About SSD FTL Data

1 Jun

1. master how stable?

SSD controller stability is very reliable, and under normal circumstances would not have problems, embedded ROM will not inexplicable damage. (If damaged, you can buy a lottery ticket)

2.NOR Stability How?

Fengyun NOR stable than SLC but also reliable, so under normal circumstances it will not be this component hang. (Unless the firmware when you brush down)

 3.NAND Stability How?

SLC, MLC or TLC, stability can vary widely, the factory bad block is granted, the data in the above operation, the pressure is so great, the risk of error naturally larger than the above two more.

Therefore: master physical damage, buy lottery tickets. NOR physical damage, the theory is for a re-production (of course, no such tool users, Depot bar). NAND physical damage, data finished.

 To put it bluntly, the so-called NAND data error, refer to the current non-original read data when data is written (by a variety of algorithms, adjustment processing can not restore the original data), so the vast majority of cases, out of disk and change Bricks are made due to the following two conditions:

 FTL damage caused by the user data address can not find it. (Can cause a variety of situations, pure look at the RP, of course, the most common in high-stress occurs when writing down and so on.)

firmware bug in certain cases lead to logic errors, lock plate and so on.

SSD is non-normal power-down will cause data corruption is being written, and these data is divided two categories, the data transmitted from the host, the other is the internal operation of SSD FTL data. Generally, SSD firmware is required in any case guarantee SSD when the next power of the original data to be read out (either by correction or adjustment is good). But everything is not absolute, there will always be unexpected happens, such as data access FTL has gone wrong, the direct result of SSD swap disk, there are some kinds of critical data loss or errors FTL even contradictory, then it can not determine Where is the correct data.

Assuming SSD firmware where for each Page are marked “Who am I”, and FTL record “Who Is.” When FTL As mentioned above, a variety of unpredictable reasons, led to some damaged or completely destroyed, then we lost the “Who Is” This part of the record, and naturally can not find the data we want. Now we do a reverse thrust operation for holistic Page do a full scan, the scanning speed depends on the capacity of the SSD, which is “30 minutes” the origin, so that every Page are reporting times, “Who am I”, and then follow the FTL report regenerate a record, you can recover all or most of the user’s data, which is from the original “bricks” into a re-identify the SSD state. As for the feasibility of this method of operation, for example, two data point to the same LBA, how can we judge these two old data? Micron firmware design is part of the essence. Then the recovery operation can not have a graphical interface it? So the user at least know they are doing a disk repair ah, the answer is no, ATA protocol is not supported.


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