Pre-allocate qemu-img

allocate-image.sh

#!/bin/sh

#set -e

green="\033[32m"
red="\033[31m"
normal="\033[0m"

log() {
	if [ $? -eq 0 ];
	then
		echo "$green[*]$normal $1"
	else
		echo "$red[*]$normal $1"
		exit 1
	fi
}

execute() {
	$1 > /dev/null 2>&1
}

if [ $# -lt 2 ];
then
	echo "$0 <name> <size in GB>"
	exit 1
fi

name=$1
size=$2
format=qcow2

execute "qemu-img create -f $format -o preallocation=metadata $name.img ${size}G"
log "Creating a ${size}G image file"

bytes=`ls -l $name.img | cut -d ' ' -f5`

execute "fallocate -l $bytes ${name}.img"
log "Pre-allocating $bytes bytes for image"

execute "qemu-img info $name.img"
log "Image information"