How to add files or directories to the

-img

created raw disk file. For example. I use

qemu-img create -f raw disk.raw 1G

to generate a

.raw

file. I want to copy some

/bin

,

/usr

directories to the

.raw

file. I have tried the following commands. With the reference to here

qemu-img create -f raw disk.raw 1G
mkdir /image
losetup /dev/loop0 disk.raw
fdisk /dev/loop0
    > n
    > p
    > ENTER
    > ENTER
    > ENTER
    > a
    > w
kpartx -a /dev/loop0
mount /dev/mapper/loop0p1 /image

However, the last commands output the following error messages:

: /image: wrong fs type, bad option, bad superblock on /dev/mapper/loop0p1, missing codepage or helper program, or other error.

This seems to be a problem regarding the sector size of the mapped device for a logical volume between different machines. More specifically, I'd like to know if and how the sector size of a mapped device corresponding to a logical volume can be configured. Here is a description of the problem, comparing two machines. ## Machine 1 I have an entire disk image in a logical volume mytestlv in a volume group named MyVolumeGroup. This disk image has its own partition table (completely independent of the actual disk it's stored on). For example, fdisk /dev/mapper/MyVolumeGroup-mytestlv shows this:

Disk /dev/mapper/MyVolumeGroup-mytestlv: 30 GiB, 32212254720 bytes, 62914560 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: gpt
Disk identifier: ...

Device                                    Start      End  Sectors Size Type
/dev/mapper/MyVolumeGroup-mytestlv-part1    2048     4095     2048   1M BIOS boot
/dev/mapper/MyVolumeGroup-mytestlv-part2    4096  4198399  4194304   2G Linux swap
/dev/mapper/MyVolumeGroup-mytestlv-part3 4198400 62914526 58716127  28G Linux filesystem

If I need access to the data on a partition of that disk image, I can use kpartx and mount the partition. kpartx -a /dev/mapper/MyVolumeGroup-mytestlv creates these devices files, which can be used to mount a partition within that disk image, for example:

/dev/mapper/MyVolumeGroup-mytestlvl
/dev/mapper/MyVolumeGroup-mytestlv2
/dev/mapper/MyVolumeGroup-mytestlv3

## Machine 2 This was now copied onto a different machine (content is exactly the same, checksums of both entire /dev/mapper/MyVolumeGroup-mytestlv are identical). Using the configured block size, fdisk /dev/mapper/MyVolumeGroup-mytestlv shows this:

/dev/mapper/MyVolumeGroup-mytestlv: 30 GiB, 32212254720 bytes, 7864320 sectors
Units: sectors of 1 * 4096 = 4096 bytes
Sector size (logical/physical): 4096 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: dos
Disk identifier: 0x00000000

Device                                  Boot Start     End Sectors Size Id Type
/dev/mapper/MyVolumeGroup-mytestlv-part1          1 7864319 7864319  30G ee GPT

## Differences The logical sector size is 512 on Machine 1, but 4096 on Machine 2. On Machine 1, blockdev --getss /dev/mapper/MyVolumeGroup-mytestlv returns 512. On Machine 2, blockdev --getss /dev/mapper/MyVolumeGroup-mytestlv returns 4096. ## Workaround On Machine 2, forcing the sector size to 512 with fdisk helps it see the partition table correctly.

fdisk --sector-size 512 /dev/mapper/MyVolumeGroup-mytestlv

Disk /dev/mapper/MyVolumeGroup-mytestlv: 30 GiB, 32212254720 bytes, 62914560 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: gpt
Disk identifier: ...

Device                                    Start      End  Sectors Size Type
/dev/mapper/MyVolumeGroup-mytestlv-part1    2048     4095     2048   1M BIOS boot
/dev/mapper/MyVolumeGroup-mytestlv-part2    4096  4198399  4194304   2G Linux swap
/dev/mapper/MyVolumeGroup-mytestlv-part3 4198400 62914526 58716127  28G Linux filesystem

Unfortunately, other tools such as sfdisk or kpartx don't seem to have those options. If I create a loopback device explicitly from that LV, then that loopback device has a sector size of 512, and everything works (in fact, versions of losetup that are not too old have an explicit sector size option). After losetup --show -f /dev/mapper/MyVolumeGroup-mytestlv: * blockdev --getss /dev/loop0 returns 512 * kpartx -a /dev/loop0 creates /dev/mapper/loop0p{1,2,3} ## Where is that sector size configured? I'd like to be able to use fdisk, sfdisk, kpartx without relying on an additional losetup. On Machine 2, cat /sys/block/dm-2/queue/hw_sector_size returns 4096 (/dev/mapper/MyVolumeGroup-mytestlv is actually a soft-link to /dev/dm-2). I've tried to change this using echo 512 > /sys/block/dm-2/queue/hw_sector_size, but this doesn't seem to be possible. * Is there a way to tell LVM that I'd like the sector size for the device corresponding to /dev/mapper/MyVolumeGroup-mytestlv to be 512? * Is that something that affects all the logical volumes in the group or on the system? I can't see any options with lvcreate or lvdisplay related to this.

I have an image of the mSATA SSD disk of a PC. The disk contains the operating system and has a capacity of 512GB. I do not have that free storage, so I have cloned the disk into an image with dd compressing it with gz, and later according to the answer of this post , I have copied the sparsed content so that it occupied little. This has worked correctly, resulting in a 512GB image occupying less than 5GB on disk. As a summary of what has been done:

# dd bs=64K if=/dev/sdd conv=sync,noerror status=progress | gzip -c  > /image.img.gz
# gunzip -c /image.img.gz | cp --sparse=always /dev/stdin mini.img
# ls -lhs
4,8G -rw-------  1 balon users 477G ene 13 10:54 mini.img
2,3G -rw-r--r--  1 balon users 2,3G ene 11 08:32 minimal-industrial-pc.img.gz

So far, everything is correct. The problem comes when I intend to mount the image (since I want to cage myself in it and make some changes about the file system). I have tried the following: 1. fdisk

# fdisk -l mini.img
The size mismatch of the primary master boot record (GPT PMBR) (1000215215!= 1000215295) will be corrected by writing.
The backup GPT table is not at the end of the device.
Disk mini.img: 476,94 GiB, 512110231552 bytes, 1000215296 sectors
Units: sectores de 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disc label type: gpt
Disk identifier: 74BC899D-E8BA-4C70-B82D-6F4E8F6343A3

Device    Start   End        Sectors   Size   Type
mini.img1 2048    2203647    2201600   1G     EFI System
mini.img2 2203648 6397951    4194304   2G     Linux file system
mini.img3 6397952 1000212479 993814528 473.9G Linux file system

2. kpartx

# kpartx -a -v mini.img
GPT:Primary header thinks Alt. header is not at the end of the disk.
GPT:Alternate GPT header not at the end of the disk.
GPT: Use GNU Parted to correct GPT errors.
add map loop1p1 (254:4): 0 2201600 linear 7:1 2048
add map loop1p2 (254:5): 0 4194304 linear 7:1 2203648
add map loop1p3 (254:6): 0 993814528 linear 7:1 6397952

In this case there seems to be no problems mounting loop1p1 and loop1p2, but with `loop1p3, which I understand corresponds to the Ubuntu root system, there is no way. 3. gdisk

# gdisk -l mini.img
GPT fdisk (gdisk) version 1.0.9.1

Partition table scan:
  MBR: protective
  BSD: not present
  APM: not present
  GPT: present

Found valid GPT with protective MBR; using GPT.
Disk mini.img: 1000215296 sectors, 476.9 GiB
Sector size (logical): 512 bytes
Disk identifier (GUID): 74BC899D-E8BA-4C70-B82D-6F4E8F6343A3
Partition table holds up to 128 entries
Main partition table begins at sector 2 and ends at sector 33
First usable sector is 34, last usable sector is 1000215182
Partitions will be aligned on 2048-sector boundaries
Total free space is 4717 sectors (2.3 MiB)

Number  Start (sector)    End (sector)  Size       Code  Name
   1            2048         2203647   1.0 GiB     EF00
   2         2203648         6397951   2.0 GiB     8300
   3         6397952      1000212479   473.9 GiB   8300

What am I doing wrong?

I cannot unmount a partition on which I created and then deleted mappings with kpartx: # mount /dev/sdb1 usb/ # cd usb/ # kpartx -a -p sda -r -s -v sda.img add map loop0sda1 (254:5): 0 16777216 linear 7:0 2048 add map loop0sda2 (254:6): 0 16777216 linear 7:0 16779264 add map loop0sda3 (254:7): 0 440401920 linear 7:0 33556480 add map loop0sda4 (254:8): 0 26159792 linear 7:0 473958400 # kpartx -dv /dev/loop0 del devmap : loop0sda4 del devmap : loop0sda3 del devmap : loop0sda2 del devmap : loop0sda1 # cd .. #umount usb/ target is busy. as far as i can tell, the command kpartx -dv /dev/loop0 properly deleted the mappings, as I can see they have disappeared from /dev/mapper/. But still I cannot unmount the disk, because it reports: target is busy. lsof shows no files open from that disk: # lsof +D Why cannot i unmout the disk after all mappings have been freed up ?