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Questions tagged [qcow2]

76 questions
37
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6 answers

Incredibly low KVM disk performance (qcow2 disk files + virtio)

I'm having some serious disk performance problems while setting up a KVM guest. Using a simple dd test, the partition on the host that the qcow2 images reside on (a mirrored RAID array) writes at over 120MB/s, while my guest gets writes ranging…
El Yobo
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34
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6 answers

free up not used space on a qcow2-image-file on kvm/qemu

we are using kvm/qemu with qcow2-images for our virtual machines. qcow2 has this nice feature where the image file only allocates the actually needed space by the virtual-machine. but how do i shrink back the image file, if the virtual machine's…
bmaeser
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32
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5 answers

Is there any way to shrink qcow2 image without converting it raw?

Is there any way to shrink qcow2 image without converting it raw? I cannot convert it to raw because I don't have disk space enough for raw image.
YOU
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31
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2 answers

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 using this baseimage thing, instead of cloning the…
A-B
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13
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1 answer

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-manager VM and issue a df -h. How do you create such…
Catbird55
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9
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2 answers

mount qcow2 snapshots

I'm running some Xen-servers and started migrating to KVM. Currently my guests are either running on raw-images or LVMs. I found libvirt providing some very nice snapshot features (virsh snapshot-create, ...) so I decided to use qcow2 instead of…
phhe
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8
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2 answers

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 booting the VM from CD to adjust partitioning but…
Ned64
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6
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2 answers

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/libvirt/images/urb-dat0.qcow2 If I attach it to a…
Jasmine Lognnes
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6
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4 answers

Do I need to zero-fill a qcow2 image before compacting it?

I want to recreate a dynamically allocated qcow2 image in order to shrink it. Is it sufficient that all unnecessary files have been deleted, or do I also need to fill the space formerly occupied by those files with zeros? In other words, is qemu-img…
Josh
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5
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2 answers

Backup of KVM guests when using qcow2 disk files

I got a Ubuntu (hardy) system used for virtualization using KVM. Each guest got it's own qcow2 file used as disk. Guests are running Ubuntu (hardy). What would a good backup strategy be for such a setup? I would prefer not to shutdown the guests…
rkthkr
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5
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5 answers

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 virtual size: 80G (85899345920 bytes) disk size:…
Duncan Fairley
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5
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1 answer

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) --> ovf .
Reuben
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4
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4 answers

DRBD & KVM replication is possible?

i have two KVM servers with some virtual machines. Server (A) KVM with qcow2 images Server (B) KVM mount NFS for partiton (with qcow2 images present on server A). My question is simple, what is the best solution for creating virtual disk copies on…
Giovanni Bennelli
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4
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2 answers

conversion of a VMDK image with qemu-img failed with "error while reading sector 131072: Invalid argument"

I tried to convert a VMDK image found in a OVA file to the QCOW2 format with the qemu-img command but it failed with the error message qemu-img: error while reading sector 131072: Invalid argument user@ubuntu:/tmp$ wget…
Erik Sjölund
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4
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1 answer

How to convert a raw disk image to a copy-on-write image based on another image for use with kvm and virt-manager?

I have a virtual Windows machine running on kvm. Presently it has a 90GB raw disk image. I would like to clone this VM without having to keep two copies of the 90GB raw disk image around. It seems like a good approach for doing this is to make two…
Jean-Paul Calderone
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