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2012年6月16日 星期六

KVM Guest with virtio network driver loses network connectivity


最近開始使用 Ubuntu 12.04, Kernel 是 3.2.0, 但發現如果用這版來裝的 VM, 會三不五時遇到網路斷掉的狀況, 系統沒有 Crash, 也只要重啟網路就可以繼續使用, 但老是這樣, 總是讓人感到不方便, 而且後來發現只要流量一大就會發生這個問題, 那影響就很大了. 找了一下網路, 發現這個問題也很多人 遇到, 似乎是 KVM 的 virtio 有 bug.

http://www.mail-archive.com/kvm@vger.kernel.org/msg68530.html

一路測到 3.2.0-26 , 這個問題也都還存在


virsh # version
Compiled against library: libvir 0.9.8
Using library: libvir 0.9.8
Using API: QEMU 0.9.8
Running hypervisor: QEMU 1.0.0

目前有找到兩個暫解

1. turn off event_idx parameter in qemu driver for virtio
  
       a. use libvirt xml
         
             
         

       b. use kvm command
          -device virtio-net-pci,event_idx=off
 
2. turn on vhost

       a. use libvirt
          modprobe vhost_net
          service libvirtd restart
          restart your vm

       b. use kvm command
          -netdev tap,vhost=on

兩個方案都是可行的, 不過第二個方案看起來是比較好的選擇, 因為根據文件還可以加強 Performance. 我用 iperf 測試的結果, 如果是從 vm 從資料到 host 端, 可以達到 13Gbits/sec, 如果不用 virtio, 預設的網卡設定, 大概都只有 150 Mbits/sec, 實在是很慢

另外補上 KVM 的 tuning 網頁

如果是用 virt-install, 可以加上以下幾個參數, 做的事情其實是和上面那篇一樣
-v
--cpu host
--disk bus=virtio,cache=writeback 
--accelerate
--network model=virtio

產生的指令會類似下面
kvm -S -M pc-1.0 -cpu core2duo,+lahf_lm,+rdtscp,+pdpe1gb,+aes,+popcnt,+sse4.2,+sse4.1,+dca,+xtpr,+cx16,+tm2,+est,+vmx,+ds_cpl,+pbe,+tm,+ht,+ss,+acpi,+ds -enable-kvm -m 8192 -smp 1,sockets=1,cores=1,threads=1 -name iscsi-server4 -uuid 035b0292-5866-ddac-e088-4cfd04f8af93 -nodefconfig -nodefaults -chardev socket,id=charmonitor,path=/var/lib/libvirt/qemu/iscsi-server4.monitor,server,nowait -mon chardev=charmonitor,id=monitor,mode=control -rtc base=utc -no-shutdown -drive file=iscsi-server4.qcow2,if=none,id=drive-virtio-disk0,format=qcow2,cache=writeback -device virtio-blk-pci,bus=pci.0,addr=0x4,drive=drive-virtio-disk0,id=virtio-disk0,bootindex=1 -netdev tap,fd=23,id=hostnet0,vhost=on,vhostfd=24 -device virtio-net-pci,netdev=hostnet0,id=net0,mac=52:54:00:1c:9d:f0,bus=pci.0,addr=0x3 -chardev pty,id=charserial0 -device isa-serial,chardev=charserial0,id=serial0 -usb -vnc 0.0.0.0:5 -vga cirrus -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x5





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2012年3月13日 星期二

KVM Installation

https://help.ubuntu.com/11.10/serverguide/C/virtualization.html
http://bojack.pixnet.net/blog/post/29040863-%E3%80%90linux%E3%80%91%E5%9C%A8-ubuntu-11.04-%E4%B8%8A%E5%AE%89%E8%A3%9D-kvm

wistor@wistor-003:~$ kvm-ok
INFO: /dev/kvm exists
KVM acceleration can be used

wistor@wistor-003:~$ lsmod | grep kvm
kvm_intel             137721  3
kvm                   407077  1 kvm_intel

wistor@wistor-003:~$ sudo modprobe -l | grep kvm
kernel/arch/x86/kvm/kvm.ko
kernel/arch/x86/kvm/kvm-intel.ko
kernel/arch/x86/kvm/kvm-amd.ko

wistor@wistor-003:~$ sudo apt-get install kvm libvirt-bin

wistor@wistor-003:~$ cat /etc/network/interfaces
auto lo
iface lo inet loopback

auto br0
iface br0 inet static
        bridge_ports eth0
        bridge_fd 9
        bridge_hello 2
        bridge_maxage 12
        bridge_stp off
        address 172.16.123.83
        network 172.16.0.0
        netmask 255.255.0.0
        gateway 172.16.1.254

auto br0:1
iface br0:1 inet static
    address 192.168.123.83
    netmask 255.255.255.0

wistor@wistor-003:~$ ifconfig
br0       Link encap:Ethernet  HWaddr 00:26:2d:0a:36:7e
          inet addr:172.16.123.83  Bcast:0.0.0.0  Mask:255.255.0.0
          inet6 addr: fe80::226:2dff:fe0a:367e/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:186911 errors:0 dropped:5837 overruns:0 frame:0
          TX packets:79278 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:136435680 (136.4 MB)  TX bytes:8542559 (8.5 MB)

br0:1     Link encap:Ethernet  HWaddr 00:26:2d:0a:36:7e
          inet addr:192.168.123.83  Bcast:0.0.0.0  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1

eth0      Link encap:Ethernet  HWaddr 00:26:2d:0a:36:7e
          UP BROADCAST RUNNING PROMISC MULTICAST  MTU:1500  Metric:1
          RX packets:278356 errors:0 dropped:10 overruns:0 frame:0
          TX packets:91634 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:176265990 (176.2 MB)  TX bytes:9623004 (9.6 MB)
          Memory:fbea0000-fbec0000

lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:98 errors:0 dropped:0 overruns:0 frame:0
          TX packets:98 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:9439 (9.4 KB)  TX bytes:9439 (9.4 KB)

virbr0    Link encap:Ethernet  HWaddr 52:6b:4e:82:ba:f8
          inet addr:192.168.122.1  Bcast:192.168.122.255  Mask:255.255.255.0
          UP BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)



wistor@wistor-003:~$ groups
wistor adm dialout cdrom plugdev lpadmin sambashare admin libvirtd

wistor@wistor-003:~$ virsh -c qemu:///system list
 Id Name                 State
----------------------------------

wistor@wistor-003:~$ sudo iptables -t nat -L -n
Chain PREROUTING (policy ACCEPT)
target     prot opt source               destination

Chain INPUT (policy ACCEPT)
target     prot opt source               destination

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination

Chain POSTROUTING (policy ACCEPT)
target     prot opt source               destination
MASQUERADE  tcp  --  192.168.122.0/24    !192.168.122.0/24    masq ports: 1024-65535
MASQUERADE  udp  --  192.168.122.0/24    !192.168.122.0/24    masq ports: 1024-65535
MASQUERADE  all  --  192.168.122.0/24    !192.168.122.0/24



wistor@wistor-003:~$ sudo apt-get install virtinst
wistor@wistor-003:~$ cat build_vm.sh
HOSTNAME=vm3
MEMORY=512
CPUS=1
DISK_SIZE=10000
IP=172.16.123.84


sudo virt-install \
-v \
-n $HOSTNAME \
-r $MEMORY \
--disk path=$HOSTNAME.img,bus=virtio,size=4 \
-c ubuntu-11.10-server-amd64.iso \
--accelerate \
--network bridge=br0 \
--connect=qemu:///system \
--virt-type=kvm \
--graphics vnc,listen=0.0.0.0
wistor@wistor-003:~$ sudo ./build_vm.sh
wistor@wistor-003:~$ virsh vncdisplay vm3
:0

2012/03/14 補: 用一個 image 當作 base, 然後 create 出來其他 image 檔
http://jamyy.dyndns.org/blog/2012/02/3594.html

wistor@wistor-001:~$ sudo qemu-img create -b iscsi-server-base.qcow2 -f qcow2 wistor-004.qcow2
Formatting 'wistor-004.qcow2', fmt=qcow2 size=4294967296 backing_file='iscsi-server-base.qcow2' encryption=off cluster_size=0

2012/03/14 補: 把.img 轉成 qcow2

wistor@wistor-001:~$ sudo qemu-img convert -O qcow2 iscsi-server-base.img iscsi-server-base.qcow2

2012/03/15 補: 如何直接 mount qcow2 

wistor@wistor-003:~$ modprobe nbd
wistor@wistor-003:~$ sudo kvm-nbd -c /dev/nbd0 ~/kvm/ubuntu-11.10-3.2-base.qcow2
wistor@wistor-003:~$ sudo mount /dev/nbd0p1 /mnt/kvm
wistor@wistor-003:~$ sudo umount /mnt/kvm
wistor@wistor-003:~$ sudo kvm-nbd -d /dev/nbd0

2012/03/16 補: 如何 boot from network

# 記得要先安裝這個套件
wistor@ubuntu:~/kvm$ sudo apt-get install kvm-pxe
[sudo] password for wistor:
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following NEW packages will be installed:
  kvm-pxe
0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded.
Need to get 128 kB of archives.
After this operation, 201 kB of additional disk space will be used.
Get:1 http://us.archive.ubuntu.com/ubuntu/ oneiric/universe kvm-pxe all 5.4.4-7ubuntu3 [128 kB]
Fetched 128 kB in 2s (58.7 kB/s)
Selecting previously deselected package kvm-pxe.
(Reading database ... 71450 files and directories currently installed.)
Unpacking kvm-pxe (from .../kvm-pxe_5.4.4-7ubuntu3_all.deb) ...
Setting up kvm-pxe (5.4.4-7ubuntu3) ...

# 在  內加上 network 選項, 如果需要 bootmenu 就再加上設定
wistor@ubuntu:~/kvm$ sudo cat /etc/libvirt/qemu/ubuntu-11.10-3.2-base.xml | grep -A 10 os
  
    hvm





Reference:
http://www.howtoforge.com/virtualization-with-kvm-on-ubuntu-10.10


Console problem
http://serverfault.com/questions/338770/kvm-on-ubuntu-console-connection-displays-nothing

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