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Questions tagged [qcow2]

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Use .qcow2 VM file format for VirtualBox

VirtualBox, supports several other file formats, but no .qcow2 format for the time being. The Virtmanager, in turn supports the current open source .qcow2 format, but not the outdated .qcow format. ...
Alfred.37's user avatar
  • 120
-1 votes
2 answers
76 views

Limiting the file size of .qcow2 files [closed]

Qcow 2 files are an open source file format for virtual machines. In my opinion, unlike .vmdk files, they do not offer the option of specifying a maximum file size. This means that they can constantly ...
Alfred.37's user avatar
  • 120
0 votes
0 answers
44 views

Write QCOW2 image to iSCSI LUN?

I've been trying to write a QCOW2 image to an iSCSI LUN target but have been unsuccessful. Based on this link, this should be possible (and should be possible without having to mount the iSCSI LUN as ...
quantum's user avatar
  • 101
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0 answers
133 views

How do I merge my sequential raw backup images into one single qcow2 image with snapshots?

I have collected a number of raw disk image clones from an embedded system over a long time, each about 2 GB: root141221.dd 2048901120 root150221.dd 2048901120 root160408.dd 2048901120 root170821.dd ...
pipe's user avatar
  • 925
1 vote
1 answer
506 views

Why is it recommended to add nodatacow to a VM image on BTRFS, but using a QCOW2 disk is ok?

As far as I know, it is recommended to disable copy on write for VM images to avoid performance degradation on BTRFS. However, no one recommends against using qcow2 disk image format, despite being a ...
td211's user avatar
  • 394
1 vote
0 answers
279 views

Delete snapshots only in libvirt, but retain them in qcow2

I executed the following commands -- 12:18:40 sudo virsh snapshot-delete Windows-10-128GB 2022-04-12-Pre-Activation Domain snapshot 2022-04-12-Pre-Activation deleted ...
Daniel F's user avatar
  • 877
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0 answers
244 views

cannot import qcow2 image in virt-manager to other vm

I have installed debian to a qcow2 image to prepare it for usage in a paravirtualized vm and have tried to import it on another vm. Virt-manager doesn't give any errors, however from the OVMF bios it ...
MaxBrandtner's user avatar
0 votes
0 answers
170 views

Archive qemu image

How do I archive qemu images with the same efficiency as gcloud This command stub show efficiency. Around 80% on pre installed images of OSes notorious for their install size. 40g actual physical ...
John Peterson's user avatar
2 votes
1 answer
1k views

What happens if I run a VM while copying the qcow2 file / can I backup by copying the VM file while running?

I'm trying to understand how the write happens with a VM. It looks like running one is not blocked while copying it for a backup. Will the copy contain any modified files like the boot log? Or will it ...
alchemy's user avatar
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0 answers
1k views

qemu-img command doesn't create the qcow2 file

I am using a macOS 12.2.1 with m1 chip. I successfully installed qemu using brew. I am trying to convert my ubuntu iso file to qcow2. When I run, qemu-img create -f qcow2 ubuntu-20.04.3-live-server-...
Jason's user avatar
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0 votes
1 answer
206 views

When is a disk sync necessary on qcow2?

I'm running Apache on a VM with a qcow2 disk. Apache runs a (compiled C++) program which does the following: It calls system to run another (C++) program which creates a file It then attempts to ...
EML's user avatar
  • 223
3 votes
1 answer
4k views

Can qemu-img uncompress qcow2 file?

We can use the -c option for qemu-img to compress the qcow2 file, e.g., here, but at the cost of uncompressing it while using. Suppose I am given a compressed qcow2 file, does qemu-img have any option ...
zzzhhh's user avatar
  • 155
0 votes
1 answer
1k views

Get a raw disk image from qcow2 [duplicate]

I want to install Ubuntu (or any distro) as UEFI with QEMU/libvirt and make some changes there at runtime and shut down the machine. This will create a qcow2 disk. If this was not a virtual machine ...
TheMeaningfulEngineer's user avatar
1 vote
1 answer
2k views

How to merge common parts of qemu qcow2 disks

I have a qemu image B.qcow2 that is a snapshot of A.qcow2. I created a copy of B.qcow2 by using cp B.qcow2 C.qcow2 and then worked on both B.qcow2 and C.qcow2 independently. Thus, B.qcow2 and C.qcow2 ...
sebastien dontneedtoknowthat's user avatar
4 votes
2 answers
3k views

How to enable zstd for your qcow2 files

In QEMU 5.1 zstd compression of your qcow2 files was introduced. But it's not described in the manual for qemu-img. How do you enable it?
MrCalvin's user avatar
  • 689
1 vote
1 answer
619 views

After cloning a VM with virt-clone, how do I rename the newly created qcow2 file?

I wanted to build another server based on an existing config, so I performed the following: [user@box ~]# virt-clone --original serverA-rhel8 --name serverB-rhel8 --auto-clone Allocating 'serverA-...
a coder's user avatar
  • 3,253
0 votes
1 answer
668 views

How can I see the version of OS that runs on a VM

Is there any way that I can find out from hypervisor the version of OS that I am runing on a vm. The problem is that I have an upgrade procedure that shuts down a vm, replaces the qcow2 image and then ...
Aris Koutsoukis's user avatar
1 vote
1 answer
3k views

How to increase the root partition size of a virtual machine used by GNOME Boxes (QEMU)?

I use GNOME Boxes on Fedora 32 to virtualize a Fedora Silverblue installation. I did not setup a sophisticated/smart partitioning for my virtual Fedora and have run out of disk space on my virtual ...
justjulian's user avatar
1 vote
1 answer
5k views

How to create partitions on qcow2 image without reserving disk size

I want to install archlinux in UEFI mode so, I created image from virt-manager with size of 20GB. Then after booting into VM, I created 2 partition with fdisk named /dev/vda1 and /dev/vda2 with 512MB ...
user avatar
1 vote
0 answers
625 views

`qemu-nbd` list phantom partitions

When I mount a qcow2, like qemu-nbd --connect=/dev/nbd0 /path/image.qcow2, fdisk /dev/nbd0 -l lists me partition non visible on /dev/. And when I mount /dev/nbd0 /path It only mount what should be the ...
aaa's user avatar
  • 157
0 votes
2 answers
967 views

store a KVM .qcow2 image in NTFS external hard disk

I have a .qcow2 image that became really bigger (36 GB) and I want to move it to an external HD to avoid using all my PC (Debian machine) memory for that. Is it possible to store it (and access it ...
cccnrc's user avatar
  • 255
1 vote
0 answers
652 views

virsh attach-disk only work with name vd* instead of sd*

I have an qcow2 image and want to attach another disk to it. # create new qcow2 disk qemu-img create -f qcow2 vm-disk2 500G Then I attach it as sdb: virsh attach-disk myvm /var/lib/libvirt/images/...
raring-coffee20's user avatar
-1 votes
1 answer
626 views

Open qcow2 image on debian remote server remotely

I recovered a vmware image from an inaccessible server after converting it to qcow2, now it is on a remote debian server (kimsufi) and as it is 64GB I can't download it to my small pc. I read that I ...
Entretoize's user avatar
8 votes
1 answer
4k views

KVM/QEMU/libvirt image path suggestion file system and mount options

As simple KVM server I've got to store raw and qcow2 images on special path like: /kvm-storage I want to know what's the best practices for file system and mount options to set this path for achieve ...
Mohammad Hossein Fattahizadeh's user avatar
2 votes
1 answer
1k views

Set L2 cache for QEMU qcow2 disk in virsh XML

In the QEMU commandline you can set a L2 cache for a disk using l2-cache-size=10M This option is not supported in Virsh XML but it should be able to use the XML element <qemu:commandline> but I ...
MrCalvin's user avatar
  • 689
0 votes
1 answer
510 views

Input/Output on qcow2 mysteriously fixed after reboot

I had error Input/Output error when I was trying to do something on my KVM virtual using qcow2 disk. I read about that its possible corrupted virtual disk, but I just ran virsh destroy and virsh start ...
Delirium's user avatar
  • 378
1 vote
1 answer
14k views

How to clone a single partition from a HD to a qcow2 disk image for use in qemu-kvm?

Edit (1&2): I cloned my working OS (powered off, HD mounted on USB drive, > dd if=/dev/sdc1 of=/data/system.img The original SSD is as follows: > sfdisk -d /dev/sdc # partition table of /...
asoundmove's user avatar
  • 2,505
4 votes
1 answer
2k views

qemu-img convert burning CPU for nothing

I'm trying to reduce the usage of a qcow2 image. I did the following: qemu-img convert -p -f qcow2 -O qcow2 my_img.qcow2.backup my_img.qcow2 I outputs 200192 bytes and progress is stuck at 0.00%. ...
CrazyCasta's user avatar