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 Post subject: Question regarding settings
PostPosted: August 11th, 2022, 7:27 
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Joined: July 23rd, 2018, 2:19
Posts: 14
Location: north of the wall
Got a defective SSD with a Marvell 88SS9175 controller and 4x SanDisk 05055 064G (id 453ea782) chips on it.

When saving the "decrypted data" (aka descrambled data) using the functionality under "Test - > Utility tests -> Dump savings" we get clear text data, however, we're a bit unsure on one setting that must be specified in the "Tests -> Utility tests -> NAND" setting page.
Here you are asked to enter "Blocks per plane", but this term is a bit vague since PC3000 uses a different terminology from e.g. Rusolut VNR.

If we identify the chip with Rusolut VNR, we get the following data:
Page size: 8832 bytes
Block size: 256 pages / block = 2260992 bytes
Plane size (nominal): 8192 blocks / plane = 18522046464 bytes
Plane size (real): 4196 blocks / plane = 9487122432 bytes
Chip size: (nominal): 8 planes / chip = 148176371712 bytes
Chip size: (nominal): 8 planes / chip = 75896979456 bytes

Now the interesting question is, what do these numbers translate into for the PC3000 settings?
PC3000 specifies:
4 chips
STAR count: 8
Banks per STAR: 1
Channel count: 4
CE count: 1
LUN: 8
Planes: 4
Page size: 8832 bytes
Block size: 256 pages / block = 2260992 bytes

In order to get descrambled data at all, we have to specify this "Blocks per plane" value in PC3000 as well, but what is the correct value? The different terms between the different software makes it a bit confusing.

Also, in order to reconstruct the data, would it be possible to first do a read of each NAND chip with PC3000 using the descrambled data functionality (that gives data stripped for spare area bytes), and the do a raw NAND read of the same chips (that includes the spare area bytes) and concatenate the spare area bytes only from the raw NAND read to the descramble read in order to do the translation of the data to a file system?

E.g. if the page structure of the raw NAND is
[160 bytes of spare/ecc | 2048 bytes SCRAMBLED data] | [160 bytes of spare/ecc | 2048 bytes SCRAMBLED data] | [160 bytes of spare/ecc | 2048 bytes SCRAMBLED data] | [160 bytes of spare/ecc | 2048 bytes SCRAMBLED data]

and the PC3000 descrambled data is just 8192 bytes of data with no spare area data, could we split each page the PC3000 descrambled data into 4x 2048 byte chunks, prepend the 160 bytes of spare/ecc from the raw dump and reconstruct a page structure looking like

[160 bytes of spare/ecc | 2048 bytes DE-SCRAMBLED data] | [160 bytes of spare/ecc | 2048 bytes DE-SCRAMBLED data] | [160 bytes of spare/ecc | 2048 bytes DE-SCRAMBLED data] | [160 bytes of spare/ecc | 2048 bytes DE-SCRAMBLED data]

and then work our way from this?


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 Post subject: Re: Question regarding settings
PostPosted: August 11th, 2022, 10:28 
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Joined: June 11th, 2013, 17:01
Posts: 1710
Location: Phoenix, AZ USA
Isn't that SSD encrypted?

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 Post subject: Re: Question regarding settings
PostPosted: August 12th, 2022, 3:14 
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Joined: July 23rd, 2018, 2:19
Posts: 14
Location: north of the wall
Doesn't look like it since we're getting clear text data when using the functionality in PC3000.

Anyways, still looking for some input on the "blocks per plane" setting in PC3000.


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