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

[Charles Manning]

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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