[Yaffs] [Yaffs-archive] Re: bad block problem

On Friday 16 April 2004 16:51, Skumar wrote:
> Hi,
> i want to know on what condition will yaffs mark a block bad?
> my assumption is when it does a page read & compares the ecc calculated &
> the ecc stored in oob
> and if it does not match it marks the blcok bad. is this correct
>
> will yaffs do write verify(ie will it read back the page after write and
> check for ecc)?

There are two ways that yaffs will mark a block bad:

1). Write fails or write verify fails
After a write, the data is verified with out using ECC (ie. it muust be
written perfectly). If this fails, then the block will be retired.
2) If an ECC failure occurs on readback then the block is deemed to be
unreliable and is marked for retirement.

Retirement means that when the block gets garbage collected, instead of
reusing the block it is marked bad and is not reused.

-- Charles

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