raidtools to mdadm
ok so i am trying to recover some data for a friend. what i am wanting to do is forcibly set up /dev/mdN to be a raid0 of /dev/sda and /dev/sdb
i do not want to actually change any of the contents of these drives, just mount very simply as a raid0. the raid was originally created using an onboard nvidia raid on the motherboard these drives used to be hooked to. my friend thought he could shove them into another windows box (that is what he was running on them) and have windows recover the raid. all this did was totally destroy the superblock on one of the two drives. dmraid now wont see them as a matched pair so that is out. the actual data areas of both drives seems to be intact, but unless i can get them into raid0 i dont know how i can recover the data. it figures he gives me the drives after he makes it a notch or two more of a pain :\
now before the advent of mdadm i would use /etc/raidtab and have no issues setting up the raid device.
as best i can tell i am using the correct commands for what i want but i pretty much get nothing but errors:
root@Knoppix:/media# mdadm --build /dev/md1 --chunk=128 --level=0 --raid-devices=2 /dev/sda /dev/sdb mdadm: error opening /dev/md1: No such device or address root@Knoppix:/media# mdadm --build -n 2 -c 128 -l 0 /dev/md1 /dev/sda /dev/sdb mdadm: error opening /dev/md1: No such device or address
when i run those commands i do get /dev/mdN entries created, but they do not point to a valid block device (as tested with fdisk -l and with dmraid -b)
for the life of me i dont understand why anyone would put important data on a raid0, but that is what happened in this case.
If i have to i will drop down to an older knoppix release to get raidtools back, as i have never had any issues in recovering crap onboard raid arrays nor windows software raid arrays under it. i am sure it can be done with mdadm but for the life of me i cannot seem to figure out exactly how.
any help on this would be greatly appreciated
Casey
Quoted 6 lines · On Sunday April 1, [email protected] wrote:
as best i can tell i am using the correct commands for what i want but i pretty much get nothing but errors:
root@Knoppix:/media# mdadm --build /dev/md1 --chunk=128 --level=0 --raid-devices=2 /dev/sda /dev/sdb mdadm: error opening /dev/md1: No such device or address
"No such device or address" probably means that the md module is not loaded.
modprobe md
or
modprobe md_mod
and try again.
NeilBrown
Quoted 4 lines · Casey Boone
ok so i am trying to recover some data for a friend. what i am wanting to do is forcibly set up
/dev/mdNto be a raid0 of/dev/sdaand/dev/sdbi do not want to actually change any of the contents of these drives, just mount very simply as a raid0. the raid was originally created using an onboard nvidia raid on the motherboard these drives used to be hooked to. my friend thought he could shove them into another windows box (that is what he was running on them) and have windows recover the raid. all this did was totally destroy the superblock on one of the two drives. dmraid now wont see them as a matched pair so that is out. the actual data areas of both drives seems to be intact, but unless i can get them into raid0 i dont know how i can recover the data. it figures he gives me the drives after he makes it a notch or two more of a pain :\
I have friends like that too. ;-)
Quoted 2 lines
now before the advent of mdadm i would use
/etc/raidtaband have no issues setting up the raid device. \
I haven't used raidtools for ages, but can't you bring yourself to using them now? I seem to remember that there was no superblock to be written in a bad place, which might be an advantage. mdadm has several versions which write the superblock in various places on the drives, and you may want "none of the above."
Alternatively, if these are fairly small, write a tiny program to open both physical devices, read a chunk from one, then the other, repeat while writing to something not hosed.
Quoted 22 lines
as best i can tell i am using the correct commands for what i want but i pretty much get nothing but errors:
root@Knoppix:/media# mdadm --build /dev/md1 --chunk=128 --level=0 --raid-devices=2 /dev/sda /dev/sdb mdadm: error opening /dev/md1: No such device or address root@Knoppix:/media# mdadm --build -n 2 -c 128 -l 0 /dev/md1 /dev/sda /dev/sdb mdadm: error opening /dev/md1: No such device or addresswhen i run those commands i do get
/dev/mdNentries created, but they do not point to a valid block device (as tested with fdisk -l and with dmraid -b)for the life of me i dont understand why anyone would put important data on a raid0, but that is what happened in this case.
If i have to i will drop down to an older knoppix release to get raidtools back, as i have never had any issues in recovering crap onboard raid arrays nor windows software raid arrays under it. i am sure it can be done with mdadm but for the life of me i cannot seem to figure out exactly how.
any help on this would be greatly appreciated
Casey
Signature · 3 lines
bill davidsen <[email protected]> CTO TMR Associates, Inc Doing interesting things with small computers since 1979
Quoted 5 lines
Quoted 3 lines
i do not want to actually change any of the contents of these drives, just mount very simply as a raid0. the raid was originally created using an onboard nvidia raid on the motherboard these drives used to be hooked to. my friend thought he could shove them into another windows box (that is what he was running on them) and have windows recover the raid. all this did was totally destroy the superblock on one of the two drives. dmraid now wont see them as a matched pair so that is out. the actual data areas of both drives seems to be intact, but unless i can get them into raid0 i dont know how i can recover the data. it figures he gives me the drives after he makes it a notch or two more of a pain :\
I have friends like that too. ;-)
gotta love 'em
wish i was getting paid for this one
Quoted 6 lines
Quoted 2 lines
now before the advent of mdadm i would use
/etc/raidtaband have no issues setting up the raid device. \I haven't used raidtools for ages, but can't you bring yourself to using them now? I seem to remember that there was no superblock to be written in a bad place, which might be an advantage. mdadm has several versions which write the superblock in various places on the drives, and you may want "none of the above."
Alternatively, if these are fairly small, write a tiny program to open both physical devices, read a chunk from one, then the other, repeat while writing to something not hosed.
at the suggestion of another on the list (thanks neil brown!) i tried modprobing a slew of things related to the disk mapper to no avail, then i gave up using knoppix and tried with a fedora 6 box (after i dd-ed the drives off to a larger drive) and it worked great. i can definitely say that while mdadm is quite foreign territory for me, i love the fact i can specify everything i want to happen on one command line.
btw once i actually did get the drives raided it turns out that while the partition table was intact, somehow the partition itself was fubarred enough that i couldnt mount it to save my life. finally just told the guy "you screwed it by trying to recover it, next time bring me the drives the MOMENT you have a problem"
Casey