raid 0 problems

[Nathan England]

I don't want to harass any one for using a raid-0. I remember the first raid I 
built was a mirrored raid-0... Later I found out the web site I had read 
about was wrong and it wasn't a mirrored array. I quickly fixed it. Sometimes 
you need lots of space, but can't afford to do it the right way...



On Sunday 26 March 2006 21:00, Mike Garfias wrote:
> 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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