 120MB/s for the 4K write tests.



The ATTO Disk Benchmark performance measurement tool is compatible with Microsoft Windows. Measure your storage systems performance with various transfer sizes and test lengths for reads and writes. Several options are available to customize your performance measurement including queue depth, overlapped I/O and even a comparison mode with the option to run continuously. Use ATTO Disk Benchmark to test any manufacturers RAID controllers, storage controllers, host adapters, hard drives and SSD drives and notice that ATTO products will consistently provide the highest level of performance to your storage.

The underlying performance that hte Extreme II and its Marvell controller is able to give is surprisingly high with both read and write speeds surpassing 520MB/s at 1024k.



CrystalDiskMark is a small HDD benchmark utility for your hard drive that enables you to rapidly measure sequential and random read/write speeds.

Here are some key features of “CrystalDiskMark”:

  • Sequential reads/writes
  • Random 4KB/512KB reads/writes
  • Text copy
  • Change dialog design
  • internationalization (i18n)

Like AS SSD, the 4k results in CrystalDiskMark are very strong and with a QD32, the speeds are nearly 10x as fast on the read and 3x on the write.


Anvil’s Storage Utilities is a new benchmarking utility that we have started using here at eTeknix, it’s completely free to download and has the ability to test mainly hard drives and solid state drives, but also any other form of storage medium that you can throw at it. As well as testing the drive in a variety of benchmarking tests, it also has a drive endurance test that consistently reads and writes data to the selected medium to give days, months and potentially even years of use in a shorter period of time to see how the drive copes in the longer term.

As we can see from the IOPS, the Extreme II has similarly high levels of performance on both the read and write side of the table with results just pushing 80k IOPS.

As we can see, unlike SandForce based drives which do suffer from a bit of performance loss with incompressible data, the Marvell controller is able to give as good as it gets – no matter what the compression level.



IOMeter is an I/O subsystem measurement and characterization tool for single and clustered systems. It is used as a benchmark and troubleshooting tool and is easily configured to replicate the behaviour of many popular applications. One commonly quoted measurement provided by the tool is IOPS.

IOMeter allows the configuration of disk parameters such as the ‘Maximum Disk Size’, ‘Starting Disk Sector’ and ‘# of Outstanding I/Os’. This allows a user to configure a test file upon which the ‘Access Specifications’ configure the I/O types to the file. Configurable items within the Access Specifications are:

  • Transfer Request Size
  • Percent Random/Sequential distribution.
  • Percent Read/Write Distribution
  • Aligned I/O’s.
  • Reply Size
  • TCP/IP status
  • Burstiness.

Looking more precisely at the read IOPs with Iometer, after a 15 minute test run, the drive is able to give well over 90,000 IOPs making it one of the best drives we have seen.

The write IOPS as expected are a little lower, however they are still relatively high with 70,000 IOPs recorded.


Final Thoughts

For many people, looking for a new SSD generally results in a SandForce powered drive being purchased due to the fact that the large majority of drives on the market have one of these very successful LSI made controllers at their heart. As with all things though, there is always going to be a set of pros and cons. On of the downsides for SandForce is its overall ability to handle incompressible data over compressible data. Typically we see this as a drop in the read and write speeds, but with the Extreme II using on of Marvell’s top end controllers and the same style of caching that we saw on the Ultra Plus drive not too long ago, the speeds right across the board are top end.

When its ground down to raw performance on the whole, the Sandisk Extreme II is one of the fastest drives on the market right now. This is a huge selling point for Sandisk and with the SSD market becoming more and more fierce and the number of competitors growing, being able to claim rights to the top such as this are hard come by. Given how far SSD performance has come on over the last few years, I can only but begin to wonder what the next step will be for a single drive. Granted there is always the option of RAID0 and with drives becoming more and more reliable in the long run whilst coming down in cost, it does make sense to some to do just that.

Mentioning cost, this is truth be told, the breaking point for the sale of most drives. The drive could be the fastest on the market, from a reputable brand with the right capacity, but if the price tag is not quite right, then sales are likely to suffer in the long run. Remarkably, given the above facts, the 240GB SKU of the Extreme II comes with a price tag of nigh on £150, working out at 62.5p/GB which is well below the £1/GB margin that we look for in any drive.

Overall I’m not just happy with this drive, I’m very impressed, I know that Sandisk do have what it takes to make top end drives, but i was never honestly speaking something that was going to perform this well right across the board, but this is just what I’ve been given.


  • Well known vendor
  • Handles compressible and incompressible data just as well as each other.
  • Fast read and write speeds
  • ~95k read IOPs and ~78k write
  • Amazing value for money


  • Controller not as well known as SandForce

 “The Extreme II line of drives from Sandisk are some of the best drives on the market today and should be a definite contender for the short list of parts on any new system build or even for an upgrade.”

Sandisk Extreme II 240GB SSD Review

Thank you to SanDisk for providing this review sample.

Article Index

  1. Introduction
  2. A Closer Look
  3. Test Procedure
  4. AS SSD
  5. ATTO
  6. CrystalDiskMark
  7. Anvil's Storage Utilities
  8. IOMeter
  9. Final Thoughts
  10. View All

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