RHEL7 USB installation problem and solving        

Encountered quite a few problems while install the RHEL7, with the Windows system already installed.

Problem 1:/dev/root does not exist

Downloaded the Redhat 7 ISO file and generate the bootable USB drive by using software 'rufus-1.4.9.exe'.

in the installation menu, press tab key, and enter to modify the install command, change the

“hd:……“ to "hd:/devsdb#"(from hd: until the end exact replace, sdb is the usb drive you have, maybe is sdc, or sdb, '#' normally is '1'), and then press enter, problem solved.

第一次进入安装菜单选项后，按下tab键，修改"hd:...."为“hd:/dev/sdb1 LABEL....”,这里sdb表示usb盘，1表示usb的第一个分区，常常usb只有一个分区。。当然，可能是sdc，或者sdd，取决于你的计算机中有几个物理硬盘。

如果启动时，快速按F8（对华硕主板），直接选择从usb优盘启动，就没有以上问题了。以上问题是在在efi中选择从USB优盘启动，就会出现这个，这是一个BUG。当然，如果是thinkpad笔记本，按键又不一样，自己在网上查一下。

Problem 2: cannot boot both system

modified the /boot/grub/grub.conf (for RHEL6), changed the (hd1,0) to (hd0,0), it is starting from 0, the value 1 comes from the USB drive bootable drive.

Problem 3, how to change the sequence on the in Grub of RHEL6

change the default from 0 to 1 in /boot/grub/grub.conf, 0 will be the linux at defalt, 1 will be windows be default.

Problem 4: only boot into RHEL7, cannot see the dual boot interface in Grub2.

Create the file and add the following

   /etc/grub.d/10_windows7     #! /bin/bash     echo "Adding Windows7 entry to grub"     cat << EOF     menuentry "Windows" {     set root=hd0(0,1)     chainloader +1      }     EOF

Adjust hd0(0,1) accordingly. You can use hd0(0,1) if windows is installed on /dev/sda1

2. chmod +x /etc/grub.d/10_windows7

3. grub2-mkconfig -o /boot/grub2/grub.cfg

Problem 5, change the boot priority in Grub2 of RHEL7

change the name of /etc/grub.d/10_windows7 to 09_windows7, 09 has lower number as linux file (in my Linux system it's 10_linux, change to 09 is smaller than 10), has higher priority.

then execute 'grub2-mkconfig -o /boot/grub2/grub.cfg', reboot, the system will default as Windows to boot.