virt-install could not open disk image

简介

本文介绍如何解决因qemu的用户和组配置错误导致virt-install无法读取磁盘映像问题。

问题描述

在使用virt-install安装虚拟机时，出现无法读取ISO磁盘映像问题，日志如下：

 [root@CentOS65 ~]# virt-install --name=centos65 --ram=2048 --vcpu=1 --os-type=linux --hvm --cdrom=/root/CentOS-6.5-x86_64-minimal.iso --file=/home/kvm/centos65.img --file-size=10 --bridge=br0 --vnc --vncport=5920

 Starting install...
 Creating storage file centos65.img                                                                           |  10 GB     00:00
 ERROR    internal error Process exited while reading console log output: char device redirected to /dev/pts/4
 2016-01-27T08:56:58.986952Z qemu-kvm: -drive file=/root/CentOS-6.5-x86_64-minimal.iso,if=none,media=cdrom,id=drive-ide0-1-0,readonly=on,format=raw: could not open disk image /root/CentOS-6.5-x86_64-minimal.iso: Permission denied

 Domain installation does not appear to have been successful.
 If it was, you can restart your domain by running:
   virsh --connect qemu:///system start centos65
 otherwise, please restart your installation.

问题分析与解决方案

上述“Permission denied”问题，属于用户权限问题，查看/etc/libvirt/qemu.conf配置文件，查找到如下相关的配置项：

 # The user for QEMU processes run by the system instance. It can be
 # specified as a user name or as a user id. The qemu driver will try to
 # parse this value first as a name and then, if the name doesn't exist,
 # as a user id.
 #
 # Since a sequence of digits is a valid user name, a leading plus sign
 # can be used to ensure that a user id will not be interpreted as a user
 # name.
 #
 # Some examples of valid values are:
 #
 #       user = "qemu"   # A user named "qemu"
 #       user = "+0"     # Super user (uid=0)
 #       user = "100"    # A user named "100" or a user with uid=100
 #
 #user = "root"

 # The group for QEMU processes run by the system instance. It can be
 # specified in a similar way to user.
 #group = "root"

需要配置qemu进程的用户和组相关配置，可根据自己的实际情况进行修改，作者将user和group都设置成root:

 # The user for QEMU processes run by the system instance. It can be
 # specified as a user name or as a user id. The qemu driver will try to
 # parse this value first as a name and then, if the name doesn't exist,
 # as a user id.
 #
 # Since a sequence of digits is a valid user name, a leading plus sign
 # can be used to ensure that a user id will not be interpreted as a user
 # name.
 #
 # Some examples of valid values are:
 #
 #       user = "qemu"   # A user named "qemu"
 #       user = "+0"     # Super user (uid=0)
 #       user = "100"    # A user named "100" or a user with uid=100
 #
 user = "root"

 # The group for QEMU processes run by the system instance. It can be
 # specified in a similar way to user.
 group = "root"

配置修改完成后，需要重启libvirtd服务

 [root@CentOS65 ~]# service libvirtd restart