Problem solved.
The cause of the problem was really in the fact that there was no global proxy settings in yum.conf
Thank you all
!
 
14.09.2016, 13:24, "aleksey.maksimov@it-kb.ru" <aleksey.maksimov@it-kb.ru>:
Hmm..I'll try.
How can I call the forced update checking process for oVirt, as well as it happens every night ?
 
14.09.2016, 13:05, "Gianluca Cecchi" <gianluca.cecchi@gmail.com>:
On Wed, Sep 14, 2016 at 10:40 AM, <aleksey.maksimov@it-kb.ru> wrote:
Yesterday I installed the all updates to hosts and Hosted Engine (and now I have oVirt Engine Version: 4.0.3-1.el7.centos)
But the problem still persists.

==>>> Is this happening consistently or randomly?

Consistently. every night.

==>>> Do you have any proxy server defined?

Yes. I add to end of ~/.bash_profile (for root) three lines:

export https_proxy=http://s-MY01-Linux-Upd:Passw0rd@KOM-AD01-GWCLU.holding.com:3128/
export http_proxy=http://s-MY01-Linux-Upd:Passw0rd@KOM-AD01-GWCLU.holding.com:3128/
export ftp_proxy=http://s-MY01-Linux-Upd:Passw0rd@KOM-AD01-GWCLU.holding.com:3128/
 
 
Why not using global proxy config in yum.conf?
https://wiki.centos.org/TipsAndTricks/YumAndRPM#head-ea1fc5d78f578114f4843e57627ebae9cc4fcb5a
 
eventually changing permissions of yum.conf if passowrd is to be kept secret.... (it seems that by default is 644)