Linux-kernel mailing list archive 2000-15,: Re: EXT2 and BadBlock updating.....

# Re: EXT2 and BadBlock updating.....

Ed Carp (erc@pobox.com)
Thu, 13 Apr 2000 09:18:09 -0500

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Stephen C. Tweedie (sct@redhat.com) writes:

> > The problem with this approach is, if you're working with systems that are up 24x7, to *not* have the ability to automatically detect a bad block, copy the data to another block, then mark that block as bad is a real pain at best and completely unacceptable at worst. One of my clients is using Linux in a network communications controller (SONET/ATM backplane) and this sort of thing is going to raise the pain level around here as soon as someone realizes that badblocks aren't taken case of.

> Huh? Modern disks do this for you anyway. It is counterproductive
> for the kernel to try to help, because if the kernel remaps what appears
> to be a bad block, then you're just duplicating effort. The next time
> the kernel tries to write to that "bad" block, the disk will have
> remapped it on its own.

Most modern disks do this for you *transparently* - the driver doesn't even
see the error, so this does't really apply. If the kernel sees an error, it's
a real error, as opposed to one that has been remapped.

> And if you exhaust the size of the disk's remapping tables, you are
> in big trouble because your disk is on its way to the big data center
> in the sky.

Not entirely true in all cases - I've got drives that develop a bad block or
two every year or so, and they've been in service for at least 3 years.
Perhaps I've got one of those drives that doesn't do the remapping for me.

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- Maybe in reply to: Andre Hedrick: "EXT2 and BadBlock updating....."
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