libvirt错误总结
virsh start vm1368544020451:
error: Failed to start domain vm1368544020451
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
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。
error: Failed to start domain vm0
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。
sudo 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
虚拟机迁移：
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)
error: Unsafe migration: Migration may lead to data corruption if disks use cache != none（加上--unsafe参数）
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
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）
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）
启动虚拟机：Connection reset by peer
virsh start vm1355991767186
error: Failed to start domain vm1355991767186
error: Unable to read from monitor: Connection reset by peer
还有可能是这样提示：
error: internal error process exited while connecting to monitor: Failed to allocate 16332619776 B: Cannot allocate memory
这个问题可能是因为为VM分配的内存过大（甚至超过的物理主机的内存大小）
Unable to load library 'virt': libvirt.so: cannot open shared object file: No such file or directory
# virsh undefine vm1354695894990
error: Refusing to undefine while domain managed save image exists
http://www.redhat.com/archives/libvir-list/2011-July/msg01219.html
managedsave