Date: Tue, 7 Feb 2006 17:45:12 -0500
From: Wakko Warner <wakko@animx.eu.org>
To: Phillip Susi <psusi@cfl.rr.com>
Cc: Helge Hafting <helge.hafting@aitel.hist.no>,
       alex-lists-linux-kernel@yuriev.com, linux-kernel@vger.kernel.org
Subject: Re: non-fakeraid controllers
Message-ID: <20060207224512.GB17798@animx.eu.org>
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	Helge Hafting <helge.hafting@aitel.hist.no>,
	alex-lists-linux-kernel@yuriev.com, linux-kernel@vger.kernel.org
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Phillip Susi wrote:
> Wakko Warner wrote:
> >I've been wondering about dmraid.  I considered buying an adaptec sata raid
> >(hardware).  One of the drawbacks on hardware raid is the format isn't
> >compatible with any other card (or rather manufacturer).  So the question
> >is, has anyone written anything that can detect and activate disks from a
> >hardware raid controller when they are placed on a controller w/o any raid?
> >
> >basically what I mean is, 3 disks, raid5 was in a system with hardware 
> >raid. the raid card blows up and cannot get another one so to get the data 
> >back,
> >place disks in another machine or on a standard controller and use software
> >raid or whatever to recover the data.
> 
> Yes, that is one of the problems with hardware raid controllers.  If you 
> can figure out the controller's metadata format, possibly by asking 
> adaptec, or reverse engineering, then patching dmraid to understand that 
> format ( it already understands several used by fakeraid controllers ) 
> should be rather easy. 

One of the things that I noticed with adaptec's and ami's raid (and an old mylex
dac960 IIRC) is that you can create containers or partitions (which every
they call them) on a disk set.  I guess you can take 3 disks, create a raid5
using half the capcity of the 3 disks and a raid0 on the rest.  I'm not sure
about fakeraid controllers as I've never configured one.

-- 
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