Re: [gentoo-user] defect management block device

[Alan McKinnon <alan.mckinnon@gmail.com>]

On Monday 24 March 2008, Enrico Weigelt wrote:
> Hi folks,
>
>
> does anyone know an (virtual) block device which can do automatic
> defect management (if the underlying disks have badblocks) ?
>
> My idea goes like this:
> * one or more devices are assigned to one block device
> * a bunch of spare blocks are reserved for defect management
>   (so the device looks smaller than the sum of assigned disks)
> * if an badblock is detected, it's automatically remapped
>   to an spare block
>
> In fact, just what drive-internal defect manangement does, but
> at OS / driver level.

I don't see the point, unless you are dealing with drives that do not 
have defect management.

What makes you think you can accomplish this result better than the 
firmware on the drive? It seems to me that if the drive firmware missed 
the opportunity to relocate the bad block, then your window of 
opportunity to do it in your code has long since passed. IOW, the OS 
code cannot possibly ever achieve it's design result.

Just a thought, maybe you know some aspect of disks that I don't and can 
see where this would be useful. From where I sit, I can;t see any such 
use-case.


-- 
Alan McKinnon
alan dot mckinnon at gmail dot com

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