Last month we looked at the Dell Inspiron Mini 9 netbook and its mobile features. One of the prominent aspects of the Mini 9 (and most other netbooks) that I wanted to review in greater detail is the solid state drive (SSD) technology that it employs as a data storage solution, and how SSDs differ from other hard drives. For the purposes of this article, I want to look at SSD vs. hard disk drives (HDD) technology as it pertains to mobile computing -- particularly in netbooks.

Traditional hard drives are highly mechanical in their design. Data is stored on circular platters that spin at speeds of up to 7200 rpm when the drive is in operation. The data is retrieved from and written to these platters by read/write heads attached to an arm-like mechanism that moves back and forth from a hub. This process can take place upwards of 50 times per second.

SSDs, however, are constructed entirely out of semiconductors and function in similar fashion to flash memory devices in terms of data storage and retrieval. Unlike HDDs, however, solid state drives contain no mechanically designed parts at all.

Solid state drives offer a tremendous advantage over traditional HDDs, particularly in mobile computing, in that there is no risk of mechanical failure because there are no moving parts to contend with. The drive is also much more quiet and requires significantly less cooling because of its non-mechanical design.

Boiling it down, you never have to worry about the drive failing to spin up or the arm breaking, because they simply don’t exist in SSD technology. As someone who has broken his share of hard drives, this is a very nice development.

Also, because there are no mechanical parts that require power to function, SSDs have significantly less power requirements than their HDD counterparts. Again for mobile computing, this is a major advantage as you now have one less high-energy component depleting your all important battery life.

Because there is no need to spin up platters to read and write data, SSDs see an increase in read and write speed as well. Like any other hard drive, however, the degree of speed increase you experience is directly proportional to the money you spend on the drive. More cash equals faster results.

It is worth noting here that all SSDs are not created equal when it comes to speedy data access. For netbooks in particular, the functionality of your machine is greatly dependent upon the write speed of the drive. Write speeds on SSDs can vary between 15 megabytes per second all the way up to 80 megabytes per second, with the price of such devices scaling accordingly.

For the best results, you want a SSD that falls in the 25MB/s to 60MB/s range. Anything slower than 25MB/s is going to cause noticeable slowdown when trying to run any application on your machine. Anything faster than 60MB/s is really a waste because netbook hardware just can’t keep up with the speed. The sweet spot as far as write speeds go is usually between 45MB/s and 50MB/s for netbooks.

That being said, solid state drives currently have two significant disadvantages working against them: cost and capacity.

Theoretically speaking, let’s say I have $120 to spend on a quality storage solution. For my money, I can get a very nice 32GB SSD with around 45MB/s write speed and a built-in micro USB adapter. For that same cost, I can also get a 1.5TB (yes, I said terrabyte) traditional SATA (Serial Advanced Technology Attachment) drive. That’s a significant difference in storage capacity between two devices that carry identical cost. With the SSD, I’m getting about 267MB per dollar I spend, whereas I’m getting 1.25GB per dollar with the SATA drive.

For netbooks, the small capacity isn’t as much of an issue because the machines are designed primarily for mobility and aren’t expected to run intensive applications or function as a primary hub for data storage. Still, you’d be surprised how quickly you can fill 32GB of space before you even know where it all went -- especially when the operating system takes up anywhere from 9-12GB of space all by itself.

Functionally speaking, SSDs are easily superior to HDDs in my opinion. Higher costs and lower storage capacities, however, are currently preventing the technology from being more widely implemented. And who can blame the consumer for wanting more raw storage for the money?

There are high capacity SSDs out there, but they are exorbitantly priced. So goes the trend of developing technology, it seems. The prices are trending downward, however, so there is good news on the horizon for those of you looking to try one out for yourself. It may be 18-24 months before SSDs are competitively priced alongside HDDs, but I think the wait is worth it.