I know a guy that rebuilt a hw raid5 array by hand after the controller bit
the dust.  Well, he wrote some C code to go in and figure out the stripe size,
then piece it all back together. 

But his drives were all good.

He's going to have to send the drives off for recovery, then piece the stripes
back together.  Not going to be a lot of fun.

Why was important data being stored on a RAID-0 array?


Craig White spoke forth with the blessed manuscript:
> On Sun, 2006-03-26 at 20:40 -0700, Technomage wrote:
> > On Sunday 26 March 2006 20:18, Nathan England wrote:
> > > The problem with raid 0, while giving expanded filesystems over many disks
> > > is there is no fault tolerance, so it is possible that when one of those
> > > drives took a dump, you lost ALL of that data. I could be wrong, but I'm
> > > pretty sure that is how it works.
> > > Does the drive power up at all?
> > yes
> > 
> > > Or is it completely dead? 
> > > What is the file system on it? Can you boot with a knoppix disc and try to
> > > let it e2fsck or reiserfsck that filesystem and see if it fixes it?
> > 
> > fs = XFS
> > 
> > problem is: the drive is not mountable (given previously stated errors) even 
> > in a live or rescue configuration.
> > 
> > now, I am running a test of this given that a friend of mine has this 
> > identical problem, only he has FORENSIC DATA stored on there and he 
> > ABSOLUTELY NEEDS TO RECOVER IT and thus, he is unwilling to try these tests 
> > on his disks due to lack of hardware backups (more disks).
> > 
> > this means, I need some way of recovering the data from the first of 2 discs 
> > given that the second one in the raid 0 configuration is either failed 
> > (hardware) or otherwise not usable.
> > 
> > 
> > >
> > > On Sunday 26 March 2006 20:13, Technomage wrote:
> > > > I need the help of a raid "expert"
> > > >
> > > > I have a raid 0 problem. seems that when a machine went belly up on me,
> > > > it damages part of a raid 0 virtual fs in such a way that I can no longer
> > > > mount the 2nd 9and smaller) half of the filesystem.
> > > >
> > > > the kernel panics on boot and I get all kinds of "bad magic" errors when
> > > > attempting to do so.
> > > >
> > > > I have more than enough HD space to copy the images, but I need to get
> > > > the data off this "raid 0 fs" as soon as possible.
> > > >
> > > > can anyone help?
> -------
> xfs has specific recovery tools and the normal fsck tools will simply
> destroy data. Probably a good idea to get cozy with the version of XFS
> that you are running and the file system repair tools suitable for that
> version. Perhaps you want to locate a suitable forum/mail list at SGI
> for this.
> 
> this link pretty much tells the story about RAID 0
> 
> http://www.pcguide.com/ref/hdd/perf/raid/levels/singleLevel0-c.html
> 
> from which I quote..."Special Considerations: Using a RAID 0 array
> without backing up any changes made to its data at least daily is a loud
> statement that that data is not important to you."
> 
> If you have to ask this list to suggest ways how this might be
> accomplished, you are wasting your time.
> 
> If you actually can recover data from a RAID 0 array with a dead member,
> you can probably make a fortune.
> 
> Craig
> 
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