Alan McKinnon wrote:
On Monday 24 March 2008, Enrico Weigelt wrote:
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.
While I see what Alan is saying, I'm pretty sure LVM does it. Device
Drivers -> Multiple Devices Driver Support -> Bad Block Relocation
Device Target. I've never played with it but I assume there's a lot of
good reading on it.
--
HTH, Eric
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