[libvirt-users] Slow network performance issues

[Dominique Ramaekers]

Is the rsync a first copy or are you overwriting a previous copy. How fast is the transfer rate with scp?


-----Oorspronkelijk bericht-----
Van: Alex Regan [mailto:mysqlstudent at gmail.com] 
Verzonden: maandag 29 juni 2015 4:46
Aan: libvirt-users at redhat.com
Onderwerp: [libvirt-users] Slow network performance issues

Hi,
I have a fedora21 system that's been running fine under normal network activity, but trying to perform a full backup of the 300GB filesystem is taking forever because the network speed appears to be very slow.

Using rsync, the transfer speeds reach a max of like 180kB/s. Using rsync to copy files on the local filesystem is greater than 55MB/s, so I don't think it's a disk issue.

What kind of network speed can I expect copying data across the network from the guest to another host on the same gigabit network?

I'm using the virtio driver:

# lsmod|grep virtio
virtio_console         28672  0
virtio_balloon         16384  0
virtio_net             32768  0
virtio_blk             20480  4
virtio_pci             24576  0
virtio_ring            20480  5 
virtio_blk,virtio_net,virtio_pci,virtio_balloon,virtio_console
virtio                 16384  5 
virtio_blk,virtio_net,virtio_pci,virtio_balloon,virtio_console

ethtool on the vnet0 interface shows the speed at only 10Mb/s. Is that normal? Or even changable?

I've included the qemu command-line below.

# ps ax|grep propguest
  1582 ?        Sl   25433:37 /usr/bin/qemu-system-x86_64 -machine 
accel=kvm -name propguest -S -machine pc-1.2,accel=kvm,usb=off -m 16384 -realtime mlock=off -smp 4,sockets=4,cores=1,threads=1 -uuid b67e10fe-7ef0-a1ca-cecf-3f3506d54e1a -no-user-config -nodefaults -chardev socket,id=charmonitor,path=/var/lib/libvirt/qemu/propguest.monitor,server,nowait
-mon chardev=charmonitor,id=monitor,mode=control -rtc base=utc -no-shutdown -device piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2
-device virtio-serial-pci,id=virtio-serial0,bus=pci.0,addr=0x5 -drive file=/var/lib/libvirt/iso-images/Fedora-18-x86_64-DVD.iso,if=none,id=drive-ide0-1-0,readonly=on,format=raw
-device ide-cd,bus=ide.1,unit=0,drive=drive-ide0-1-0,id=ide0-1-0 -drive
file=/var/lib/libvirt/images/propguest.img,if=none,id=drive-virtio-disk0,format=qcow2
-device
virtio-blk-pci,scsi=off,bus=pci.0,addr=0x6,drive=drive-virtio-disk0,id=virtio-disk0,bootindex=1
-drive
file=/var/lib/libvirt/images/propguest-2.img,if=none,id=drive-virtio-disk2,format=raw
-device
virtio-blk-pci,scsi=off,bus=pci.0,addr=0x9,drive=drive-virtio-disk2,id=virtio-disk2
-netdev tap,fd=23,id=hostnet0,vhost=on,vhostfd=24 -device
virtio-net-pci,netdev=hostnet0,id=net0,mac=52:54:11:66:5a:51,bus=pci.0,addr=0x3
-chardev pty,id=charserial0 -device
isa-serial,chardev=charserial0,id=serial0 -chardev spicevmc,id=charchannel0,name=vdagent -device
virtserialport,bus=virtio-serial0.0,nr=1,chardev=charchannel0,id=channel0,name=com.redhat.spice.0
-device usb-tablet,id=input0 -spice
port=5900,addr=127.0.0.1,disable-ticketing,seamless-migration=on -device
qxl-vga,id=video0,ram_size=67108864,vram_size=67108864,bus=pci.0,addr=0x2 -device
intel-hda,id=sound0,bus=pci.0,addr=0x4 -device
hda-duplex,id=sound0-codec0,bus=sound0.0,cad=0 -device
virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x8

Any ideas greatly appreciated.
Thanks,
Alex

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