RAID duplication

[mike at bilow.com (Michael Bilow)]

You would have to replicate all of the code which understands something of
the higher level of each filesystem.  It would, I think, be much better to
just mount to filesystem, possibly to some safe mount point if that is an
issue, and pull the contents of that way.  Even if you could do this
without mounting, you would have to keep your private version of all of
the kernel code which understands filesystems up to date, and this would
be a maintenance nightmare considering how frequently new versions of the
Linux kernel code are released.

You could use dd to do it, I guess, but there would certainly be
consequences and you are guaranteed that certain facilities, especially
fsck, would likely break.

-- Mike


On 2000-12-07 at 08:27 -0500, Brad Noyes wrote:

> Hi
> Thanks for replying Mike. I would like to get this to work without the 
> volumes being mounted. I'm looking to make an exact duplicate, simaler to
> how ghosting works (or as i understand it to work anyway). 
> 
> Idealy i want to make a bootable linux floppy, and have it duplicate
> arrays reguardless of OS and filesystem on the array. So i'm not sure if
> this is even possible. Any thoughts?
> 
> Thanks,
> --Brad 
> 
> 
> On Thu, Dec 07, 2000 at 03:52:54AM -0500, Michael Bilow wrote:
> > As a mounted volume?  Why not just use tar?
> > 
> > 	tar -cpf - -c /vol1 . | tar -xpf - -c /vol2
> > 
> > I'm not contending that this exact syntax will work -- I just dashed it
> > off now without testing it -- but it should illustrate the concept.
> > 
> > You cannot really use dd to copy an exact disk array because most
> > filesystems (including second extended) precomute the locations of the
> > spare superblocks based upon the logical media size.  If you use dd, then
> > you will mess this up and things like ext2fs can fail, even if you do
> > manage to get a mountable volume.
> > 
> > -- Mike
> > 
> > 
> > On 2000-12-06 at 16:22 -0500, Brad Noyes wrote:
> > 
> > > Hi Guys,
> > > I'm trying to find a way to duplicate a RAID 5 array. I'm using the compaq 3200 smart array controller. I can setup 2 arrays on the machine, and i'm
> > > looking to copy one to the other, to duplicate the array. Has anyone tried this, or know one way or another if this is possible, or have any
> > > suggestions on doing this (i was thinking dd)?
> > > 
> > > Thanks,
> > > --Brad

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