On 11/2/2011 11:18 PM, Sanjana wrote:

[root@bladelinux01 ~]# mount /dev/loop0 /mnt/
mount: /dev/loop0 already mounted or /mnt/ busy
[root@bladelinux01 ~]# mount /dev/loop1 /mnt/
mount: /dev/loop1 already mounted or /mnt/ busy

But if I remove the dm device created and try to mount the underlying
block-device, I can mount both the device which took part in mirroring and
I can access the data in both the disk.
[root@bladelinux01 ~]# dmsetup remove raid1
[root@bladelinux01 ~]# mount /dev/loop0 /mnt/
[root@bladelinux01 ~]# ls -l /mnt/
total 51
drwx------. 2 root root 12288 Nov 2 22:32 lost+found
-rw-------. 1 root root 37417 Nov 2 22:38 messages

[root@bladelinux01 ~]# umount /mnt/
[root@bladelinux01 ~]# mount /dev/loop1 /mnt/
[root@bladelinux01 ~]# ls -l /mnt/
total 51
drwx------. 2 root root 12288 Nov 2 22:32 lost+found
-rw-------. 1 root root 37417 Nov 2 22:38 messages

Why is this behavior. any explanation, please....


Simple; the loop devices are still open by device-mapper, so mount is
telling you they are busy. Just because the raid device has zero opens
does not mean that it closes the underlying devices.


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