Possible to delete RAID metadata from hard drives?

[Howard Griffin]

Is there any way to remove/delete/deactivate RAID metadata (aka
"signatures") from my hard drives? A long time ago I had the drives in
a RAID set, but quickly reconsidered and decided to use them as
independent drives. My disaster-recovery CD (for restoration of a
disk image) boots into SuSE Linux (with DMRAID) and insists on seeing
the two drives as a RAID set because of the metadata present on them.
Thus, the disaster-recovery CD is useless. I want to remove the
metadata from these drives so the recovery CD will see them as
separate drives. I have gone into the SATA/RAID BIOS for my Silicon
Image 3112 controller, but it reports that no RAID sets exist and that
there are no conflicts to resolve. Can anyone advise? Would the
DMRAID tool allow me to deactivate the metadata? Many thanks.

 

[Arno Wagner]

Is there any way to remove/delete/deactivate RAID metadata (aka
"signatures") from my hard drives? A long time ago I had the drives in
a RAID set, but quickly reconsidered and decided to use them as
independent drives. My disaster-recovery CD (for restoration of a
disk image) boots into SuSE Linux (with DMRAID) and insists on seeing
the two drives as a RAID set because of the metadata present on them.
Thus, the disaster-recovery CD is useless. I want to remove the
metadata from these drives so the recovery CD will see them as
separate drives. I have gone into the SATA/RAID BIOS for my Silicon
Image 3112 controller, but it reports that no RAID sets exist and that
there are no conflicts to resolve. Can anyone advise? Would the
DMRAID tool allow me to deactivate the metadata? Many thanks.

Complete disk/parition blanking under Linux:

cat /dev/zero > /dev/hd<target> (or /dev/sd<target> for SCSI/SATA)

or with comfortable progress output

dd_rescue -w /dev/zero /dev/hd<target> (see above)

This will remove any data from the drive, including the
matadata. If this is Linux software RAID, you can speed things
up by overwtriting only the last MBs of the raid devices
(drive or partition), since the dm stores the RAID superblock
there. Use option -S <size - 100MB, e.g.> of dd_rescue. I don't
know whether SuSe has dd_rescue, but Knoppix does.

Arno

 

[Howard Griffin]

So, I guess there's no way to do this non-destructively, correct?

 

[Rod Speed]

Is there any way to remove/delete/deactivate RAID metadata (aka
"signatures") from my hard drives? A long time ago I had the drives
in a RAID set, but quickly reconsidered and decided to use them as
independent drives. My disaster-recovery CD (for restoration of a
disk image) boots into SuSE Linux (with DMRAID) and insists on seeing
the two drives as a RAID set because of the metadata present on them.
Thus, the disaster-recovery CD is useless. I want to remove the
metadata from these drives so the recovery CD will see them as
separate drives. I have gone into the SATA/RAID BIOS for my Silicon
Image 3112 controller, but it reports that no RAID sets exist and that
there are no conflicts to resolve. Can anyone advise? Would the
DMRAID tool allow me to deactivate the metadata? Many thanks.

You can always wipe the drives with something like clearhdd from
http://www.samsung.com/Products/HardDiskDrive/utilities/clearhdd.htm

That writes zeros thru every sector on the drive, so no data survives that.

 

[Arno Wagner]

So, I guess there's no way to do this non-destructively, correct?

Oh, you want to do it nondestructively. Sotty, missed that.
There is. But you need to calculate the position of the
metadata block right and give the correct offset to dd_rescue.
Better avoid that, since it is likely to go wrong on the first
attempt.

You can mount the disks individually by first breaking
the RAID set. Depending on the version of the RAID tools
you have, ''raidstop'' or ''mdadm'' with some option is
what you are looking for. As soon as the raid is stopped,
you can use an ordinary mount to mount the individual
disks or paritions. The next autodetect will assemble the
RAID though.

Another thing that may prevent autodetection is setting the
partition type back from "fb" (raid autodetect) to "82"
(or was it "83"? Don't remember, but is marks an ordinary
Linux parition). This only prevents auto-start/assembly by
the kernel, not by some additonal scripts your partition
may have.

Arno

 

[Arno Wagner]

Oh, you want to do it nondestructively. Sotty, missed that.
There is. But you need to calculate the position of the
metadata block right and give the correct offset to dd_rescue.
Better avoid that, since it is likely to go wrong on the first
attempt.

You can mount the disks individually by first breaking
the RAID set. Depending on the version of the RAID tools
you have, ''raidstop'' or ''mdadm'' with some option is
what you are looking for. As soon as the raid is stopped,
you can use an ordinary mount to mount the individual
disks or paritions. The next autodetect will assemble the
RAID though.

Another thing that may prevent autodetection is setting the
partition type back from "fb" (raid autodetect) to "82"
(or was it "83"? Don't remember, but is marks an ordinary
Linux parition). This only prevents auto-start/assembly by
the kernel, not by some additonal scripts your partition
may have.

I just had a look at the madam man-page. It seems deleting
the metadata is as easy as a
"mdadm --zero-superblock <disk/partition>".
Of course you have to stop the RAID array the disk/partition is
part of first. "mdadm --stop /dev/md<device>" should do that.

Sorry for not spotting this first, I am still a novice user
of the new mdadm tool.

Arno

 

[Mike Tomlinson]

Another thing that may prevent autodetection is setting the
partition type back from "fb" (raid autodetect)

0xfd, actually.

to "82"
(or was it "83"?

83. 82 is Linux swap.

 

[Arno Wagner]

0xfd, actually.

83. 82 is Linux swap.

Yes. I allways have to look it up. Fortunately fdisk has the
table build in.

Arno