kvm错误整理

一、启动虚拟机​Connection reset by peer

# virsh start vmhost1
error: Failed to start domain vmhost1
error: Unable to read from monitor: Connection reset by peer

在虚拟机运行过程中关闭宿主服务器就有可能导致这种情况出现，由于宿主服务器中的kvm虚拟机控制器与安装在kvm中的虚拟机会话被异常重置，所以我们可以如下解决：

# virsh managedsave-remove vmhost1
# virsh start vmhost1

如果启动查看/var/log/libvirt/qemu/vmhost1.log下log还报如下错误：

Cannot set up guest memory 'pc.ram': Cannot allocate memory

这个问题可能是分配给vmhost1分配的内存过大（甚至超过的物理主机的内存大小），或者可能是宿主机没有足够的内存分配给此虚拟机，导致无法启动！

二、重Define虚拟机时无/usr/bin/kvm

error: Failed to define domain from hostname.xml
error: Cannot find QEMU binary /usr/bin/kvm: No such file or directory

解决方法：

# ln -s /usr/libexec/qemu-kvm /usr/bin/kvm

三、error: internal error process exited while connecting to monitor

# virsh start vmhost1  

error: Failed to start domain vmhost1
error: internal error process exited while connecting to monitor: kvm: -drive file=/dev/sp1368155439693/v1368544020461,if=none,id=drive-virtio-disk0,format=qcow2: could not open disk image /dev/sp1368155439693/v1368544020461: Invalid argument

分析：镜像格式错误，用qemu-img info 检查镜像和xml配置文件中指定的type是否一致！

四、Unable to load library 'virt': libvirt.so

Unable to load library 'virt': libvirt.so: cannot open shared object file: No such file or directory

Linux下解决：
      ln -s /usr/lib/libvirt.so.0   /usr/lib/libvirt.so

windows下解决：
      将libvirt-0.dll改名为virt.dll

五、error: Refusing to undefine while domain managed save image exists

# virsh undefine vmhost1
error: Refusing to undefine while domain managed save image exists
http://www.redhat.com/archives/libvir-list/2011-July/msg01219.html

解决方法：virsh undefine $domain  --managed-save

六、启动libvirtd进程出错

# /usr/local/sbin/libvirtd -d -l --config /usr/local/etc/libvirt/libvirtd.conf （编译安装的启动方式）

error：/usr/local/sbin/libvirtd: initialization failed
try to install libpcap-devel RPM and rebuild libvirt  http://comments.gmane.org/gmane.comp.emulators.libvirt/58218

apt-get install libpcap-dev
上面的方法好像都没有效果，但是尝试了http://wiki.libvirt.org/page/The_daemon_cannot_be_started说的，把配置文件里的
listen_tls = 0注释取消（更奇怪的问题，在我的客户端链接不对）

七、启动虚拟机报错

# virsh start vmhost1
error: Failed to start domain vmhost1
error: internal error process exited while connecting to monitor: Could not access KVM kernel module: No such file or directory
failed to initialize KVM: No such file or directory
No accelerator found!

上面的提示信息就是因为QEMU在初始化阶段因为无法找到kvm内核模块。

# modprobe kvm   #载入指定的模块

重启电脑，进入bios界面，设置advance选项里面的virtualization标签为Enabled

通过命令 lsmod | grep kvm    #显示已载入的模块

八、虚拟机迁移

# virsh migrate --live 1 qemu+tcp://192.168.0.121 --p2p --tunnelled --unsafe 
error: operation failed: Failed to connect to remote libvirt URI qemu+tcp://192.168.0.121（在URI后面加上/system，‘system’相当于root用户的访问权限)

#virsh migrate --live 2 qemu+tcp://192.168.0.121/system --p2p --tunnelled
 error: Unsafe migration: Migration may lead to data corruption if disks use cache != none（加上--unsafe参数）

#virsh migrate --live 2 qemu+tcp://192.168.0.121/system --p2p --tunnelled --unsafe 
error: Timed out during operation: cannot acquire state change lock (启动虚拟机有时也会遇此错误）,需要重启libvirtd进程

九、virsh

error: Failed to connect socket to '/var/run/libvirt/libvirt-sock': Connection refused(libvirtd 进程没有启动，libvirtd是一个监听客户端请求的进程）

# virsh -c qemu:///system list
error: Failed to connect socket to '/var/run/libvirt/libvirt-sock': Permission denied
error: failed to connect to the hypervisor
（当前用户没有权限，修改/etc/libvirt/libvirtd.conf,unix_sock_rw_perms = 0777,使所有用户都有权限读写）