topic Re: Software Raid device destruct/remove in Operating System - Linux

Software Raid device destruct/remove

Adam Garsha — Mon, 01 May 2006 09:43:34 GMT

I was playing around with raidtools/mdadm. I created a raid 1 device "/dev/md0" using two partitions (hda1,hda2).

Now, I am done playing and I want to get rid of any notion of /dev/md0. After, I plan to put hda1 and hda2 back into service as regular partitions.

If I do a "raidstop /dev/md0" and then a "lsraid -p", I see that the raid device is "offline".

How do I "rmraid /dev/md0"?... i.e. I want to erase my toying and get rid of /dev/md0... how do I do this?

Seems there are plenty of docs for building a raid set (Suse 9.3), but nothing about how to undo/remove your raid sets once you've decided that you don't want to use software raid.

Re: Software Raid device destruct/remove

Steven E. Protter — Mon, 01 May 2006 13:23:04 GMT

Shalom Adam,

You can use the tools to break the raid, then rmsf should remove the device. If not, you may have to live with it sitting out there. It won't do anything.

SEP

Re: Software Raid device destruct/remove

Matti_Kurkela — Tue, 02 May 2006 02:29:19 GMT

(SEP: you gave a HPUX answer to a Linux question... :-)

When you created the RAID1 device, you probably set the partition type of /dev/hda1 and /dev/hda2 to 0xfd (Linux raid autodetect), right?

When the RAID1 device is offline, you can use fdisk to modify the partition type of /dev/hda1 and /dev/hda2 to any value you prefer. Then you can mkfs the partition(s) if necessary. After that they will no longer be detected as RAID at next reboot.

If you have the RAID1 functionality as a kernel module and all software RAID1 devices are offline, you can make the system forget the RAID1 device without a reboot by just unloading the kernel module:
rmmod raid1
If your kernel has RAID1 functionality statically built in (not as a module), you cannot do that. In that case, booting is unavoidable.

There is also mdadm -r (remove) command, which might help. The "raidstart/raidstop" commands are the old way of handling software RAID on Linux, while "mdadm" is the new way. If your distribution is old enough to have the raid* commands, it might not have the newest mdadm with all the options.

Re: Software Raid device destruct/remove

Adam Garsha — Tue, 02 May 2006 08:40:14 GMT

Matt nailed it.