Hello David,
----- Original Message -----
From: "David Greaves" <david@xxxxxxxxxxxx>
To: "Janos Haar" <djani22@xxxxxxxxxxxx>
Cc: <linux-raid@xxxxxxxxxxxxxxx>
Sent: Wednesday, May 14, 2008 12:45 PM
Subject: Re: questions about softraid limitations
Janos Haar wrote:
Hello list, Neil,
Hi Janos
I have worked on a faulty hw raid card data recovery some days before.
The project is already successfully done, but i run into some
limitations.
Firstly, are you aware that Linux SW raid will not understand disks
written by
hardware raid.
Yes, i know, but the linux raid is a great tool to try it, and if the user
know what he is doing, it is safe too. :-)
Than try to build an "old fashion" linear arrays from each disks + 64k
another blockdevice. (for store the superblock)
But the mdadm refused to _build_ the array, because the source scsi
drive is jumpered to readonly. Why? :-)
This will not allow md to write superblocks to the disks.
I think exactly for this steps:
dd if=/dev/zero of=suberblock.bin bs=64k count=1
losetup /dev/loop0 superblock.bin
blockdev --setro /dev/sda
mdadm --build -l linear /dev/md0 /dev/sda /dev/loop0
The superblock area is writable.
And this is enough to try to assemble the array to do the recovery, but this
step is refused.
I try to build the array with --readonly option, but the mdadm still
dont understand what i want. (yes, i know, rtfm...)
This will start the array in readonly mode - you've not created an array
yet
because you haven't written any superblocks...
Yes, i only want to build, not to create.
Its OK, but what about building a readonly raid 5 array for recovery
usage only? :-)
That's fine. If they are md raid disks. Yours aren't yet since you haven't
written the superblocks.
I only want to help for some people to get back the data.
I only need to build, not to create.
Thanks,
Janos Haar
David
--
To unsubscribe from this list: send the line "unsubscribe linux-raid" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
--
To unsubscribe from this list: send the line "unsubscribe linux-raid" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
