kvm-87: qemu-img creates raw file with wrong size

Greetings,

Running qemu-img create -f raw file.raw 1000 creates a 512 byte file rather than the 1000K file the docs imply.

From the help message:
"
'size' is the disk image size in kilobytes. Optional suffixes 'M' (megabyte, 1024 * 1024) and 'G' (gigabyte, 1024 * 1024 * 1024) are supported any 'k' or 'K' is ignored
"

Did the default change or is there bug with the create?

Quoted 6 lines · Randy Smith

Greetings,

Running qemu-img create -f raw file.raw 1000 creates a 512 byte file rather than the 1000K file the docs imply.

Quoted 9 lines

From the help message:
"
'size' is the disk image size in kilobytes. Optional suffixes 'M' (megabyte, 1024 * 1024) and 'G' (gigabyte, 1024 * 1024 * 1024) are supported any 'k' or 'K' is ignored
"

Did the default change or is there bug with the create?

No suffix assumes bytes.  It truncates to the nearest sector which is why you see a 512 byte file.  If you did qemu-img create -f raw file.raw 1024 you would see a file of 1024 bytes.

Not sure if the docs is wrong or this behavior changed.  Patch either way would be appreciated/accepted.

Quoted 17 lines · Anthony Liguori

Quoted 6 lines · Randy Smith

Greetings,

Running qemu-img create -f raw file.raw 1000 creates a 512 byte file rather than the 1000K file the docs imply.

Quoted 9 lines

From the help message:
"
'size' is the disk image size in kilobytes. Optional suffixes 'M' (megabyte, 1024 * 1024) and 'G' (gigabyte, 1024 * 1024 * 1024) are supported any 'k' or 'K' is ignored
"

Did the default change or is there bug with the create?

Quoted 6 lines

No suffix assumes bytes. It truncates to the nearest sector which is why you see a 512 byte file. If you did qemu-img create -f raw file.raw 1024 you would see a file of 1024 bytes.

Not sure if the docs is wrong or this behavior changed. Patch either way would be appreciated/accepted.

It looks like the behavior changed. The ubuntu-vm-builder depended on 'size' defaulting to kilobytes and the help message printed when qemu-img is run claims that it should default to kilobytes.

Here's a patch that updates the help message. It doesn't matter to me if the behavior changed here but as long as the docs match what's really happening.

qemu-img.c renamed from qemu-img.c.orig +0 -0

@@ -78,7 +78,7 @@
           "    content as the input's base image, however the path,

image format, etc may\n"
" differ\n"
" 'fmt' is the disk image format. It is guessed
automatically in most cases\n"
- " 'size' is the disk image size in kilobytes. Optional
suffixes\n"
+ " 'size' is the disk image size in bytes. Optional
suffixes\n"

           "    'M' (megabyte, 1024 * 1024) and 'G' (gigabyte, 1024 *

1024 * 1024) are\n"
" supported any 'k' or 'K' is ignored\n"
" 'output_filename' is the destination disk image
filename\n"