problem in unmounting and removing a volume group

sanaz · 08-20-2012, 03:26 PM

Hi all, i'm new to linux and virtualization.

I'm trying to mount an image(fedora1.img)

mount -o loop fedora1.img /mnt/img/fedora1

but i got this error:

mount: wrong fs type, bad option, bad superblock on /dev/loop2,
missing codepage or helper program, or other error
In some cases useful info is found in syslog - try
dmesg | tail or so

after that I tried(after googling):

Code:

#mount -t ext4 -o loop,ro,noload,offset=1048576 fedora1.img /mnt/img/fedora1
# fdisk -lu /etc/xen/fedora1.img

Disk /etc/xen/fedora1.img: 21.5 GB, 21474836480 bytes
255 heads, 63 sectors/track, 2610 cylinders, total 41943040 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x000697fc

               Device Boot      Start         End      Blocks   Id  System
/etc/xen/fedora1.img1   *        2048     1026047      512000   83  Linux
/etc/xen/fedora1.img2         1026048    41943039    20458496   8e  Linux LVM

# kpartx -av /etc/xen/fedora1.img

# vgscan
  Reading all physical volumes.  This may take a while...
  Found volume group "vg1" using metadata type lvm2

#vgchange -ay vg1
  3 logical volume(s) in volume group "vg1" now active

# lvs
  LV   VG   Attr     LSize   Pool Origin Data%  Move Log Copy%  Convert
  lv1  vg1  -wi-ao--  39.06g                                           
  lv2  vg1  -wi-ao-- 858.53g                                           
  lv3  vg1  -wi-ao--  33.41g 

# mount /dev/vg1/lv1 /mnt/img/fedora1/
mount: special device /dev/vg1/lv1 does not exist

But there is no file in /dev/vg1
and this content of /mnt/img/fedora1:
config-3.3.4-5.fc17.i686 efi elf-memtest86+-4.20 grub grub2 initramfs-3.3.4-5.fc17.i686.img lost+found memtest86+-4.20 System.map-3.3.4-5.fc17.i686 vmlinuz-3.3.4-5.fc17.i686

and even mknod did not work:
# mknod -m 666 /dev/vg1/lv1 b 3 1
# mknod -m 666 /dev/vg1/lv2 b 3 1
# mknod -m 666 /dev/vg1/lv3 b 3 1

But again I got another error:

# mount /dev/vg1/lv1 /mnt/img/fedora1/
mount: /dev/vg1/lv1 is not a valid block device

So I'm trying to unmount and mount again:

umount /mnt/img
umount: /mnt/img: target is busy.
(In some cases useful info about processes that use
the device is found by lsof(8) or fuser(1))

when I was trying to deactivate vg1:

#vgchange -a n vg1
Can't deactivate volume group "vg1" with 3 open logical volume(s)

and

vgchange -a n vg1
Can't deactivate volume group "vg1" with 3 open logical volume(s)

and :

lvremove /dev/vg1/lv1
Logical volume vg1/lv1 contains a filesystem in use.

and:

Code:

#vgremove vg1
Do you really want to remove volume group "vg1" containing 3 logical volumes? [y/n]: y
Do you really want to remove active logical volume lv3? [y/n]: y
  device-mapper: remove ioctl on  failed: Device or resource busy
  device-mapper: remove ioctl on  failed: Device or resource busy
  device-mapper: remove ioctl on  failed: Device or resource busy
  device-mapper: remove ioctl on  failed: Device or resource busy
  device-mapper: remove ioctl on  failed: Device or resource busy
  device-mapper: remove ioctl on  failed: Device or resource busy
  device-mapper: remove ioctl on  failed: Device or resource busy
  device-mapper: remove ioctl on  failed: Device or resource busy
  device-mapper: remove ioctl on  failed: Device or resource busy
  device-mapper: remove ioctl on  failed: Device or resource busy
  device-mapper: remove ioctl on  failed: Device or resource busy
  device-mapper: remove ioctl on  failed: Device or resource busy
  device-mapper: remove ioctl on  failed: Device or resource busy
  device-mapper: remove ioctl on  failed: Device or resource busy
  device-mapper: remove ioctl on  failed: Device or resource busy
  device-mapper: remove ioctl on  failed: Device or resource busy
  device-mapper: remove ioctl on  failed: Device or resource busy
  device-mapper: remove ioctl on  failed: Device or resource busy
  device-mapper: remove ioctl on  failed: Device or resource busy
  device-mapper: remove ioctl on  failed: Device or resource busy
  device-mapper: remove ioctl on  failed: Device or resource busy
  device-mapper: remove ioctl on  failed: Device or resource busy
  device-mapper: remove ioctl on  failed: Device or resource busy
  device-mapper: remove ioctl on  failed: Device or resource busy
  device-mapper: remove ioctl on  failed: Device or resource busy
  Unable to deactivate vg1-lv3 (253:0)
  Unable to deactivate logical volume "lv3

Now the question is how can I remove vg1?

and this is the result of:

Code:

# df -H
Filesystem                 Size  Used Avail Use% Mounted on
rootfs                      42G   21G   19G  53% /
devtmpfs                    17G     0   17G   0% /dev
tmpfs                       17G     0   17G   0% /dev/shm
tmpfs                       17G  124M   17G   1% /run
/dev/mapper/vg1-lv1         42G   21G   19G  53% /
tmpfs                       17G     0   17G   0% /sys/fs/cgroup
tmpfs                       17G     0   17G   0% /media
xenstore                    17G   82k   17G   1% /var/lib/xenstored
/dev/sda2                  521M  131M  365M  27% /boot
/dev/mapper/vg1-lv2        921G   14G  862G   2% /scratch
cs-nfs:/vol/home/grad1/    537G  204G  333G  38% /home/grad1
champ:/mnt/data5/scripts/  6.6T  3.7T  2.9T  56% /research/scripts
/dev/loop0                 921G   14G  862G   2% /mnt/img
/dev/mapper/vg1-lv1        921G   14G  862G   2% /mnt/img
/dev/mapper/vg1-lv2        921G   14G  862G   2% /mnt/img
/dev/loop1                 521M   61M  435M  13% /mnt/img/fedora1

jschiwal · 08-21-2012, 11:51 PM

The fedora.img image file is an image of a hard drive, that contains two partitions.

Code:

Device                  Boot    Start           End       Blocks          Id      System
/etc/xen/fedora1.img1   *       2048            1026047   512000          83      Linux
/etc/xen/fedora1.img2           1026048         41943039  20458496        8e      Linux   LVM

Older partition tables had the first partition start on block 63. Newer partitions start on 2048, as is the case here.

The first partition is a 25 MB /boot partition. The second on contains the LVM. To attach the LVM to a loop device, you need to add the offset:

Code:

sudo losetup -fs /etc/xen/fedora1.img2 -o $((1026048*512))

Have you tried "kpartx -d" to remove the mappings you created?

sanaz · 08-22-2012, 02:24 PM

But I only have fedora.img not fedora.img1 and fedora.img2

sKaar · 08-22-2012, 10:22 PM

maybe use full path to the image?

jschiwal · 08-22-2012, 11:48 PM

I'm saying that the image file you have contain's two partions. If you want to access the file system on either one, you need to use an offset to the beginning of partition in your losetup command. The kpartx command worked because it uses the partition table to locate the partitions inside the image.

kedarp · 08-23-2012, 12:18 AM

Post the o/p in "[code ] " and "[/code ]" tags. It make your post quite easy to read.

sanaz · 08-27-2012, 11:49 AM

Dear jschiwal:

How can I do that?

sKaar · 08-27-2012, 02:10 PM

i'm guessing, knowing where the file table starts or something will allow the other tools to figure how to mount both. iow... you were told how, a few posts up.