If you ask me or someone familiar with PC hardware , that should buy something to improve computer performance , then the answer is usually " go buy an SSD ."
This advice is extremely true if your PC is already configured with 4 CPU 's strengths , 4 GB or more of RAM and a graphics card of intermediate segment ( mid -end ) or more . Of course, the laptop can be a bit different but still upgrade to SSD is the answer key . But this advice does not mean you can " say goodbye " to the HDD in today or tomorrow, or at least a few more years .
- Fast SSD but have long gaps
- Restrictions on semiconductor processes is a major challenge
- The technical problems will slow the process of replacing HDD
- The best choice for today is to use both SSD and HDD
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The nature of the SSD
In this paper , I refer only to the sale of common types of SSDs currently on the market is kind of based on NAND flash memory , more specifically, the model is used as HDD . In case you are more interested in SSD , a previous article on the history of the type SSD will be very helpful .
To give brief , no other SSD USB flash drive ( which we or wrong is called " local " USB ) is hosting several nature - are NAND flash . Flash NAND flash memory in particular and in general are composed of transistors ( trans ) should produce our way similar to DRAM memory chips or other kinds of processor ( CPU , GPU ) .
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Illustrating the potential and value of the bit .
These readers would learn about IT to know two numbers "myth " : 0 and 1 . These are the two basic building blocks to our world of today . But wait , the actual bit 0 or 1 is defined by humans , the trans does not understand what is 0 or 1 , we only voltage values . And we self-regulation that is in high voltage that is bit 1 ( or ON ) , the voltage is low, it is bit 0 ( or OFF ) . And this is the basis for flash memory operation .
Type trans flash memory used for FGMOS name or Floating - gate MOSFET , translated into the trans -effect ( field - effect transistor) MOSFET structure with a port types " float " ( floating ) . Wait again , you do not need to temporarily What is the MOSFET , just know FGMOS very similar to the type trans " popular " is used on the current CPU (excluding trans chip on Intel's Ivy Bridge as it goes towards other ) . The difference is crucial FGMOS add a port " float " between the gate ( gate ) and channels ( channel) . The first section in the following article will help you better visualize the problem .
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Transistor " universal " ...
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and transistors have gate " drift " .
A trans " popular " does not have the ability to store data permanently , it is merely a closed switch / circuit breaker current through leads . 1967 , two electrical engineers are Kahng and Sze were " repurposed " into the port it " drifting " as we have stated above . Called " drift " because the ports are not " conductive " to any component of the trans , it's completely isolated electrical conductivity due to the two layers above and below the insulating oxide ( ONO & SiO2 ) . You can similes it like a gateway FA ( forever alone ) also because it can not " talk" to one another if the person does not want to " talk" to it .
As featured " FA " her , the portal " drift " will not lose its voltage circuits even when power is removed . " FA " is what the company is worth to produce long -term storage ( non-volatile ) : you put into it a bit 0 , it remains 0 until many years later and back again ( unfaithful as FA right , where there is " flying butterfly " as we DRAM ? ) . Thus, a trans capable of "remembering " the birth data - flash FGMOS general and particular.
Why fast SSD ?
Over the top , you still do not understand why high speed SSD can be so. And more attention , you will see some " local " where there is a high speed USB , although it is flash memory ? The answer lies outside FGMOS nature of memory . I can summarize some of the following :
Logic operation of the flash chip ( SLC , MLC , TLC ... )
The number of channels ( channel) NAND run simultaneously
How to coordinate activities NAND channels ( firmware , controller )
Type of communication supports ( SATA , PCIe ... )
Operating Systems ( Windows , Linux , Unix )
On the logic of the operation flash chip , I would like to spend later ( after stating reasons will ) . Please pass the main differences between " drive " USB and SSD : NAND channels . Visualize as 1 CPU and 8 CPU 's . Although essentially the same, but one person than most people do at the same time , job performance will be different . NAND channels carry the same meaning , as a multi-channel operation, the working speed as quickly . USB flash drives are often only 1 working channel so low speeds .
Similar individual work and group work , only one channel , the working mechanism is simple , do not know to go there . But on the other channels . As a team work , there should be division leader to have everyone in the group . With SSD , too, need to have a controller chip ( controller ) to manage all NAND channels working at the same time . Imagine an 8 MB file each processing channel 1 MB ( 8 -channel ) , controllers need to understand each part of the file that is located in any flash chip ( chip flash SSD are more often ) .
And sometimes , company policy changes , the team leader must update the situation to reform the group . The main policy of the controller firmware . A firmware " stub " will make SSD performance becomes very bad and vice versa . There have been several instances where the SSD firmware update makes the storage device of the silicon ... brick ! Say , a USB flash drive controller also , but because of how simple the cost of the controller should also not high and almost nothing to improve the way of working . For ease of understanding , the controller 's USB flash drive rather " leper " , the SSD controller quite "genuine " .
Because there are many channels working simultaneously ( multi-threading , multi-channel , multi- line ... as you want ) , SSD 's performance is almost no theoretical limit may be increased because of continuous ( of course theory ) . Unlike existing HDD almost reached the limit of speed ( rpm disk blade ) , SSD can improve performance. It is important to communicate that this equipment is used to communicate with the computer must also be satisfied that speed ( we call that being " obstructive " or " bottlenecks " ) . Imagine such a plant is 10 tons but the transportation routes only meet 7 tons , which means communication is an obstacle in terms of speed . Need to higher SATA or other communication ( eg PCIe ) solution for SSD .
Final factor is the operating system ( OS ) . This is almost obvious because the new policy more progressive but conservative board of directors refused to support the efforts of both groups do not even nowhere . One of the most significant changes is the TRIM command support that the new operating system recently added support . If this command is not supported , the performance of the SSD will decrease .
But not as good as you think
SSD flash memory in particular and in general, there is an almost disadvantages of human cancers - a limited lifespan . Life expectancy is actually time " life " of the port " FA " . Not as HDD activity based on magnetic storage , flash chips based on the active storage electric field ( field effect ) . The changes do not wear magnetic memory cells but the voltage changes lead to chemical changes to the port on . Over time it will be active electrochemical corrosion gradually and at some point , no longer capable of storing information ( would you ever heard of " local " USB loved his life is about 10,000 times the deleted record ? )
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The lifespan of each type transistor NAND flash based on the number of write / erase .
But I do not mean to deepen this life . So clever engineers have devised our own ways to increase the amount of them to use . For example , " sacrifice " some flash chip to be used as buffer registers ( over- provisioning or OP ) , the trans basically OP will " die sooner " than the trans contain your real data , but the data you are safe. The algorithm " split " data ( garbage collection or GC ) to ensure the actual data will contain trans " are old " same as the SSD and the " dead " then basically , it is serving you well 6-7 years .
But what makes the SSD can not completely replace the HDD are located in the following section .
Maybe go far enough ?
The best Vietnamese in speed read / write and access ( latency ) of the SSD is not necessary to debate . Do not use a mechanical motor to rotate the electrical signals used to read data from a very fast SSD . Whenever looking for a certain file in piles of documents from the HDD , it is a " pain " to me because the latency is too high .
The problem of SSD longevity is now almost not a big problem because the algorithm helped manage firmware on the NAND flash trans " live " longer, especially OP higher capacity SSD as a " life " . So there is nothing obstructing complete replacement SSD HDD ?
Size & price . At first listen you can laugh SSD capacity is growing steadily if not called nearly caught up with the HDD . But over time , the cost , after depreciation of R & D expenses , costs will decrease . However, there is the immediate situation ...
How did the manufacturers ( NSX ) increase the capacity of the SSD ? There are 3 ways :
Increase the number of memory chips up ( 1 )
Increase capacity of each memory chip up ( 2 )
Change logic operations ( 3 )
How to ( 1 ) workable for the long term , production costs on old semiconductor lines will decrease , but the tradeoff is the size of the device will not be the same ( rather than having to accommodate more chips ) , power consumption is also higher .
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Capacity increases with the number of chips .
Method ( 2 ) is different. Currently most used models on the market SSD is used semiconductor process 30 - 40nm (typically 34nm ) . The model " advanced " than at 20 - 30nm (such as 25nm ) . Only new Toshiba reaches 19nm ( trans for memory chips usually smaller because fewer processor clock speed required over ) . The problem is : there are trans shrink to the point yet ? Until now , the semiconductor firm " oligarchy " is only the most well planned 14nm node in 2015 . And after that , almost ... indefinitely . Let's assume that after 25nm , 14nm SSD will move down and ... dim future .
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Capacity increase due to the small size of the transistors .
We left way ( 3 ) . Take a look back with bits 0 and 1 , note that this is the value of human poses ( logic ) based on the voltage of the gate " FA " . Assume that the bit 0 is 0V and 1V is the first bit . Between 0V and 1V Thus there is still a wide gap . Why not add some rules to the other more bit more storage ? The clever engineers have found our answer . 0V is for the 00 bit , 01 bit 0.3 V , 0.7 V is 10 -bit and 11 -bit level is 1V . Ie with a trans ( memory cells ) , we hold 2 bits than before .
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Capacity specified by the logic of the memory chip .
The method increases the logic bit is how we flash memory MLC (multi level cell ) flash memory compared to SLC ( single level cell ) .
Then why has not the 2 bits to 3 bits ? Okay , we have to flash memory TLC ( triple level cell ) . But this is when the problem arises : the voltage level of the specified bit too close together - they increase exponentially 2 ( 2 , 4 , 9 , 16 , 25 ... ) and it is difficult to distinguish between this bit with other bits . For example, 000 bits 0V to the voltage of 0.1 V , the 001 bits , 010 bits is 0.2 V. With these numbers you seem distinctive , but the effect is not a simple case .
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The voltage level corresponding to each bit in the NAND .
Please note that the trans not 100 % identical , will be at 0.09 ; 0.10 ; 0.11 ; 0.12 V. If only 2 or 4 voltage levels , it is not difficult to distinguish . But 9 levels and 16 even levels will be extremely difficult . But not read / write accuracy of the voltage , the controller will not give correct results . Think time record is 110 bits but reading is 111 bits , the harm will be like ?
Because of this potential overlap , but the NSX SSD not " dare " to invest more into the flash chip TLC or QLC ( quad level cell ) . They are really in laboratory studies , but the results are very bad . This is not taking into account the performance is reduced . Because only 2 SLC chip voltage level programming , it is faster than the 4 level programming (think pictures of stairs ) , TLC programming up to 9 levels and to change from low to high or vice it does take a fixed amount of time .
In addition, combined with the difficulty of how to ( 2 ) : the effect horizontally between the trans . When the trans standing too close to each other , their programming voltage can affect each other . Imagine you are studying by murmuring in his mouth , but stood too close to a person you are , you 'll be muttering influence and information stored in the brain is not seamless . Trans flash too, the bits of information can be disturbed .
HDD will live long
What I wrote above is not to decry SSD . Since upgrading to SSD is still questions I recommend anyone spend the first PC . But I do not tell people to go away HDD , as HDD nonetheless still have the advantage of size & price . Fair to say that progress SSD HDD is still making progress , at least in terms of capacity .
At one point , the SSD can completely replace the HDD , while the amortization of production costs helped price parity with HDD SSD . But it can be a time of " distant " than what you imagine . I personally think it takes 10 years , a new SSD HDD can push into the past . For now , a used PC SSD drive installed OS and applications , in addition to high-capacity HDD for data storage , is my advice for those who want to improve the experience for your PC .
synthesis
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