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The OS and application data are continually becoming easier to fit on today's platters - why not move it to NAND? - Image courtesy Samsung
Do you need a solid-state drive? Samsung says you do, and here's why

DailyTech recently had the opportunity to sit down with Don Barnetson, Samsung's director of flash marketing, to chat about the future of NAND devices.  Specifically, we picked Barnetson's brain about solid-state drives and future NAND storage.

Over the past few months, we've seen dozens of announcements about solid-state hard drives.  PQI has already announced a 64GB flash drive (which coincidentally, is based on Samsung NAND), which ASUS, Fujitsu, Samsung and Sandisk have all announced products based on solid-state hard drives. Given the fact that the hard drive has been the bottleneck on PC performance for years, the question has to be asked is solid-state technology ready to take us out of the dark ages of storage? 

In the 90s, the largest advocate of more storage was Microsoft.  The company insisted we have larger hard drives for Windows 95, then Windows 98.  Then the next largest proponent for more storage became the application designers, pleading users to get larger hard drives for image manipulation or games.  But today, I can fit Vista, Outlook (and all of those 2GB PST files) and even a few games in less than 1/10th of my 250GB hard drive.  The other 100-odd gigabytes is mainly composed of MP3s and a few DVD rips.  I am the prime candidate for a solid-state hard drive.

Most business users claim only a fraction of the hard drive space provided for them, especially considering most unique data gets written to a network anyway.  The operating system and applications can all fit in less than 10GB of space, which is well within the sizes of solid-state hard drives today.  Barnetson's group has calculated that during an 8-hour day the average hard drive:
  • Has about a 1% chance of failure per year
  • Consumes 9W
  • Loses about 7 to 15 minutes per day in productivity
The fact that we lose so much time alone due to hard drive spin-ups and seeks is alone appalling, but the decreased power consumption is what is driving solid-state adoption today. A NAND device uses less than 200 milliwatts during read/writes, and 0 watts when not being accessed.  On the desktop this is relatively unimportant, but on a notebook the hard drive accounts for 10% of the total power draw.  Cutting this number down to less than 1% means an extra 12 minutes of usage on my 2 hour battery.

When asked about the reliability of NAND-based hard drives, Barnetson had no problem shrugging off fears of write corruption of failure.  "Samsung's solid-state devices have a MTBF of approximately 1 to 2 million hours."  Typical disk-based hard drives have a mean-time between failures of approximately 100,000 to 200,000 hours.  Since there are no moving parts, the only real point of failure is for something to come unsoldered or a problem with the physical bit during a write.

Obviously, write-errors are a huge concern for those who have used flash products in the past.  Only a few years ago the highest-end flash media was only useable for 1,000 or so writes.  At that point the physical bits would "burnout" and could no longer be flipped. Today's single-level cell (SLC, memory that stores one bit per cell) is rated in excess of 100,000 writes before burnout.  Multi-level cell flash, memory that stores multiple bits per cell, is significantly cheaper but even then is still rated at over 10,000 writes before burnout. 

Is 10,000 writes enough?  Absolutely, assures Barnetson.  Samsung memory uses a technique called "wear leveling" to distribute the writes on a media through as many groups of cells as possible. The idea behind wear leveling is that all of the cells have approximately the same amount of writes to them, maximizing the life of the device.  Consider a typical computer that writes 120 megabytes per hour to the hard drive.  On a 32GB solid-state NAND drive, wear leveling would distribute this data over the entire drive -- it would take 267 hours to fill the device once. Even on a multi-cell flash device, at this rate it would take no less than 150 years to burnout all the bits on the SSD.  Single-cell drives are capable of ten times as many writes.

Even so, Samsung's initial solid-state drives are all single-cell designs.  This first generation of SSDs are prohibitively expensive for most, but Samsung's SSD roadmap already has plans for multi-cell level drives as early as next year, which should bring the cost down considerably.  Additionally, Samsung anticipates announcing drives in capacities of up to 128GB in early 2008. 

Solid-state memory will not entirely replace disk drives.  The fact is, media is more and more prevalent each day.  5 years ago, a fringe enthusiast may have had as much as 1GB of MP3s on his hard drive.  Today even the average user may have 100GB of just Lost episodes on their hard drive.  As an intermediate step hybrid hard drive, hard drives with multi-gigabyte NAND caches, will provide the 2007 stopgap before really big SSDs get cheap.  These drives can load the entire operating system, some applications and even a little bit of user data (like Outlook PST files) onto the NAND.

Our insatiable appetite for media cannot be even remotely matched with the production of NAND memory right now, but for games and operating systems, solid-state devices are here and ready to go.

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RE: Let me be the first ..
By Aeros on 11/15/2006 6:22:31 PM , Rating: 2
My only concern is I/O speeds... Any mention of improvments in that area?

RE: Let me be the first ..
By Fnoob on 11/15/2006 7:02:05 PM , Rating: 1
That was my concern as well. I work in digital imaging solutions, and I have yet to see a flash memory card of any flavor that comes close to even a decent 7200RPM IDE drive. With even SCSI320 15,000RPM drives still being a bottleneck in todays systems, I don't see flash drives replacing HDD's for a long while to come.

RE: Let me be the first ..
By ydgmdlu on 11/16/2006 12:34:20 AM , Rating: 3
Actually, flash memory is significantly faster than magnetic memory (i.e. current HDDs). The limitations that you're experiencing are due to the interface with the memory, not the memory in itself.

RE: Let me be the first ..
By GoatMonkey on 11/16/2006 8:57:11 AM , Rating: 4
It should be obvious that a solid state drive can be made to perform much better than any traditional hard drive. You're expecting the performance to be the same as what you get from your SD memory card or thumb drive. This is not the same thing.

Think more along the lines of the Gigabyte RAM Drive that was released a while back. That's not exactly the same either, since it's using regular RAM with a battery backup, but that type of drive is capable of filling up the entire SATA bandwidth, while a regular hard drive can't come close to that.

Of course, I have no information about the actual performance of these Samsung drives, but you can bet that they won't be slower than a regular hard drive, it would just defeat the purpose.

RE: Let me be the first ..
By caater on 11/15/2006 8:26:30 PM , Rating: 3
THG reviewed this samsung SSD a few months ago here -
it has ata/66 interface and in tests was limited to interface only.
but even that 50MB/s all through the "disc" is very impressive.
and i can't see no reason why they wouldn't produce a unit, only limited by SATA or even SATA-II interface.

RE: Let me be the first ..
By mindless1 on 11/24/2006 3:34:44 AM , Rating: 2
False. ATA66 max realized throughput is higher than 50MB/s. That is a device (SSD) limitation, not the interface.

The reason why they wouldn't is fairly easy to see. There's no new technology here to have a SSD. It's only a matter of packaging, to take an existing CF3.0 class controller, put this all on a larger card in a plastic shell with IDE spaced pinout.

To go with SATA or SATA-II, they will have minimal to no benefit, would have to develop a new controller. It's already obscenely expensive as it is- there is no real justification for these to cost more per GB than a CF card, particularly buying so many GB at a time from a memory manufacturer.

RE: Let me be the first ..
By leidegre on 11/16/2006 3:21:20 AM , Rating: 2
I've been using a kinda odd setup in my computer were I have a RAID0 + 320GB (with 16MB cache). i usually run the OS and perfomance applications such as games of the RAID0 and that has proven to be very efficent.

Still this Solid-State stuff looks intresting, becuase that would not only save power, but it could be a perfomance device as well. There are some enterprise server storage solution based of SSD, and they calim that they out-perfom any other solution by years. And if that is true, which i do not doubt, then SSD will certainly be able to ramp up perfomance I/O. Also, harddisk they make a lot of noise, and produce heat, is that a fact with SSD? (i'm not sure, but i think it's considerbly less.)

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