KVM 虚机镜像扩容和压缩的操作

# 创建一个设备空间大小为10G的镜像
qemu-img create -f qcow2 centos7-guest.qcow2 10G
# 基于backing_file创建大小为20G的镜像, 使用-b参数, -F用于指定backing_file的格式
qemu-img create -F qcow2 -b /path/to/backing-kvm.img -f qcow2 /path/to/target.qcow2 20G
# 基于backing_file创建大小为20G的镜像, 使用-o参数, 都在-o参数内指定
qemu-img create -f qcow2 -o backing_file=/path/to/rhel6u3.img,backing_fmt=qcow2,size=20G /path/to/target.qcow2

qemu-img info rhel6u3.img

qemu-img convert -f raw -O qcow2 centos.img centos.qcow2
qemu-img convert -f qcow2 -O raw centos.qcow2 centos.raw

fstrim -av

dd if=/dev/zero of=/mytempfile
# 删除产生的文件
rm -f /mytempfile

fsutil behavior query DisableDeleteNotify

fsutil behavior set DisableDeleteNotify 0

sdelete -z

sdelete -z e:

qemu-img convert -O qcow2 vm_pbc.qcow2 vm_pbc_shrink.qcow2

qemu-img convert -O qcow2 -c vm_pbc.qcow2 vm_pbc_shrink.qcow2

virt-filesystems --long --parts --blkdevs -h -a c7guest1.qcow2c 
Name       Type       MBR  Size  Parent
/dev/sda1  partition  83   8.0G  /dev/sda
/dev/sda   device     -    8.0G  -

# 创建一个50G容量的qcow2空白镜像
qemu-img create -f qcow2 /data/images/win2012-50gb.qcow2 50G
# 将镜像扩充到新镜像中去, 通过--expand指定需要扩张的分区
virt-resize --expand /dev/sda2 /data/images/win2012.qcow2 /data/images/win2012-50gb.qcow2

# 查看分区
df -h
# 查看分区对应的磁盘大小, 能看出来/dev/vda1已经增长, 但是未体现到df -h的输出中
fdisk -l
# 如果/dev/vda1格式是xfs
xfs_growfs /dev/vda1
# 如果/dev/vda1格式是ext2,3,4
resize2fs /dev/vda1

# 先检查镜像的分区结构, 以便后面对指定的分区进行扩容
virt-filesystems --long --parts --blkdevs -h -a vm_n01.qcow2 
# 更名
mv vm_n01.qcow2 vm_n01.qcow2.bak
# 用原名创建一个40G的空白镜像
qemu-img create -f qcow2 vm_n01.qcow2 40G
# 将旧镜像导入到空白镜像
virt-resize --expand /dev/sda1 vm_n01.qcow2.bak vm_n01.qcow2
# 检查导入后的新镜像
virt-filesystems --long --parts --blkdevs -h -a vm_n01.qcow2
# 删除旧镜像
rm vm_n01.qcow2.bak

# 查看分区
df -h
# 查看分区对应的磁盘大小, 能看出来/dev/vda1已经增长, 但是未体现到df -h的输出中
fdisk -l
# 如果/dev/vda1格式是xfs
xfs_growfs /dev/vda1
# 如果/dev/vda1格式是ext2,3,4
resize2fs /dev/vda1

virt-resize: error: libguestfs error: resize2fs: e2fsck 1.42.9 
(28-Dec-2013)
/dev/sda1 has unsupported feature(s): metadata_csum
e2fsck: Get a newer version of e2fsck!

# 需要预先安装 wget gcc-c++
sudo wget https://mirrors.edge.kernel.org/pub/linux/kernel/people/tytso/e2fsprogs/v1.46.4/e2fsprogs-1.46.4.tar.gz
sudo tar xvf e2fsprogs-1.46.4.tar.gz
sudo cd e2fsprogs-1.46.4
sudo ./configure
sudo make
sudo make install
sudo yum -y install libguestfs-xfs

# resize原始镜像
qemu-img resize focal-server-cloudimg-amd64-50g.qcow2 50G
# 转换为raw格式镜像
qemu-img convert -f qcow2 -O raw focal-server-cloudimg-amd64-50g.qcow2 focal-server-cloudimg-amd64.raw
# 重命名以防混淆
mv focal-server-cloudimg-amd64.raw focal-server-cloudimg-amd64-50g.raw
# 运行parted
parted focal-server-cloudimg-amd64-50g.raw 
######################## 开始
GNU Parted 3.1
Using /data/backup/vm_images/focal-server-cloudimg-amd64-50g.raw
Welcome to GNU Parted! Type 'help' to view a list of commands.
(parted) p                                                                
Error: The backup GPT table is not at the end of the disk, as it should be.
This might mean that another operating system believes the disk is smaller.
Fix, by moving the backup to the end (and removing the old backup)?
Fix/Ignore/Cancel? Fix                                                    
Warning: Not all of the space available to
/data/backup/vm_images/focal-server-cloudimg-amd64-50g.raw appears to be used,
you can fix the GPT to use all of the space (an extra 100245504 blocks) or
continue with the current setting? 
Fix/Ignore? Fix                                                           
Model:  (file)
Disk /data/backup/vm_images/focal-server-cloudimg-amd64-50g.raw: 53.7GB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Disk Flags: 
Number  Start   End     Size    File system  Name  Flags
14      1049kB  5243kB  4194kB                     bios_grub
15      5243kB  116MB   111MB   fat32              boot
 1      116MB   2361MB  2245MB  ext4
(parted) resizepart                                                     
Partition number? 1                                                       
End?  [2361MB]? 53.7G                                                     
 1      116MB   53.7GB  53.6GB  ext4
(parted) q                                                                
########################### 结束
# 查看raw格式的分区大小是否正确
virt-filesystems --long --parts --blkdevs -h -a focal-server-cloudimg-amd64-50g.raw 
Name        Type       MBR  Size  Parent
/dev/sda1   partition  -    50G   /dev/sda
/dev/sda14  partition  -    4.0M  /dev/sda
/dev/sda15  partition  -    106M  /dev/sda
/dev/sda    device     -    50G   -
# 转回qcow2格式
qemu-img convert -f raw -O qcow2 focal-server-cloudimg-amd64-50g.raw focal-server-cloudimg-amd64-50g-resized.qcow2
# 再次检查
virt-filesystems --long --parts --blkdevs -h -a focal-server-cloudimg-amd64-50g-resized.qcow2