We recently reviewed a 1TB drive from Hitachi and started reminiscing about the progress of hard drives. It has been a little over fifty years since IBM introduced the first hard drive in September of 1956. This hard drive had a 5 megabyte storage capability and consisted of 50 24-inch platters in an enclosure that required a fork lift to move it. The drive was only available at the time with the IBM 305 RAMAC system that was designed to process accounting information.

The advances in storage technology have been fast and furious since that eventful day in 1956. Over time hard disk capacity has grown increasingly larger while at the same time the drives have become smaller, less expensive, and generally a lot more reliable. However, the technology we have become dependent upon for our storage requirements has not really changed at all. We still have the basic design where a platter coated with a ferromagnetic material is used to store data and spins at a constant rate with an actuator arm hovering right above it which contains a read/write head for data retrieval or creation.

This mechanical process of storing and retrieving data has transformed over the years into what can only be considered a technical marvel but this whole design is still prone to disaster. After all, at any given time the read/write head could fail or physical shock could occur that would send it crashing onto the platters taking valuable data with it. This is only one of many scenarios that could cause data loss and the basic nature of the hard drive being a mechanical device still has inherent disadvantages that range from heat and power consumption to noise levels that are obtrusive at times. While we are at the point of another design technology breakthrough that will once again improve capacities and speed, the hard drive is still and will always remain a mechanical device.


There is always a better mouse trap and today we will take a quick look at one alternative to the ubiquitous hard drive. This particular mouse trap goes by the name Solid State Drive. A solid state drive is based on flash memory along with a flash controller and management software. The first flash memory was invented in the Toshiba laboratories and became a commercial product four years later in 1988 when Intel introduced it into retail markets.

Solid state drives have been around since 1989 but have been limited to highly specialized markets such as medical, industrial, or military use due to the exorbitant costs involved since their introduction. In fact, at one time a 1MB drive cost around $3500 and performed significantly worse than its mechanical counterpart. However, the drives thrived in the military, aerospace, and to some degree the medical fields due to the advantages of a flash memory based drive. Since these drives do not contain any moving parts they consume significantly less power, generate minimal heat, are totally silent, and as flash memory and controllers have matured they now offer similar or better performance when compared to hard drives in certain usage scenarios.

When we look at the market today, we see an explosive growth in the use of flash memory in everything from cell phones to iPods. As the volume of flash memory has grown over the past few years, the price has gone down. As of late, the price of flash memory has been declining about 40% per year on average. Along with the price decreases we have seen an exponential increase in the capacity of flash memory while its packaging footprint has been greatly reduced. In fact, the etching process has now reached a 50 nm design compared to 90 nm just two years ago. Also, the widespread use of multi-level cell (MLC - 2 bits per cell) NAND instead of the faster but significantly more expensive single-level cell (SLC - 1 bit per cell) NAND has helped reduce costs.

While the size and memory capacities are now competitive (128GB in a 1.8" form factor), the pricing is still significantly higher when compared to hard drive designs. The average cost for a competitive SSD design in the consumer market is currently about $17 per GB of storage. This does not compare favorably to $0.25-$0.40 per GB for a typical hard drive today. However, we are at the point where a SSD product can be competitive with a hard disk in the consumer market based upon its advantages to cost ratio in applications like a rugged notebook or ultra-light design that requires extremely low power envelopes and shock resistant operation. It's worth remembering that not long ago the first GB hard drives could easily cost several hundred dollars.

We are also at the point where the flash controller and software can ensure the longevity of the drive but more importantly that data integrity is significantly better than a typical hard drive. Current SSD products being released can ensure at least 100,000 write/erase cycles per sector which equates to a 1,000,000 hour MTBF rating. This means an average user can expect to use the drive for about 10 years under normal usage conditions or around five years in a 100% power-on state with an active/idle duty cycle at 90%. These numbers are subject to change depending upon the data management software algorithms and actual user patterns.

Manufacturers have started providing consumer level solid state drives with 67MB/sec read speeds and 45MB/sec write speeds along with a random read rate of 7000 inputs/outputs per second (IOPS) for a 512-byte transfer - more than 100 times faster than a hard disk drive. While the IOPS rate is impressive and certainly contributes to real performance increases by removing certain I/O bottlenecks, we found the average random access rate of .12ms to be an even bigger factor in providing class leading performance in several cases.

Our technology preview today is based on the Super Talent SSD16GB25/25M Flash Drive that is being introduced into the commercial and industrial markets at this time. This drive has lower performance capabilities than the recently released consumer drives from SanDisk and Samsung but will provide us with an early peek at SSD performance in several areas. We will state upfront that our results and comparisons against two top performing hard drives should be tempered greatly as this drive is targeted to a different market sector.

We are currently testing consumer oriented SSD products and will provide a full review in the near future with a revised benchmark test suite designed around Windows Vista and suitable for providing direct comparisons to the new hybrid hard drives that combine NAND flash memory and a mechanical hard drive to offer the best of both worlds, or so we think. In the meantime, let's see the specifics on this drive.

SSD16GB25/25M Features
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  • Samus - Monday, May 07, 2007 - link

    Simply awesome, thanks for the review Gary. This is exciting technology for sure. Only took them 20 years to make it cost effective and reasonably good storage. Reply
  • redbone75 - Monday, May 07, 2007 - link

    I would say SSD's have a few more years to go before they become cost effective, in the home consumer market, anyway. That market will be very small until the price/GB becomes more reasonable. Reply
  • Lonyo - Monday, May 07, 2007 - link

    Is there any chance for comparison of some 1.8" drives in the future?
    Since 1.8" mechanical drives are somewhat slower than 2.5 or 3.5" mechanical drives, and 1.8" laptops are looking at things like low power consumption, it would be nice to see, assuming you can get hold of some 1.8" drives of both types.
    Reply
  • Reflex - Monday, May 07, 2007 - link

    These drives are great in an embedded or manufacturing environment. Typically they are not written to frequently so you will never hit the write limitations. As a desktop PC drive however that write limitation could be hit very quickly, within a year even. Furthermore, having worked with these drives extensively in embedded environments, I will point out that when the write limitation is hit, you can no longer read the device either. Since there is no real warning, you simply suddenly lose access to all data on that drive.

    Solid state storage is the future, but not in the form of today's flash. The write limitation is severe, and very problematic. There are competing technologies that hopefully will show up sooner rather than later.
    Reply
  • falc0ne - Monday, May 07, 2007 - link

    "The SSD16GB25/25M features a read seek time of less than 1ms, a maximum read/write speed of up to 28 MB/sec, a sustained transfer rate of 25 MB/sec, and an estimated write/erase cycle of approximately 100,000 cycles. This equates into a 1,000,000 hour MTBF rating and indicates a 10 year life expectancy based upon normal usage patterns. Super Talent has developed a set of proprietary wear leveling algorithms along with built in EDD/EDC functions to ensure excellent data integrity over the course of the drive's lifespan."
    This passage tells a completely different story..
    Reply
  • mongo lloyd - Monday, May 07, 2007 - link

    Dan at Dansdata.com has said the exact same things as Reflex here for quite a while, and I tend to believe him more than SuperTalent's PR department.

    Also, as Reflex points out, NAND flash has usually way more than 100,000 write/erase cycles. 1 million cycle is not too uncommon.

    Regular CompactFlash memory (previously NOR flash, nowadays NAND flash) can take up to the same order of magnitude of write/erase cycles, and we all know memory cards for digital cameras have quite a finite life. And that's without putting a paging file on them.
    Reply
  • PandaBear - Thursday, May 10, 2007 - link

    It depends on what kind of Nand. MLC usually can barely hit 100k for good ones (i.e. Toshiba and SanDisk) while 5k for bad ones (i.e. some batch of Samsung that got rejected and they have to dump in the spot market).

    For a camera, you will have to wear out your camera's shutter before you can wear out the card, but for HD, you better have very good wear leveling and good nand before even attempting).
    Reply
  • Gary Key - Monday, May 07, 2007 - link

    The manufacturer's are taking a conservative path with the write/erase cycles per sector and it has been difficult to nail them down on it. The latest information I have from SanDisk as an example is that the non-recoverable error rate is 1 error per 10 to the 20th bits read on their current drives but they have not committed to active duty cycles or power-on hours in arriving at that calculation. The majority of the SSD suppliers are focused on MTBF ratings at this time. We will have further details in our consumer article as I expect Samsung to open up on the subject. Reply
  • PandaBear - Thursday, May 10, 2007 - link

    Nand don't wear out by sitting around, they wear out by erase/program permanently or read disturb (recoverable just by a rewrite). So MTBF is meaningless. You have to do a lot of reading continuously in order to wear out by read. Actually there are algorithms that protect such cases already by refreshing it, so no harm is done.

    It is the write that really kills the sector, and Samsung did not mention its erase/program for a reason: they failed their own spec that many reputable clients rejected their order (i.e Sandisk rejected their order from Samsung MLC, and Apple uses excessive recovery algorithm to tolerate them on the audio playback, those Taiwanese cheap flash that you get for free with super slow performance or die after 2 weeks, well, you know what you will get when you open up the case).

    For their SSD, they may use SLC instead for the performance and reliability reason. It costs 20% more in spot market, but manufacturing cost is much higher (almost 2x when you think about it), so it will cost more.

    Reply
  • Reflex - Monday, May 07, 2007 - link

    First off, 100,000 is a VERY VERY low write rating for flash, typical drives nowadays have 250k+ write cycles.

    Secondly, as pointed out by the article, the intended market is industrial and embedded, which as I stated originally, is an environment where the drives are rarely written to. Typically you have a bootable image in those environments, and it is write protected in some fashion, or requires a very small number of writes.

    And finally, if you think 100k write cycles is a lot, watch the drive light on the front of your PC someday. Every flash is a minimum of one write or read operation. Calculate how many times that flashes in ten minutes of 'typical' use. Then extrapolate. You'll understand what I mean.
    Reply

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