Hello list, Neil,
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.
For the best safe way first i have jumperd the drives to readonly mode.
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? :-)
I try to build the array with --readonly option, but the mdadm still dont
understand what i want. (yes, i know, rtfm...)
The next step is:
mdadm --create --assume-clean -l 5 /dev/mdX --raid-disks 5 /dev/....
(And this step is refused too if the drives or some part of the sources are
readonly.)
Its OK, but what about building a readonly raid 5 array for recovery usage
only? :-)
And _build_ a degraded-readonly raid 4-5-6 is even better if this will ever
available....
And i need to set the readonly flag _after_ the --create, but the --create
+ --assume-clean is logical, and working combination with --readonly.
More additionally, i think the only write the superblocks to the disks, when
the --readonly flag is cleared.
And more, if the readonly raid 4-5-6 array can handle, and recover the bad
sectors from the parity infos.... hmmmm... :-)
These little options can be great help for data recovery, and all is safe.
Thanks and regards,
Janos Haar
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