Throwing a Glance at Solid State Drives

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With the rapid state of technological growth lately, it's important to remain vigilant in order to keep up to date on the latest releases. This article will specifically dive into the status of solid state drives and the future of data storage. Read on to find out more.

Lately we've been experiencing an exponential growth in all areas of technology. It takes constant motivation to keep up with the pace of this evolution, especially in the fields of computing and electronics. The traditional classic HDDs that most of us are currently running are based on technology principles that are more than 30 years old.

However, things could change in the near future because Solid State Drives (SSD- often called Solid State Disks because they behave like disks) are rapidly emerging. SSDs are data storage devices based on solid-state memory architecture. These drives are able to emulate a traditional magnetic HDD and because of the obvious speed improvements they're capable of taking over the storage market.

In this article I'm going to hook you up with the tech tidbits on SSD architecture, telling you how well these SSDs perform and their main advantages and drawbacks. I'll also draw a short comparison with current conventional HDDs, and then ultimately you will find a conclusion and a short buyer's guide if you prefer the latest and greatest.

SSD Architecture

Solid state drives are designed and manufactured on the solid-state architecture. This means that they do not contain moving mechanical or magnetic parts like rotating platters or heads. Their electronic circuitry is built entirely out of semiconductors. Therefore, you should think of an SSD like a relatively large flash drive.

There are two types of solid state drives, each built on different technologies:  volatile SDRAM-based and non-volatile NAND flash drives. The SDRAM ones are typical for computer RAM; data cannot be stored permanently (they require batteries). Throughout this article we'll cover only SSDs that are based on the non-volatile NAND technology. This is the same technology used for flash drives.

Non-volatile flash drives are able to store data permanently without requiring the user to constantly power on. Due to this, manufacturers designed SSDs in the form factors of hard disk drives as well as their interface (ATA/SATA) for compatibility reasons.

Now let's talk about electronics for a moment. At first, flash memories needed to be erased entirely each time new data was to be written. Nowadays the latest generations of flash memories have the ability to erase and write on blocks instead. This is possible because of the cells that are made of the floating-gate transistors connected in a matrix-like design (two-dimensional array).

Electrically it is possible to write and erase these cells independently. Also, once they're "filled" with information, their ability to store this data long-term is very efficient. Two types of cells exist: the SLC (single level cell) that can store only 1 bit per cell and the MLC (multi level cell) which can store multiple bits per cell.

A few paragraphs ago I mentioned "NAND" as a technology without further clarifications. The logic gates on which flash drives are designed can be either NOR or NAND. Solid state drives are designed on the latter. Basically it stands for a digital logic gate that works in the following scheme (truth-table): the output is 0 if and only if both of the inputs are 1; otherwise it is 1. All of the 4 options are clearly pointed out below:

1 NAND 1 = 0; 0 NAND 1 = 1; 0 NAND 0 = 0; 1 NAND 0 = 1.

These NAND gates are used in many digital system designs because they can efficiently replace many of the alternatives (OR, AND, NOR); ultimately, they yield more compact results for manufacturers. That's why these types of gates are used for CMOS and TTL as well as the heart of flash drives like we discussed.

Check out the following picture of a Samsung 4GB SSD. Pay close attention to the interiors. You can see those four black ICs (integrated circuits) that are the memory chips and the big black IC in the middle that is the ARM microcontroller (Advanced RISC machine) manufactured by Samsung.

(Samsung 4GB SSD -- photo courtesy of laptoping.com)

Next: Advantages of SSDs >>
 

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