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 Post subject: LDPC and ECC Explanation
PostPosted: December 26th, 2022, 23:45 
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Joined: April 17th, 2022, 22:39
Posts: 44
Location: Vietnam
Hi everyone,

I recently just started out on Flash Recovery and heard a lot about LDPC and ECC

I have googled, and read through LDPC and ECC on google search. And have some description about those 2 things. However I still have very small understanding about them and what they do to the Monolith, Flash, and what do they do to Recovery in general.

I would love to understand more about the situation of SD, Micro SD, Flash situation right now.

And would love to learn more about LDPC and ECC that affects our Recovery Community. Will it be cracked in the future?? and how far are we to achieve that??

Would love to read some books, some posts, videos about them and about our situation right now of Flash Recovery?

Many Thanks!


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 Post subject: Re: LDPC and ECC Explanation
PostPosted: December 27th, 2022, 4:48 
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Joined: October 24th, 2009, 15:22
Posts: 872
Location: Poland
Maybe start from BCH. It is implemented at all flash recovery tools and looks simpler than LDPC:
https://en.wikipedia.org/wiki/BCH_code

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 Post subject: Re: LDPC and ECC Explanation
PostPosted: January 12th, 2023, 15:09 
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Joined: December 4th, 2022, 12:25
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Location: United States
You can find some educational videos about them on YouTube.


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 Post subject: Re: LDPC and ECC Explanation
PostPosted: October 17th, 2023, 23:20 
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Joined: December 4th, 2012, 1:35
Posts: 3844
Location: Adelaide, Australia
watch this thread.
https://forum.hddguru.com/viewtopic.php?f=13&t=43582


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 Post subject: Re: LDPC and ECC Explanation
PostPosted: October 18th, 2023, 14:11 
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Joined: June 11th, 2013, 17:01
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Location: Phoenix, AZ USA
Looks like you are just starting out so to put it in its simplest terms. Flash memory is in a constant state of degradation. The simple action of writing data to a cell degrades it. So ECC (Error Correction Code) is a way to reallocate the data in those bad cells/blocks to other areas. LDPC does a similar thing, but uses complex mathematical calculations to achieve it. No one has successfully reversed engineered LDPC algorithms yet. So any flash device that uses LDPC is generally not recoverable to chip-off/pinout methods. That may change in the future as technology develops.

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 Post subject: Re: LDPC and ECC Explanation
PostPosted: October 18th, 2023, 17:45 
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Joined: October 3rd, 2005, 0:40
Posts: 4311
Location: Hungary
to put it clear: ECC isn't relallocating anything, it is an applied redundancy in a way that the controller can find out where bit errors are in the read data so that it can flip these (correct the errors). LDPC is a way of ECC, just like BCH, Reed-Solomon and some others.
ECC stands for Error Correcting Code, the algorithm can vary, just as the error correcting capabilities of the code.

pepe

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 Post subject: Re: LDPC and ECC Explanation
PostPosted: October 18th, 2023, 17:55 
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Joined: June 11th, 2013, 17:01
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pepe wrote:
to put it clear: ECC isn't relallocating anything, it is an applied redundancy in a way that the controller can find out where bit errors are in the read data so that it can flip these (correct the errors). LDPC is a way of ECC, just like BCH, Reed-Solomon and some others.
You are right, I was over simplifying for the OP.
pepe wrote:
ECC stands for Error Correcting Code. pepe
We do disagree on that, but its just semantics ;-)

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 Post subject: Re: LDPC and ECC Explanation
PostPosted: October 19th, 2023, 6:06 
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Joined: August 10th, 2015, 9:00
Posts: 33
Location: asia india
Which devices implement LDPC ?Where can I get more details of SSD microcontrollers there working etc. Currently I outsource my ssd work to a frind having pc3000 portable but nearly 90% cases are rejected for the reason mcu not supported
I am wondering how flash recovery guru's like arvika & others do these recoveries .
Besides ace portal where is more details of latest ssd manufactures and controllers they use etc.
Thank You


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 Post subject: Re: LDPC and ECC Explanation
PostPosted: October 22nd, 2023, 8:36 
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Joined: December 4th, 2012, 1:35
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Location: Adelaide, Australia
>>Which devices implement LDPC ?
USB flash drives and SD cards for example. You likely won't know until you dump them.


>>Where can I get more details of SSD microcontrollers there working etc. Currently I outsource my ssd work to a frind having pc3000 portable but nearly 90% cases are rejected for the reason mcu not supported.

This is likely not due to LDPC only, but no-one has successfully done the reversing needed to support those SSD's. Info at a technical level? Not easy to come by.


>>I am wondering how flash recovery guru's like arvika & others do these recoveries .
They have built their knowledge up over many years of hard work and Many, Many successful and failed cases. They have studied their tools and all the available information, and done some true research on their own. of course there are a few other factors, but do not make the mistake of thinking these guys have it easy!


Besides ace portal where is more details of latest ssd manufactures and controllers they use etc.

It may be a better idea to identify what details you need, and then go after that. Vacuuming up info will not really help you.


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