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
