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| docs:techref:flash [2022/01/12 10:46] – [Bad blocks] stintel | docs:techref:flash [2023/03/04 17:29] (current) – [NAND-specific tools for reading and writing to raw NAND] openwart | ||
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| Likewise nandwrite writes the image also writing the appropriate parity data for the ECC logic to work when reading it. | Likewise nandwrite writes the image also writing the appropriate parity data for the ECC logic to work when reading it. | ||
| - | The **dd** tool (or more advanced ones like **pv** is not aware of NAND ECC logic, so it will read all the NAND partition, both data AND parity and will generate a backup that is exactly the same as actually on flash, but is completely useless and unreadable as it will contain both data and hardware-specific parity information which cannot be restored on a different device. Likewise on writing, it will not write parity information for ECC logic to work, so whatever you write will be read as garbage. | + | The **dd** tool (or more advanced ones like **pv**) is not aware of NAND ECC logic, so it will read all the NAND partition, both data AND parity and will generate a backup that is exactly the same as actually on flash, but is completely useless and unreadable as it will contain both data and hardware-specific parity information which cannot be restored on a different device. Likewise on writing, it will not write parity information for ECC logic to work, so whatever you write will be read as garbage. |
| Tools like **dd** and **pv** can only be used on block devices. SSDs, SDcards, Hard drives (yes also mechanical hard drives have ECC logic integrated), | Tools like **dd** and **pv** can only be used on block devices. SSDs, SDcards, Hard drives (yes also mechanical hard drives have ECC logic integrated), | ||