Questions tagged [qcow2]

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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?
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19 views

Noop convert qcow2 image but keeps internal snapshots

I have a qcow2 image. The image size is 200 GB, but the actual use is only 30 GB. I'm using qemu-img convert -O qcow2 source.qcow2 shrunk.qcow2 to removes sparse space and the images shrinks correctly ...
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0answers
17 views

State of OCFS2 as KVM storage for QCOW2 format

Using a shared iSCSI SAN all SSD and good cluster aware filesystems are few and far between with Linux. What is the state of OCFS2 with modern Linux kernels and is it considered reliable enough to ...
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17 views

Live backup for vm guest with qcow2 format

I have created VM guest "my_container" with format qcow2. So when I run command virsh domblklist my_container I am getting this information: [root@mainmachine ~]# virsh domblklist ...
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KVM - Restore metadata of VMs

Is there a way to restore VMs metadata which were located on KVM that was rebuilt? We tried to upgrade one of our KVMs today, and during this process we encountered some issues which led us to rebuild ...
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1answer
168 views

How do I make a compressed disk image (qcow2 and/or squashfs) from a disk directly?

I have a disk attached to my server and I want to make the disk image of it downloadable on the same server. The disk itself is 500GB but I don't want to have a 500GB disk image for download. I'd like ...
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0answers
25 views

Set Ubuntu login credential from Openstack Horizon dashboard

I am trying to create password for Ubuntu Instance I want to use Horizon dashboard to initiate Ubuntu credential. Using focal-server-cloudimg-amd64 Tried using the below in Horizon Customization ...
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2answers
171 views

Terraform Libvirt - How to use local qcow2 file in the hypervisor instead of cloud images?

It seems like the libvirt provider only takes pre-defined cloud images. I create my own base qcow2 image that is local to the hypervisor and wish to use it as source file with terraform libvirtd. Is ...
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2answers
255 views

Migrate ESXi vm to qcow2 with settings preserved?

I have attempted to export a vm in ESXi which produced 3 files: vm_name.ovf (12KB) disk-0-2.vmdk (73KB) disk-1.vmdk (1.2GB) I assumed the larger file (disk-1.vmdk) was the flat file and ...
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1answer
299 views

customize qcow2 ubuntu image fail

I download qcow2 ubuntu 18.04 img from here: https://cloud-images.ubuntu.com/bionic/current/bionic-server-cloudimg-amd64.img I want to add some packages into qcow2 image before use it as a base img ...
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0answers
95 views

How to check the cache mode of a qcow2 image?

Say I converted an image to writethrough cache mode with this command: qemu-img convert -t writethrough -O qcow2 in-image.qcow2 out-image.qcow2 How can I check/verify the cache mode of the image?
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1answer
1k views

Is there a way to convert qcow2 images to ovf format?

I have one qcow2 image. But, I need image in ovf format. I know there is already one answer here Any way to convert qcow2 to ovf?, but I don't have vCenter installed with me. So, i am looking for any ...
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1answer
228 views

qcow2 image: ERROR refcount block 69 is outside image

I have this backup.qcow2 image which was working fine in my kvm/qemu virtual machine before. When I attach it to another virtual machine, Windows recognizes the disk but fails to read partitions. The ...
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1answer
1k views

Convert QCOW2 to VMDK (Citrix Xen)

Hy everyone, the search function does not come up with a propper solution. I want to convert a old KVM disk QCOW2 to an compatible Ctrix Xen disk e.g. VMDK with that qemu-img converting tool qemu-...
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2answers
84 views

Which file has chaged from one VM-overlay to the next?

I've a base image of a windows10 machine. [win10_base image].qcow2 -- [overlay_with_bug].qcow2 I have a bug of a app which I can reproduce. This bug does alter something on the system. I want to ...
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0answers
85 views

Trim qcow2 disk

vps disk size does not updates on server when you delete files within vps. For example one vps had 1TB usage, I deleted 800GB in that vps but vps disk size is still 1TB on server.
3
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1answer
914 views

Ansible fails at “Gathering hosts” presumably because SSH is slow to connect. Setting `UseDNS no` resolves the issue

I am having what appears to be a DNS related issue that I would appreciate some assistance resolving. I'm using Ansible to provision a Kubernetes cluster on my Proxmox server. The project works in ...
2
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1answer
197 views

xfs_db reports high file fragmentation where VM is located, but VM shows almost no fragmentation

I have several libvirt VMs stored on xfs partitions and am using gluster to replicate the storage. The VMs use qcow2 for storage. Some of the partitions where the VMs are located indicate high file ...
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0answers
38 views

QEMU clarifications and setup optimizations

We are using qemu with kvm acceleration. I wanted to understand the -drive flag, currently we are using it as follows: -drive file=<qcow2 snapshot file> if=virtio I have the following ...
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1answer
60 views

KVM file size issue on RHEL 6.9

I tried to allocate 60GB of additional storage to my Win7 KVM by adding a new disk under 'Hardware Settings' using Add Hardware. But the new disk didn't show up in Win7 so i deleted the Disk using ...
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3answers
6k views

How to replace of KVM image to other partition?

i have this structure of space of hdd-s: df -h Filesystem Size Used Avail Use% Mounted on udev 16G 0 16G 0% /dev tmpfs 3.2G 8.9M 3.2G 1% /run /dev/md2 ...
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1answer
492 views

How do Centos cloud images map to iso images

Is it possible to figure out which cloud image maps to which iso release for Centos. I would like a Centos 7.3 minimal image, but when I browse the Centos cloud image site I cannot see any references ...
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2answers
3k views

KVM snapshotting. How to see what's inside the qcow2 file?

I use qcow2 file format and create snapshots using a Virt-manager GUI. I assume I have 100GB disk space and 70% is used by VM at this moment. The qcow2-file size is about 70GB. I create a snapshot. ...
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1answer
5k views

KVM guest qcow2 larger than disk size

I have a Windows 10 VM running on a server that I need to move to another server. The trouble is that the qcow2 file size is too large for the target server. What's odd about this is that the ...
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1answer
252 views

Cannot upload file to qcow2 image file using guestfish on rhel 7.3

I am trying to write a temp file into a qcow2 image file using guestfish as follows: [root@localhost home]# guestfish --rw -i -a vm.qcow2 upload temp /home/ and faced the following problem: ...
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1answer
252 views

Is it safe to use overlay as new VM from QCOW2 image for multiple users?

As title states, is it safe to give overlay of same image to multiple different users? From security standpoint, do they have access to other users data? Can any user corrupt/change base image or ...
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2answers
2k views

qemu-img convert CentOS7 vmdk to qcow2 and vice versa error

I'm trying to convert CentOS7 from VMDK to QCOW2 and vice versa using qemu-img convert command. when uploading the new Templates (OVF with the new converted vmdk and KVM template with the new ...
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2answers
14k views

How to repair a broken-resized qcow2 disk image for libvirt/kvm?

Today I wanted to increase the size of a VM, so I did what I always do (have done it before): qemu-img resize diskimage.qcow2 +22GB Then the file broke and the VM does not start any more. I tried ...
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2answers
8k views

How to create a qcow2 file that is not thin provisioned?

When I do the below then the qcow2 file is less than 200KB. # qemu-img create -f qcow2 /var/lib/libvirt/images/urb-dat0.qcow2 10G # du -hsc /var/lib/libvirt/images/urb-dat0.qcow2 196K /var/lib/...
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1answer
493 views

Is it safe to use fallocate --dig-holes while being modified

Is it safe to use fallocate --dig-holes on a file while it is being modified/written? For example on a QCOW2 image opened by a KVM guest?
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0answers
620 views

Creating OVF headless with generated vmdk

I am looking to create an OVF file during a nightly build process. I currently have this process creating a qcow2 image, which I convert to vmdk using qemu. qemu-img convert -f qcow2 ${image_name} -O ...
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5answers
12k views

QCOW2 virtual size lowering

I'm trying to get the virtual size of a qcow2 container down so that it can fit in a openstack flavor with 10GB disk. root@node-10:~# qemu-img info zztop.qcow image: zztop.qcow file format: qcow2 ...
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2answers
2k views

Accessing linux guest OS filesystem in qcow2 image

I'm attaching VM qcow2 image to get access to files which inside: modprobe nbd max_part=63 qemu-nbd -n -c /dev/nbd0 /var/lib/libvirt/images/vm-image.qcow2 scanning for volume groups vgscan: ...
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3answers
2k views

qemu-img: Could not open '/dev/stdin': Could not refresh total sector count: Operation not permitted

I want to transfer block device contents over the network directly into a qcow2 image. I started with a small simulation: [root@okvmh1 default]# dd if=/dev/zero bs=1M count=100 | qemu-img convert -p -...
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0answers
2k views

How slow can be a QCOW2 vm disk (proxmox/KVM) over NFS (dedicated 1Gbit)?

I'm running 3 proxmox 3.4 nodes using NFS shared storage with a dedicated 1GB network switch. root@lnxvt10:~# pveversion pve-manager/3.4-11/6502936f (running kernel: 2.6.32-43-pve) root@lnxvt10:~# ...
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1answer
4k views

(centOS) cloud-init not pulling ssh

Trying to build CentOS 6 qcow2 image with OpenStack guide[http://docs.openstack.org/image-guide/content/centos-image.html]. I'm using "cloud-init" instead of the "/etc/rc.d/rc.local" script but I ...
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1answer
50k views

How do you create a qcow2 file that is small yet commodious on a Linux server?

I believe that there are qcow2 files that displace a small amount of gigabytes on a server (as verified with a df -h on the physical server) yet allow for lots of space when you log into the virt-...
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1answer
1k views

Edit /etc/resolvconf/resolv.conf.d/base in Centos 7 — qcow2 image

My qcow2 image uses local nameserver, 192.168.122.1 which is not working for reasons unknown. So, I tried to use guestfish and edit the file /etc/resolv.conf to add nameservers, 8.8.8.8. This doesnt ...
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0answers
236 views

Boot a qcow2 image in Ganeti

I am very confused on how Ganeti actually boots machines. My problem is quite simple. I have a qcow2 image in a machine and I want to boot it. How can I do it? I don't really understand the idea of ...
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2answers
99k views

Which is better image format, raw or qcow2, to use as a baseimage for other VMs?

I am using a baseimage and based on that creating many VMs. And now I want to know which is better, qcow2 or raw to use for a baseimage. Moreover, can you please tell me if there is any advantage of ...
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1answer
1k views

How to backup running KVM guest qcow2 disk without LVM?

How to backup running KVM guests, when using qcow2 disks and host system does not use a LVM? Is it even possible without guest shutdown?
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4answers
7k views

KVM virt-clone while the VM is running

Is it possible to clone a running kvm machine without tools like virt-clone? They already have the original vm in production, I cannot shut it down. If I don't care about temporary data corruption (...
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2answers
3k views

How do I make KVM images with LVM partitioning be thinly provisioned with a max growth size?

BACKGROUND: Up to now, I have been provisioning VMs as follows: Create template/gold VM: Create new CentOS 6.6 VM with raw 200GB disk (1 .xml file, 1 .img file) LVM partitioning with: /boot, swap, ...
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1answer
2k views

Qcow2 images growing far beyond what they should

I am using ubuntu 12.04 and have seen this: https://bugs.launchpad.net/ubuntu/+source/qemu-kvm/+bug/1025244 Our qcow2 images are growing far beyond what they should... with some of them growing to as ...
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1answer
23k views

Any way to convert qcow2 to ovf?

In our application we are downloading a qcow2 image and after that we are supposed to import that as OVF. So any way to convert qcow2 --> OVF or qcow2 --> vmdk(using qemu-img convert) --> ...
2
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1answer
497 views

OpenStack EC2 Ubuntu cloud image — SSH host keys were changed after emegency reboot

Recently one of our servers was hanged due to IPMI BMC failure. It is CentOS 6.3 OpenStack compute host serving KVM vitual machines with qcow2 backend. There was running a VM based on EC2 Ubintu ...
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2answers
1k views

qcow2 overlay growing too rapidly

virsh 0.10 I am using qcow2 overlay and a backing file, also qcow2. The overlay is growing way too quick, more than 20 GB in 24 hours, even though I am not writing very much to disk. Is this normal?...
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1answer
2k views

Qcow2 backing image and overlay idea

I have 2 KVM servers running Windows Guests. I want to create a Qcow2 image with Windows 7 on it, install the base software needed, and then make that a backing image, read-only, with one qcow2 ...
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1answer
287 views

Mounting an LVM snapshot and converting file: is it safe?

I have KVM running and need to convert some qcow2 disk images from running guests into vmdk format. Is it safe to take an LVM snapshot of the logical volume that the qcow2 file resides on, mount it, ...
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1answer
635 views

Clone/Backup Strategy for VMs between ESXi and KVM requiring clones to run concurrently with original VMs

I am stuck on this problem and need help. ESXi Free version 5 and qemu-kvm/libvirtd version 0.10. I will put the TL;DR first since it captures the problem fairly well. TL;DR I have 2 VMs on a KVM ...