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From: Eric Martin <freak4uxxx@gmail.com>
To: gentoo-user@lists.gentoo.org
Subject: Re: [gentoo-user] defect management block device
Date: Mon, 24 Mar 2008 14:23:29 -0400	[thread overview]
Message-ID: <47E7F1A1.8090608@gmail.com> (raw)
In-Reply-To: <200803241758.14792.alan.mckinnon@gmail.com>

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
-- 
gentoo-user@lists.gentoo.org mailing list



  reply	other threads:[~2008-03-24 18:24 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-03-24 14:32 [gentoo-user] defect management block device Enrico Weigelt
2008-03-24 15:58 ` Alan McKinnon
2008-03-24 18:23   ` Eric Martin [this message]
2008-03-24 20:47     ` Alan McKinnon
2008-03-25  1:48       ` Enrico Weigelt
2008-03-25  8:56         ` Alan McKinnon

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