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 Post subject: a very silly question in configuration
PostPosted: July 26th, 2017, 15:05 
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Joined: March 5th, 2012, 11:17
Posts: 27
Location: argentina
Hello every on?
Look i have a question about the parameters in the configuration to read the memory, in the section about the page size block size, there are 2 columns nominal and real. Why this difference?

and another cuestion is i have 2 memories the page size in configuration is much more big the one i see in the bitmap viewer, why this hapen?

Thanks very much my best regards


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 Post subject: Re: a very silly question in configuration
PostPosted: July 26th, 2017, 17:40 
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Joined: April 3rd, 2011, 0:19
Posts: 1591
Location: Providence, RI
I'm not a flash guy (so nobody shoot me here if I'm off base) but I'm pretty sure it's because each page contains a block of system area data (ecc, etc.). So the nominal size is how many logical bytes, real is the size after you factor in the extra system area bytes.

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 Post subject: Re: a very silly question in configuration
PostPosted: July 26th, 2017, 20:39 
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Joined: December 4th, 2012, 1:35
Posts: 2876
Location: Adelaide, Australia
Not a silly question at all. This is how I see it, and welcome corrections.

Both Nominal and Real include the Spare Area (What data-medics is calling System Area).
some drives have very slightly different sizes.
The Nominal size is usually a pretty standard size such as 2112, 4320, 9216, 17664.

Think of the replacing "nominal" with "we will call the size". Or we could say it is 2Kb page size or 4Kb, bit be slightly bigger in reality

There may be some bytes at the end of a page that are not used, I call them padding. not used for data, SA or ecc, or anything at all. so if you only count the actual used bytes up until the start of that, then that would be nominal, the whole page including these bytes would be real.
I *think* this is what the skip_mask entries in the NR config is about.

can you show a screenshot of the page size/bitmap issue you are talking about?

Always good to talk to Sasha or tech support about config if it isn't working out, as a tiny error can leave you banging your head against the wall.


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 Post subject: Re: a very silly question in configuration
PostPosted: August 7th, 2017, 10:19 
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Joined: March 5th, 2012, 11:17
Posts: 27
Location: argentina
Thanks very much HaQue, i am stil working in this case, from rusolut support they giveme advices for this case


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 Post subject: Re: a very silly question in configuration
PostPosted: August 7th, 2017, 10:25 
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Joined: December 4th, 2012, 1:35
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Location: Adelaide, Australia
You are in good hands.


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 Post subject: Re: a very silly question in configuration
PostPosted: August 8th, 2017, 4:12 
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Joined: August 13th, 2016, 17:10
Posts: 40
Location: Vienna, Austria
A question regarding the naming: I would expect that "System Area" and "Spare Area" are 2 different things:
System Area is for storing firmware modules, configuration, SMART, ...
Spare Area is for providing sectors as replacement for G-List.
Am I wrong, are both the same?


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 Post subject: Re: a very silly question in configuration
PostPosted: August 8th, 2017, 19:38 
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Joined: December 4th, 2012, 1:35
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Location: Adelaide, Australia
You are using HDD terms here. Forget them.

Spare area is part of the page, or other parts that are not DATA. It can contain page, block, sector numbers, test bytes, padding, other bytes that indicate things like versions of the page.

Also the context matters.

If you are talking about reading the NAND for a complete dump, then really you are interested in getting a complete copy of the chip, then parsing it using info from Spare Area. You break it down into blocks and pages, reverse whatever manipulations the controller did to start to rebuild the DATA .. it could be a disk image, raw custom file system etc.. this is where you start to talk about system / firmware etc.

Of course like everything, the terms can get used flippantly, but as long as you know the context, you should be ok.

Also, the actual schemes that vendors use vary a LOT. So you will see pretty much anything you can think of. It is Rule 34 for NAND basically!

Flash don't use the term G-List.

If you break it down like when reading a chip and talking about dumps:

chip / crystal / plane / bank / block / page / (DATA / Spare Area / pad) / byte / bit

you should be ok, then pickup all the nuanced cases as they arise.


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 Post subject: Re: a very silly question in configuration
PostPosted: August 10th, 2017, 8:03 
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Joined: November 9th, 2006, 15:15
Posts: 2917
The manual explains what this is:

'Nominal and real block size value are used only in the case of TLC (Tripple Level Cell) flash memory chips. Usually in those chips nominal block size is multiple of 4, but real block size is multiple of 3. For example, if nominal block size is equal 256 pages, real block size is equal 192 pages. The remaining 64 pages are addressed inside flash memory, but physically they are not exist. '


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