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Questions tagged [virtio]

51 questions
8
votes
4 answers

How to efficiently share host's folder with KVM guests?

I am configuring the service which stores plenty of files uploaded by nginx in /srv/storage dir on host system. These files are processed by worker KVM guests which may create new files or assign extended attributes to existing ones. Files are never…
gertas
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7
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3 answers

Install windows 2012 R2 over KVM-virtualizaton

I'm trying to install Windows Server 2012 R2 over linux KVM-virtualization. The installation process stops and requires drivers to continue. I'm trying with virtio drivers from fedora but doesn't work. Installation process doesn't show a storage…
Jaime Uriel Torres Serrano
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7
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2 answers

Am I using virtio for my KVM guest?

In one of my KVM guest, when I typed the following command, I get the following /sbin/lsmod | grep vi virtio_balloon 3692 0 So does it mean I am using virtio? Update: When I type cat "/boot/config-`uname -r`" | grep -i vir I can…
Howard
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6
votes
2 answers

qemu-kvm reclamation of memory from low-use guests

Is there a way to transparently reclaim, or prevent usage of, memory from a qemu-kvm guest? Scenario A: A guest uses 8GB of RAM during peak hours, it returns back to 4GB of usage at night, but the guest is still claiming 8GB of RAM from the…
Devon
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5
votes
3 answers

Get link speed of an virtio-net network adapter

I have an linux vm running on kvm with virtio-net, and I want to check the link speed. How can I do that? What I tried so far: # ethtool eth0 Settings for eth0: Link detected: yes It seems that ethtool does not support virtio-net(yet?) I have the…
ddio
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5
votes
1 answer

Poor network performance with KVM (virtio drivers) - Update: with vhost_net

I've set up several KVM based networks before, and never encountered this issue, can't for the life of me think what I'd have set up differently previously. Setup Basically, Ive got and entirely Dell Stack: 2x Dell N2024's (stacked gigabit…
kwiksand
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5
votes
1 answer

Why is there a socket interface on the host and a character device interface on the guest for virtio-serial?

I am trying to establish a communication channel between the host and one of its guest virtual machine using kvm as a hypervisor. For this, I am using virtio-serial. To create the virtual machine, I issued the following command: qemu-system-x86_64…
jobin
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3
votes
1 answer

Migrate CentOS VM using LVM on IDE to run with VirtIO

I'm trying to migrate existing IDE-using, LVM-based CentOS 5.2 VMs to use virtio. The symptom is a kernel panic upon boot when the system can't find any volume groups. Does anyone know how to make this work? I created a vm install that didn't use…
Jerry Seutter
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3
votes
2 answers

slow performance on ssd when using kvm to launch vm's

On my host hardware I have 1G's speed on my vm I create using kvm it drops to around 20MB's My host is running ubuntu 22.04 LTS How can I optimise this? I am using file based VM's. I created disk type raw and qcow2 only difference I saw was the…
shorif2000
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3
votes
1 answer

How to get Linux kernel to rescan virtio disks?

I have a virtio disk mounted to a KVM guest, backed by an LVM logical volume. I increased the size of the logical volume with lvresize on the KVM host machine. Then I had to issue virsh pool-refresh to make the KVM host aware of the volume size…
MegaBrutal
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3
votes
1 answer

Updated VirtIO SCSI driver on my Windows 2012 R2, and now only boots into recovery. How to recover?

I have a Hetzner W2012 R2 Cloud VM, and I updated the VirtIO vioscsi driver on it. Now it only boots into recovery mode and I cannot access the C-drive even from command prompt. Is there any way to save this VM or is it a goner? I have no (recent)…
Casper
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2
votes
1 answer

(QEMU) Setup Windows 10 VM on a thinly-provisioned LVM device with discards (a.k.a. trim)

I'm trying to set up a Windows 10 VM using QEMU and I want to use a thinly-provisioned LVM volume and be able to "retrim" the drive in Windows. I created the device with: -drive index=0,media=disk,if=virtio,format=raw,file=/dev/vg0/myvol, But when…
Daniel Santos
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2
votes
0 answers

Imbalanced IRQs on virtio devices

I noticed in the top on my linux server that one cpu had far more number of software interrupts than all other 7 cores. Digging further, I noticed that this core is pinned to a particular irq which happens to be a virtio device. Infact each core has…
hobgoblin
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2
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0 answers

Is it possible to set an IO scheduler in KVM Guest with VirtIO?

Is it possible to set an IO scheduler in a KVM Guest with VirtIO? With the following command i don't get any options to choose cat /sys/block/vda/queue/schedule none Kerneloption are set: root@jessie:~# egrep 'CONFIG_IOSCHED_.*=y'…
demonking
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2
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0 answers

kvm virtio disk performance scales badly with iozone workload

I'm conducting a number of tests in order understand why some of our workloads generate a really poor "user experience" with db related activities. We have a dl160g9 server with a B140i controller (4 LFF disks 7.2k rpm). host is centos 7, the…
matteo nunziati
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