ssd 512gb More than just flash stacking! How much do you know about software algorithms in SSDs?admin
ssd 512gb It’s not just about stacking flash! How much do you know about software algorith msin SSDs?
external hard diskSSD OEM ssd 512gb SSD has become increasingly popularssd 512gb+8618750919058, now buy a computer without picking SSD’s ssd 512gb+8618750919058,” I’m embarrassed to say that I really understand user experience. Compared with traditional HDDs, SSDs are composed of flash memory, and the low latency of flash memory makes SSDs greatly surpass HDDs in terms of random read and write performance, which is also the key to SSDs to bring a smooth operation experience. However, SSDs are not just a simple assembly of flash memory, just stacking flash memory, ssd 512g bcan not be called SSDs. The software algorithm that invokes flash memory also plays a major role in the life, stability, performance and other aspects of the SSD. Do you know all the software algorithms in SSDs? Today, let’s talk about what software algorithms are in SSDs!
FTL: without it SSD can not be recognized
we all know that the hardware composition of SSDs is completely different from HDDs, so many of the mechanisms for operating systems to recognize HDDs do not apply to SSDs. For example, hard disk It is composed of platters, which are concentric circles, dividing the circles into small sectors, and the data is stored in these sectors, which are called sectors. The operating system organizes sectors to form file systems such as FAT32 and NTFS, so that users can access files/folders instead of the physical addresses of sectors. Basically, the basis on which the operating system builds a file system are sectors.
SSDs are made of flash memory, with no platters and naturally no sectors. (ssd 512gb)The basic unit of flash memory particles of SSD is the page (page) with a data capacity of 4KB, the Page constitutes the Block (area), the Block forms the Plan (plane), and finally the Plan forms the Die (wafer), which is the hardware architecture of the flash memory. It can be seen that the SSD has no sectors, what to do? This depends on some algorithms to convert.
an algorithm that virtualizes the architecture of an SSD into an HDD, called “FTL” (Flash Translation Lay）。 The FTL algorithm is provided by the SSD master and is more low-level than the operating system. As a software middle layer, FTL can map the Page-based hardware architecture of the SSD to the sector-based hardware architecture of the HDD. When the operating system creates a file system for the SSD, with FTL, the operating system sees that things are no different from HDDs, and you can use traditional methods to partition, format, and other operations on the SSD, without using a file system specially created for SSDs. Thanks to the FTL software algorithm, the SSD can seamlessly inherit the HDD, without which the SSD cannot be recognized.
GC garbage collection: without it SSD it is incredibly slow
The mechanism of flash memory is relatively unique, when you write data to flash memory, you must first erase the data in flash memory before you can write. Meanwhile, the smallest read and write unit for flash memory is Page, but the smallest unit for erasing is Block. A Block contains multiple Pages, and after the SSD has been working for a while, none of the Pages in the Block are blank. If you want to erase a block, you must first copy and back up the Page that has valid data in the block to another place, and then wipe it so that you don’t lose data.
where to copy the page of valid data to be backed up? Some of the worse products will copy the data of these Pages to the cache, wait until the Block is erased, and then write the data back, so that the write speed of the SSD is even more tragic – both the original data and the new data. What solves this problem is the GC (Gabage Collection) in the SSD, which is the garbage collection algorithm.
GC garbage collection algorithm looks a bit like defragmentation, it can move the Page of valid data in one block to other blocks, allowing the operating system to erase the entire block. Then write data to the block, so that you don’t need to write back the Page that was backed up to another place. CG occurs at the FTL layer, the GC algorithm of different SSDs is not the same, and the difference of GC algorithms deeply affects the performance of SSDs.
Trim: Greatly improves garbage collection efficiency
< p data-pid=”ksN0thsB” > Trim is an algorithm used to increase the efficiency of GC garbage collection. Without Trim, there would be a situation where a file is deleted in the operating system and the data is not actually deleted on a physical level. As a result, all the Pages of a Block of the SSD will be filled, and when the data is actually written, it will be forced to perform GC garbage collection, and the master will start to move the Page of the valid data to other Blocks, and then erase the Block. In this way, the speed is very slow, and the SSD has to GC first every time it writes data for a long time, and the user experience is very bad.
< p data-pid=”zNDT-cpR” > Trim can greatly alleviate this situation. After the operating system deletes the data, Trim tells the SSD master which Page data corresponds to the deleted data, and these Pages are marked as invalid Pages. Then, during the leisure period, the SSD master will take the initiative to CG, remove the page of the valid data, and then erase the data of these blocks, and prepare enough blocks for the data writing of the operating system in advance. In this way, even if it is used for a long time, as long as the SSD is not too full, the performance will not have too obvious decline, which greatly improves the user experience. The Trim algorithm is provided by the operating system, Win7, Android 4.3 and later operating systems support Trim.
wear balance: to ensure that flash life is evenly consumed
< p data-pid=”TMaRFKiA” > We know that flash memory has a rewrite life, for example, MLC flash memory can only be erased thousands of times, TLC flash memory can only be erased hundreds of times, and so on. In fact, with the current SSD capacity, the total amount of erase data is very amazing, such as 256G SSD, the life is 500 erasure (P/E), then you need to write 125TB of data, flash memory is the end of life – even if you write 10G data every day, you also need to use more than thirty years to write flash memory, not to mention that few people write 10G data to the SSD every day.
but many friends still do not trust the life of the SSD, on the grounds that the life of the SSD is estimated according to the overall capacity. Some friends believe that when reading and writing data, they will concentrate on reading and writing part of the flash memory of the SSD, and the flash life of this part will be particularly fast. Once this part of the flash memory is hung, then the entire SSD is also hung. But is this really the case?
of course this is not the case. In fact, SSDs have a Wear Leveling algorithm that makes the wear and tear of all flash memories as consistent as possible. The wear balancing algorithm of SSD is roughly divided into dynamic and static. The dynamic algorithm is that when new data is written, it will automatically write to the new block, and the old flash memory will be put aside to rest; The static algorithm is more advanced, even if there is no data written, SSD monitors that some flash blocks are older, and will automatically allocate data, so that the older flash blocks undertake the storage task of not writing data, while making room for the newer flash blocks, and the data reading and writing on weekdays is carried out in the newer blocks – so that the life loss of each block is almost the same.
SSD is by no means made by stacking flash memory together, and it depends on various software algorithms to make SSD run stably and quickly. When selecting an SSD, you can pay more attention to the master control scheme used by the SSD and pay attention to whether the algorithm of the master control is reliable; When using an SSD, choose the appropriate operating system and update the firmware and drivers of the SSD in time. In this way, you will get a better experience.
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