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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  • Hulk - Monday, May 07, 2007 - link

    Since Flash memory is so cheap how come some manufacturer can't make a hard drive unit where you can plug in identical memory cards? You can get 4GB modules for less than $40 these days. 8x40=$320 for 32GB. Using a Raid type parallel access scheme you should be able to get 8 times the performance of one module. So if one module can write at 6MB/sec then 6x8=48MB/sec.

    Plus if a module starts to fail you could replace it.

    These are just questions from someone that only has a basic understanding of this technology of course. If it could work I'm sure someone would be doing it. I'm curious as to the specifics of why this idea would not be feasible.
    Reply
  • PandaBear - Thursday, May 10, 2007 - link

    Because the cheap nand doesn't last 100k (MLC) and they are slow. Example:

    Sandisk CF cost around $10/gb and is around 10MB/S if trimmed to high performance (Ultra II), and 20MB/S if running parallel internally (Extreme III)

    The same CF capacity will cost 1.5x to make it 40MB/S in parallel but gives you very high reliability (250k to 1M write/erase).


    So there you have it, for HD you better play it save and use expensive nand, and it won't cost $10/GB
    Reply
  • miahallen - Wednesday, May 09, 2007 - link

    One of these:
    http://www.newegg.com/Product/Product.aspx?Item=N8...">http://www.newegg.com/Product/Product.aspx?Item=N8...

    Four of these:
    http://www.newegg.com/Product/Product.aspx?Item=N8...">http://www.newegg.com/Product/Product.aspx?Item=N8...

    And, four of these:
    http://www.newegg.com/Product/Product.aspx?Item=N8...">http://www.newegg.com/Product/Product.aspx?Item=N8...

    $340 total for 32GB - In a RAID0 that would be rated speed of 80MB/s read, 72MB/s write, and still great random access speeds.
    Reply
  • Ajax9000 - Monday, May 07, 2007 - link

    There are CF2IDE and CF2SATA adapters (e.g. see this list http://www.addonics.com/products/flash_memory_read...">http://www.addonics.com/products/flash_memory_read... ).

    For about the same price as the SuperTalent 16GB SSD you could build a 32GB IDE SSD using two 16GB CF cards and a dual slot CF2IDE adapter.
    BTW, DansData looked at this sort of thing back in 2000 (http://www.dansdata.com/cfide.htm">http://www.dansdata.com/cfide.htm ) and earlier this year (http://www.dansdata.com/flashswap.htm">http://www.dansdata.com/flashswap.htm ) but didn't go into performance details.

    I think it would be very interesting if Anandtechs' upcoming review of consumer oriented SSD products also looked at CF2IDE and CF2SATA adapters as an interim solution untill "proper" SSDs get somewhat cheaper.

    Are there issues with this? Of course, but they may be reasonable tradeoffs.

    IDE vs SATA
    The SuperTalent review notes that SSDs tend not to be interface bound at the moment so there may not be much difference between SATA and IDE for SSDs. Also, as CF uses an IDE interface (and I understand that the CF2IDE adapters are little more than physical connects) using a CF2IDE adaptor shouldn't impact on performance either ... as long as the I/O controller in the CF card is good (and there are 133x and 150x CF cards in 12 & 16 gig)

    Wearout
    Reflex's comments are a fairly typical concern with respect to the use of flash memory in consumer PCs. And if there was no wear-levelling or ECC on consumer CF cards they simply couldn't be used for swap files etc. BUT someone has commented on DailyTech that that flash cards commonly have memory controllers which do wear levelling and/or ECC (http://www.dailytech.com/article.aspx?newsid=7135&...">http://www.dailytech.com/article.aspx?n...&com... ). Even so, it would seem dangerous to have the OS and swap on the same card.

    The thing I like about the double CF2IDE adaptor (and what I'd like to see someone such as AnadTech test out :-) is the possibility of having swap on a smaller/cheaper card (say 4GB?), so NAND wearout of the swap can be contained to a more affordably replaced item.

    In summary compare the price and performance of a dual-CF2IDE adapter + 12/16GB CF (OS+apps) + 4/8GB CF (swap) against a 16/32GB SSD.

    Adrian
    Reply
  • Reflex - Tuesday, May 08, 2007 - link

    Just to make something clear: Wear leveling is not a magic pancea. The ratings they give are taking wear leveling into account. It is not "100K writes + wear leveling to stretch it further" its "100k writes due to our wear leveling technique". Even without a swap file, for a typical workstation you would use that up fairly rapidly. I am going to go out on a limb though and guess that they probably have more like 250-500k writes, but are only guaranteeing it for 100k to protect themselves. For the market these are designed for, 100k writes is more than the machines will likely use in their service lifetime. For a desktop PC, however, it would wear out very very quickly as I have stated above. Reply
  • Ajax9000 - Tuesday, May 08, 2007 - link

    Thanks Reflex.

    I'm still curious re the performance comparison, as well as the TCO/longevity issue. :-)
    Reply
  • yyrkoon - Monday, May 07, 2007 - link

    Just a guess, but I think it would be a nightmare desiging a controller that could address mutliple 'Flash Drives'. Lets take your typical SD card for example, whatever it plugs into has one controller for the card, and if what you're saying were to happen, you would need multiple controllers, all talking to a main controller, which then in turn would communicate with the actual HDD controller. This would be slow, and problematic, especially when data spanned one or more memory media device. I am not saying it could not be done, and may even possibly done well, but there are other factor such as liscencing fees, and controller costs, etc.

    As an example, do you have any idea what it takes to get your hands on a legitimit copy of the SATA specification ? Last I looked, its ~$500 for the design specifications 'book', and every device you make that uses the technology requires a liscencing fee. In other words, it is not cheap, I would imagine the same applies for SD controllers (or whatever form of media said OEM would choose/support), and one normally goes into business to make money, and this would likely eat deeply into the pockets of the share holders.

    I can think of more reasons, and the ones given may not be entirerly accurate, but this should give you some idea as to 'why'.
    Reply
  • JoshuaBuss - Monday, May 07, 2007 - link

    I would love to know the exact same thing. You can buy 4gb SD cards for $40.. 2gb for $20 if you shop around. Flash memory seems to be practically given away these days.. it's so friggin cheap. Reply
  • Lonyo - Monday, May 07, 2007 - link

    I think they are doing it. IIRC there was something posted on DailyTech about a card which used regular memory cards and hooked up to a SATA/PATA interface. I think anyway, not 100% sure. Reply
  • yacoub - Monday, May 07, 2007 - link

    well i guess they gotta start somewhere :D Reply

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