--- In Eddie Dawydiuk <> wrote:
>>
This utility should not be used to periodically repair
bad blocks, if you are getting large amounts of bad blocks(>1-2%) then there is
more than likely a bug somewhere or your writing huge amounts of data to Nand
flash at a very fast rate(IIRC a 2KB block is guaranteed good for 10K writes).
If you are truly getting bad blocks because they have been worn out, then you
should not attempt to recover these blocks as they are truly bad and will lose
data in the future.
>>
many thanks for all your detailed comments on your experiences with this
problem.
I originally replied to another thread about 6m ago about very long mounting
delays on yaffs2. My TS7250 2kNAND board was taking over 90s to mount.
I would now be fairly sure that this is a precursor to the "tragic" failure I
am now seeing.
I should point out that this board is still running an original ts 2.4 kernel
(-ts12) , reading some of the threads on aleph1's site that I found googling
this issue there have been several problems in this area , one of which was
apparently adressed in an update only a few months ago. (june2009 from memory).
There are some circumstances in the use of this board that may bring out the
bug.
Occasional brown-outs that causes the 7250 to reboot.
During testing , some abrupt power offs.
True flash wear? Well all logging is off and most of the data logging done on
the board is done to a ram disk. The data file is copied to flash once per
hour, size is from 0 to 50kB, an day long average of 30k would mean 15 blocks.
A rough calculation makes that 128,000 block.writes/year. If yaffs2 is doing
the load spreading that is it's primary function, that means each of the 64,000
2k blocks gets written twice per year.
Current flash occupancy from du is 44MB (34%). There are no more free erase
blocks!
If yaffs has been taking out good blocks as it seems , the few remaining blocks
will likely have suffered true burn out recently.
In view of the other poster , Gary, in the yaffs tragedy thread:
http://tech.groups.yahoo.com/group/ts-7000/message/15589 who has three of these
boards u/s with this problem and the significant number of returns you have on
this , I'd say there is a real issue that needs thorough investigation here.
In fact any further posts on this subject should probably go there rather than
here. "where's the source?" has now been answered.
If you could look at that thread I am still having difficulty booting the
vmlinux.bin you supply to run this tool.
Thanks again for the detailed information on this problem.
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