Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.debian.user > #178065

Re: virtual disks perfermonca <=2MB/s

Show all headers | View raw

On Wed, Feb 22, 2017 at 10:17:01AM +0200, Mimiko wrote:
>Hello.
>
>I already wrote to qemu mail list and didn't find an answer.
>
>I've setup qemu / kvm on Debian Wheezy to host some Debian Jessie guests.
>I create disk like this:
>
>virsh vol-create-as --pool default --name root.vhd --capacity 50G --format vpc
>
>Then create a virtual with this:
>virt-install --connect qemu:///system \
>--ram 2048 \
>--vcpus=4 \
>--cpuset=auto \
>--pxe \
>--os-type linux \
>--boot network,hd,menu=on \
>--disk vol=default/root.vhd,device=disk,bus=virtio,cache=writethrough \
>--network=bridge:br0,model=virtio \
>--noautoconsole \
>--hvm \
>--autostart \
>--check-cpu
>
>After setting up the system I've got poor disk performance.
>Using
>
>time dd if=/dev/zero of=/tmp/test oflag=direct bs=64k count=16000
>
>I get 1048576000 bytes (1.0 GB) copied, 397.473 s, 2.6 MB/s
>
>I've changed cache to writeback and got 20MB/s with this test. But copying a file to this virtual using samba gives me no more of 2 MB/s.
>
>I've tested network connectivity with iperf and got around 750Mbit/s, which I think is satisfactory.
>
>I will not want to use raw devices, as it is not self expanded and will use whole space regardless of how much real data occupy.
>
>libvirtd (libvirt) 0.9.12.3
>
>Is there a way to increase disk speed to at least 50MB/s ?

StackExchange 
(http://serverfault.com/questions/407842/incredibly-slow-kvm-disk-performance-qcow2-disk-files-virtio) 
suggests that QCOW2 may be a factor, and to use:

 $ qemu-img create -f qcow2 -o preallocation=metadata,compat=1.1,lazy_refcounts=on imageXYZ

but there's a bunch of other cargo-cult options to try, too! :D


-- 
For more information, please reread.

Back to linux.debian.user | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

virtual disks perfermonca <=2MB/s Mimiko <vbvbrj@gmail.com> - 2017-02-22 09:20 +0100
  Re: virtual disks perfermonca <=2MB/s Joel Wirāmu Pauling <joel@aenertia.net> - 2017-02-22 09:50 +0100
    Re: virtual disks perfermonca <=2MB/s Mimiko <vbvbrj@gmail.com> - 2017-02-22 14:00 +0100
  Re: virtual disks perfermonca <=2MB/s Darac Marjal <mailinglist@darac.org.uk> - 2017-02-22 15:10 +0100
    Re: virtual disks perfermonca <=2MB/s Mimiko <vbvbrj@gmail.com> - 2017-02-22 15:50 +0100

csiph-web