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Posted by on Jun 19, 2013 in Hardware |

All you need to know about solid state drives (SSD)

All you need to know about solid state drives (SSD)

Repeatedly touch this issue and believe it is time to explain it properly. We talked about solid state drives, also known as stands for Solid State Drive, devices that are now so common and wild all computer class and entered as a replacement for hard drives.

But what are they? What is the difference between hard drives? What are its advantages and disadvantages? Why all the PC manufacturers now use them? In the most direct way possible try to answer these and other questions, revealing everything you need to know about SSD and apparent mysteries …

SSD vs. HDD

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For years, the solution for mass data storage in a computer has been a hard disk. This stores the installed operating system files, music, videos, etc., depending on turntables which retain the information and are read by a head much like turntable.

But SSDs work differently. Assimilating to a RAM, these new storage units exchanged by small rotating disk flash memory chips to deliver capacity, being unnecessary a head for reading data since everything is done electronically through a controller.

This allows the SSD has no moving parts, that is, not having parts that are moving physically as a rotating disk with a head that seeks sectors, allowing the new technology is of smaller physical size and present a number of other advantages that place it above the traditional hard drive.

Advantages of SSD

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Being made up of flash drives that are solid state semiconductor, we can see some advantages illustrated as follows: imagine the competition between a CD and a flash drive or removable flash memory. Here is, as it changes the storage model from spinning disks to solid electronic chips.

Therefore, the most obvious advantage is resistance to beatings and mistreatment, as not having moving parts, the drive is less delicate. For a long time we saw on hard drives fall protection systems, which slowed the hard drive if it came a heavy fall. Now that is no longer necessary, because like a flash drive, inside there is nothing to move and could be damaged.

But the most important advantage is on the side of performance. Hard drives are old technology, such as a CD it is to pendrive as memory chips empower the computer for more rapid access to information, which is the speed that allow semiconductor and controller . Instead, on a hard disk spinning plate and head had to physically locate the file, delaying the task.

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Thus we see that modern hard drive reaches speeds of writing and reading close to 100MB/sec data on a disk that spins at 5400RPM or 7200RPM. On the other hand, an average SSD 500MB/sec easily reached. This directly affects the user, since the higher speed data on a PC, the faster the programs load and start the operating system.

Access times also improve on an SSD compared to a hard disk. Because thus depends on the speed of the semiconductor, an SSD takes about 0.08 ms to find the information you are looking for and start the transfer, while the average time it takes a hard drive to do the same is 12ms. So another advantage of SSD is its low response time to carry out orders.

With a SSD also enjoyed a little noise, since there is no head reading and writing data on a plate, while the absence of such work and associated motors decreases energy consumption of the device, while reducing the temperature to it works and eliminates vibration.

Disadvantages of a SSD  

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It all sounds wonderful with a solid state drive, but there are disadvantages? As happens in life, good things are expensive, so it looks like SSD main disadvantage of its high price relative to traditional hard drives. 500GB of capacity on a SSD currently cost between $ 400 and $ 500 in the U.S., while a hard drive of equal capacity is USD $ 60. And that the reports dropped significantly in price in recent months.

That’s why generally pre-assembled computers (such as laptops) that bring SSDs also come with small storage capacity, still possible to find cheap computers with 500GB hard drive and expensive equipment but of 128GB SSD, so the issue of space must be considered if one chooses to use a solid state drive.

Moreover, when they started to be marketed these products were associated with other problems currently already in the past. First, degradation of the memory chips reduced the unit performance after a long time of use. Then came technology to be integrated into the product, improved this situation and allowed the problem to be forgotten today.

SSD types

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There are several ways to classify solid state drives. Firstly, do the differentiation with respect to how they are connected to the computer, there are two kinds of major ports by which we make the connection between these devices and PC motherboard :

  • SATA port is the most common by now also connect hard drives. On your desktop PC version, consisting of a thin cable from the drive to the motherboard. There is also mSATA, which only gives the port to connect directly, serving for notebooks and laptops.
  • PCI Express: Commonly used for video cards in a desktop computer, this port is high speed for professional performance models are around 1000MB/seg or 2000MB/seg, being great cards (pictured) to open a new category SSD for demanding users who have lots of money, and are expensive. PD: Samsung is starting to make small PCI Express SSD for laptops en masse, so beware.

On the other hand, we can differentiate the SSD as the type of memory used:

  • NAND Flash Memory: The most commonly used are silicon chip is also used in flash drives and has a non-volatile memory, ie, even when it has energy is able to save the data you have recorded.
  • DRAM Memory: More expensive and less common, DRAM memory modules are the same as those used in the RAM, allowing greater speed and faster response times. They are unsuitable for everyday SSD because they require continuous power to “remember” the data they have recorded, however, offer exceptional performance.

Finally, we will make the distinction between the types of technologies that are used to form NAND flash memory, existing three categories:

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  • Single Level Cell (SLC): When you get a silicon wafer and cut to obtain a single memory chip, born drives. Being simple, they are the fastest and lowest energy consumption, but are the most expensive to manufacture of all. You can write only two states (empty or full block block) and there are positive properties.
  • Multi-Level Cell (MLC): When stacking several layers of a silicon wafer, we get a NAND flash memory chips. It is the most commonly used because they are more dense, allowing higher capacity in the same space, also meaning a lower price (three times cheaper than SLC). However, the chips are slower and less lived than SLC. They are written in four states (in the picture).
  • Triple Level Cell (TLC): The most economical of all are worth 30% less than the MLC. They are dense and thus, you can get high capacity digital storage little space and are written in eight states, coming from there its economy. But they are slower than the and have a shorter life time, allowing only between 1,000 and 5,000 cycles of writing and reading to become unusable (SLC: 100,000 cycles, MLC: 10,000 cycles).

A little of the SSD …

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Although difficult to believe, the first device that can be considered a was the model company Core Bulk Dataram, released on the market in 1976. Contained eight memory modules with a capacity of 256KB each, giving total storage 2MB chassis 50 inches wide. It cost about USD $ 10,000 at the time, what today might be USD $ 40,000 if we consider economic inflation. And it was in RAM, rather than chips especially made for SSDs, as the current MLC or SLC clearly did not exist back then, so it was necessary to stack RAM to achieve the same goal.

Thereafter the products that existed remained the essence of being “RAM disk”, as the firstborn, costing brutal amount of money to be gained. That is until 1988, when the manufacturer created the first flash mass storage. Called NOR flash chips allow these modules to 16MB capacity for $ 5000.

During the entire decade of the 90s the category continued to grow primarily in the area of professional servers, until in 2003 the company released a model that was connected to general market PCs through Parallel ATA IDE port, being the common use at the time. The larger model was used 512MB and flash memory, so you could say was the first product that honestly looked massively.

From then on come the mass arrival of the SSD: from 2006 onwards Samsung, Sandisk, Intel and several other manufacturers specialized in this kind of products, technologies developed SLC, MLC, TRIM and several more of the sights today. Arguably, the development was rapid, and in less than seven years have passed modules expensive to cheap 32GB 250GB, integrating massively in several models of notebooks and also offering a low price on separate drives to update all the PCs

So, no doubt we live today the best time of the SSD, as the price of flash memory has dropped significantly in recent months and it has broken the psychological barrier of “one GB per dollar,” finding models which may even lower costs. The golden age of this technology, one might say, is just beginning.

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