Re: Unable to mount loopback devices in RAID mode

[Andi Drebes <lists-receive@programmierforen.de>]

Hi!

> So I do not understand why it does not work correctly for
> him to mount either device.  Maybe this problem is not
> what I see in my testing (using 32) with disk partitions
> instead of loop.
>=20
> With partitions, I only see the mount problem on raid0,
> not on raid1.
Without having looked at the code:
It seems as if this is a problem in mkfs. The first time, I mount the f=
resh image I have to search the correct device. After having mounted it=
 at least once, I can use both devices interchangeably:

$ dd if=3D/dev/zero of=3Draid1_0.img bs=3D1M count=3D500
$ dd if=3D/dev/zero of=3Draid1_1.img bs=3D1M count=3D500
$ mkfs.btrfs -m raid1 -d raid1 raid1_0.img raid1_1.img
$ losetup /dev/loop0 raid1_0.img
$ losetup /dev/loop1 raid1_1.img
$ mount -t btrfs /dev/loop0 /mnt/btrfs
mount: wrong fs type, bad option, bad superblock on /dev/loop0,
=A0 =A0 =A0 =A0missing codepage or helper program, or other error
=A0 =A0 =A0 =A0In some cases useful info is found in syslog - try
=A0 =A0 =A0 =A0dmesg | tail =A0or so
$ mount -t btrfs /dev/loop1 /mnt/btrfs
#OK
$ umount /mnt/btrfs
$ mount -t btrfs -o ro /dev/loop0 /mnt/btrfs
#OK
$ umount /mnt/btrfs
$ mount -t btrfs -o ro /dev/loop1 /mnt/btrfs
#OK

So my guess is, that there's something wrong with mkfs.

	Cheers,
		Andi
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