Description of problem:

During installation of self hosted engine via RHV Hypervisor 7.2  if /var/tmp is low on disk space an alternate path is requested to be entered in the dialogue box. This path fails during install if the vdsm:kvm user/group doesn't have ownership or RW permission. Hence it needs to be added as a note in the installation documentation. 

Version-Release number of selected component (if applicable):


How reproducible:


Steps to Reproduce:
1. Install Self hosted engine via cockpit

2. At the point were it requests for the below 
" Select disk for the boot device type, and then specify the path to the RHV-M Virtual Appliance. If the /var/tmp directory does not have enough space, specify a different directory.  "

3. Select an alternate path under /usr or /tmp 

Actual results:
Fails with permission denied errors 

2016-08-26 13:44:03 DEBUG otopi.plugins.gr_he_common.vm.boot_disk plugin.execute:926 execute-output: ('/bin/sudo', '-u', 'vdsm', '-g', 'kvm', '/bin/qemu-img', 'info', '--output', 'json', '/root/tmp/tmpXcxmgO') stderr:
qemu-img: Could not open '/root/tmp/tmpXcxmgO': Could not open '/root/tmp/tmpXcxmgO': Permission denied


Expected results: 

Add NOTE in installation to change permission of the folder .

Additional info: