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-   -   preserving old /dev/md0 - mdadm problem with --create/--assemble (http://www.linuxquestions.org/questions/linux-kernel-70/preserving-old-dev-md0-mdadm-problem-with-create-assemble-518596/)

tiainte 01-12-2007 05:15 AM

preserving old /dev/md0 - mdadm problem with --create/--assemble
 
Hardware:

/dev/hda blew up, so root FS gone and fresh install, and i'd really like to keep stuff from /dev/md0.
/dev/md0 used to be /dev/hdh + /dev/hdg on raid 1 on earlier system where /dev/hda blew up.

Situation:

Ran Ubuntu 6.10 Desktop CD,
tried to move files from forementioned hdh+hgd raid1 to new disk /dev/sda1 to use hdh+hdg as / in future.

apt-get install mdadm, as it wasnt on live cd otherwise
accidentally typed "mdadm --create /dev/md0 --level=1 --raid-disks=2 /dev/hdh1 /dev/hdg1"

Problem is that create - it should have been --assemble
I noticed my error at about 14% of re-syncing of raid, and didnt dare to stop it.
I let it run to 100% and it completed succesfully.

Mount doesnt work, it gives :
mount -t ext3 /dev/md0 /tmp/test
mount: wrong fs type, bad option, bad superblock on /dev/md0,
missing codepage or other error

mdadm says superblock is persistent.

On other hand /dev/hde1 is a single, primary partition with ext3 and it hasnt been altered in anyway way, and i cannot mount that either for some weird reason. Gives the same error as above.

I _think_ i did hdh1 and hdg1 as FD-partitions and i would very much like to get data out from them

Next thing i'm planning to do is do a fresh install to /dev/sdb - install proper kernels etc and start examining situation more closely without booting from livecd any more.

Main objective - to get as much stuff as possible from hdh/hdg out to any other device

Any help, suggestions and precautions you have in mind - please donate ;)

minuo 03-09-2007 11:27 AM

tiainte,

Have you gotten anywhere with this? I find myself in a very similar situation and thus far your post is the closest I've found via google.

If you or anyone has tips on recovering from an accidental --create I would be most appreciative!

--minuo

tiainte 03-11-2007 06:58 AM

Quote:

Originally Posted by minuo
tiainte,

Have you gotten anywhere with this? I find myself in a very similar situation and thus far your post is the closest I've found via google.

If you or anyone has tips on recovering from an accidental --create I would be most appreciative!

--minuo

Actually - i got every single bit of data out from there, and the rebuild went nicely trough with all the data intact.

Lesson learned:
Do not, DO NOT, use any kind of craplivecd's to do any kind of examinations, they usually lack something really relevant like mdadm, smbfs or maybe even cfdisk. Most of the problems i had were because of that crapbuntu liveCD that didnt have all the stuff i needed. Mounting problems were gone that instant i booted with new-enough kernel with all the tools i needed.

In my case, accidental --create didnt create or destroy anything, it just "rebuilt" something. I did fresh install to new /dev/hda - installed everything needed, and rebooted. Then mounted /dev/md0 and voilá - data was there.

Now i have "ghost" /dev/md2 with /dev/hdh (NOT /dev/hdh1) which delays my boot times, but that's a minor nuisance ;)
/dev/md0 and /dev/md1 are working nice & smooth atm.


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