In the last post, we discussed some of the weaknesses of the hard drive – its relative fragility due to the basic design, its relatively high power consumption, and its relatively poor performance because of inherent latencies in its mechanical design. For some devices, even the smallest 1” hard disk drive may be too large (imagine, for example, a hard drive in your cell phone. Although a hard drive won’t be a good candidate for use in a cell phone, an SSD could easily meet the need for a hard drive).
The Solid State Drive overcomes the limitations inherent in the design of hard drives – but will probably always be limited in its storage capacity when compared to the hard disk drive. In this blog, we’ll take a closer look at the Solid State Drive (SSD).
A solid state drive is one that uses memory chips to store data, rather than rotating media. In a solid state drive, there should be no moving parts. The only things that should be moving are electrons, making their way through the memory chips that make up the drive.
Most of today’s solid state drives use Flash Memory – the same kind of memory that is used in USB Thumb drives and that is embedded into many devices. These devices usually allow you to ‘flash’ update code to bring a device’s firmware to its latest revision. (In this case, the word ‘flash’ is no mere coincidence). Other devices – such as medical test meters – have the ability to store test results even without power to the device – these use Flash memory to store the results. One of the most important characteristics of flash memory is its ability to store data even after power has been removed, plus the ability to easily erase and re-record data onto the memory.
Although there may still be solid state storage devices that use volatile Random Access Memory (RAM), the SSDs we’re looking at here use Flash memory.
The electronics built into SSDs perform a few functions:
- They emulate the interface of a hard disk drive, so that when attached to a computer, they look to the computer as if they actually were a hard disk drive.
- They control the writing and reading of data on the flash memory chips. This isn’t a trivial issue – it may be possible to control the logical patterns used to read and write to the chips so that the fastest performance can be accomplished. Also, although flash memory is designed to be read from and written to hundreds of thousands – or even millions – of times, controlling this process would help to assure that certain portions of flash memory aren’t used considerably more than others so that the drive does not prematurely develop areas of bad memory.
- They may also buffer reads and writes, potentially delivering data to the attached computer even more quickly than it is normally read from the solid state memory.
In the next part of this short series, we’ll look at some areas where the strengths of SSDs, compared to Hard Drives, can be best used…