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 existshttp://www.redhat.com/archives ... .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/gman ... 58218apt-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/T ... arted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）
