July 18, 2024


Law, This Is It!

Take a look at Principle and Primary Factors of SSD Electricity – Down Protection

5 min read


Stable-condition difficult generate If you ought to use FTL to do the sensible address and the bodily deal with concerning the conversion, if the SSD browse, produce, delete and other typical perform in the circumstance of irregular electric power-down, might bring about mapping desk because of too late to update and dropped There is a fault that the SSD can not be regarded by the system.

At the similar time, in order to increase read through and create efficiency, normally use SDRAM to do the cache, if the procedure of reading through and creating encountered abnormal ability-down, SDRAM facts may be too late to create Nand Flash facts loss, or update the mapping table far too late to create Nand Flash The mapping desk is lacking.

Abnormal power failure caused by the phenomenon

SSD abnormal energy failure generally there are three types of failure phenomenon:

1, SSD can not reproduce the procedure identification, the need to rebuild the mapping desk or by simple and crude way to re-output can be utilized

2, quite a few moments right after electricity failure, SSD there are a ton of “new negative block”

The mechanism guiding the new bad block is that when the SSD reads, writes, or erases unsuccessfully, it will be discovered as a poor block. Of class, these blocks are not actually undesirable blocks, just for the reason that they are abnormal Electric power failure prompted by the incorrect judgment.

3, SDRAM knowledge reduction

Typical electrical power-down defense system

Each electric power-down protection system to comprehend various, distinct for the person, the safety system is wholly unique, normally there will be the next two practices:

1, save all the information in SDRAM

Irregular electrical power-down, SDRAM all knowledge will have to be totally prepared to Nand Flash, in normal, SDRAM ability is set to 1000% of the amount of SSD bare capability, for small capacity SSD, SDRAM want to compose Nand Flash details Fairly modest, by way of the tremendous capacitor or tantalum capacitor can go on to produce facts. Even so, if the SSD capacity is big enough, for example: 8TB, then, SDRAM will need to write Nand Flash info will be incredibly substantial, if nonetheless depend on tremendous capacitor or tantalum capacitor to do ability offer, will inevitably facial area the following three tough dilemma:

a, the want for more tantalum capacitor particles to do the safety, in the genuine engineering follow, this is a really really serious exam, the engineers encounter the thickness, the standard size limit, PCB space is not plenty of to use

b, even if there is more than enough capacitance to do the protection, when the implementation of the “restart”, the SSD will not start out adequately, you have to to start with shut down for some time prior to restarting, because: SSD need to place all the tantalum capacitor after power Recognized

c, when the use of a number of decades soon after the tantalum capacitor or tremendous capacitor just after growing old, when the tantalum capacitor electrical power offer can not attain the preliminary design and style goal price, the user nevertheless has facts reduction immediately after electric power decline or SSD can not recognize the possible risks, if the first structure That is, to do redundant capacitors, then, will return to the challenge “b” loss of life cycle.

It is gratifying that the issues of b and c are fantastic remedies to remedy these thorny difficulties only will need the engineers enough intellect and working experience only.

2, only conserve the SDRAM consumer data, without conserving the mapping table

This will lower the use of SDRAM and the use of tantalum capacitors, “do not conserve the mapping table” does not signify that the mapping table is lost, just do not help save the past details write update map, when the SSD re-power, Looking for the last mapping table to help save the new info composed to re-develop the mapping table, the downsides of this method is not adequate system to established the sensible, then rebuild the mapping table will be for a longer time, SSD will take some time to typical obtain to regular

For controllers without having SDRAM design, all information is created specifically to Nand Flash. When facts is shed, the details that is not prepared to Nand Flash will be returned to the host. If no additional data requires to be saved, Superior reliability demands of the application, no SDRAM design is king, its consultant is a German industrial brand grasp, its only disadvantage is that the functionality is not superior sufficient, in actuality, lots of applications and the have to have for the highest functionality, and Is “more than enough” effectiveness.

Examination solutions and concepts

Distinct take a look at, SSD need as a process disk and as a disk from the two scenarios of screening, so the main disk and do from the disk test strategy is the only difference is that the most important disk need to have to exam the laptop or computer to ability off the machine, and from the disk only SSD can be on the ability off.

a, respectively, of the SSD as a blank disc, details is penned in the 25% and 50% when writing info, the write information for 85% and 3000, respectively, the abnormal electrical power down 100% check produce data, every down And the electrical power-on time interval of 3 seconds

The principle of crafting unique ability details to the disk is: When the SSD write a particular volume of information, the qualifications started to rubbish assortment, garbage selection indicates that the relocation of details, information migration implies that the mapping table updates, at this time Abnormal ability failure is ordinarily a difficulty.

b, when the normal write info, the SSD irregular electricity-down

c, when the data is deleted when the irregular ability-down

In the windows, delete the information also need to complete 8 actions, and the establishment of the similar doc, the mapping desk also will need to update.

d, when the SSD go through file is abnormal energy down, test 3000 times, electric power off time interval of 3 seconds

e, when the usual shutdown procedure irregular power down, examination 3000 instances

f, when the regular start out of the operating procedure irregular power down, take a look at 3000 periods

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