Remove a raid device to build a new one

ilhbutshm · 09-04-2006, 01:46 PM

Hi!

I'm trying to build a raid 1 device (md0) from /dev/sda1 and /dev/sdb1.

I've already created my raidtab file, but when I try to 'mkraid /dev/md0', I get an error. I checked the current state of raid devices with 'lsraid -p' and this is what I got:

Code:

[dev   9,   0] /dev/md0         7DEF03BE.C9EE48B1.83CDA9EC.A771EE7C offline
[dev   8,   1] /dev/sda1        7DEF03BE.C9EE48B1.83CDA9EC.A771EE7C good
[dev   ?,   ?] (unknown)        00000000.00000000.00000000.00000000 missing

How can I delete / remove / destroy these devices, so I can create them again? I suppose I can leave the /dev/sda1 device alone since it says its good, but I'd like to get rid of md0 and ?? device...

ilhbutshm · 09-04-2006, 06:01 PM

Hi

I deleted data on both disks (deleted and rewrote the partition tablesin fdisk), reinstalled LILO and Slackware 10.2.
The problem persists, here is some info:

fdisk /dev/sda

Code:

Disk /dev/sda: 200.0 GB, 200048565760 bytes
255 heads, 63 sectors/track, 24321 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1               1         262     2104483+  82  Linux swap
/dev/sda2   *         263        1046     6297480   83  Linux
/dev/sda3            1047       24321   186956437+  83  Linux

fdisk /dev/sdb

Code:

Disk /dev/sdb: 200.0 GB, 200049647616 bytes
255 heads, 63 sectors/track, 24321 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1               1         262     2104483+  82  Linux swap
/dev/sdb2             263        1046     6297480   fd  Linux raid autodetect
/dev/sdb3            1047       24321   186956437+  fd  Linux raid autodetect

lsraid -d /dev/sda1

Code:

[dev   9,   0] /dev/md0         80DA9999.519D2C8F.2E2C6CAF.A70C8899 offline
[dev   8,   1] /dev/sda1        80DA9999.519D2C8F.2E2C6CAF.A70C8899 good
[dev   ?,   ?] (unknown)        00000000.00000000.00000000.00000000 missing

I don't really know how this md0 array survived the system reinstall, but I'm guessing I have to get rid of it before I start setting up a new raid1 array.

Am I right, or am I barking at the wrong tree here?

I'd appreciate any useful info on this since I'm a newb

ilhbutshm · 09-05-2006, 05:00 AM

I got some progress now. I found out that the reason raid array 'survived' sys reinstall is that the raid metadata is written to the end of the partition, and I resized the partitions the exact same way as before...

So, to destroy a md0 array I used:

Code:

mdadm --zero-superblock /dev/sda1

But I bumped into a new problem. Not that the md0 array is gone (lsraid -p shows nothing), I try to create a new array with my /etc/raidtab and running:

Code:

mkraid -R /dev/md0

But the second disk always fails. If the first disk in the array should be /dev/sda1, then I get /dev/sdb1 Failed. And versa, if the first disk in the array should be /dev/sdb1, then I get /dev/sda1 Failed.

What to do?

edit: the partition tables are the same as the above, this is my /etc/raidtab:

Code:

raiddev			/dev/md0
raid-level		1
nr-raid-disks		2
nr-spare-disks		0
persistent-superblock	1
device			/dev/sdb1
raid-disk		0
device			/dev/sda1
failed-disk		1
chunk-size		32

raiddev			/dev/md1
raid-level		1
nr-raid-disks		2
nr-spare-disks		0
persistent-superblock	1
device			/dev/sdb2
raid-disk		0
device			/dev/sda2
failed-disk		1
chunk-size		32

raiddev			/dev/md2
raid-level		1
nr-raid-disks		2
nr-spare-disks		0
persistent-superblock	1
device			/dev/sdb3
raid-disk		0
device			/dev/sda3
failed-disk		1
chunk-size		32