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A NILFS2 score cardA NILFS2 score cardPosted Nov 7, 2012 14:41 UTC (Wed) by hmh (subscriber, #3838)In reply to: A NILFS2 score card by mirabilos Parent article: A NILFS2 score card
Writing to a FLASH-like device means transitioning bits from 1 to 0 or leaving them unchanged. Erasing a FLASH-like device transitions all bits to 1.
So, a page full of 0xff is ready for writing. One full of 0x00 has to be erased to receive any other data. Only, you must erase a full block at a time, and blocks are (much) larger than pages.
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A NILFS2 score card Posted Nov 7, 2012 18:46 UTC (Wed) by zlynx (subscriber, #2285) [Link]
But if the hardware has a FTL you have no real idea of how the actual hardware works. You only have the view through the FTL. Reading an erased block may return 0xFF. It may return 0x00. It might return the data that was in there before the "erase" operation. It might not read from the flash hardware at all because if the FTL has a range map of free/TRIM'd/secure-erased blocks it might check the range and return a purely synthetic block.
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