On Wed, Sep 10, 2014 at 11:57:05PM +0300, Mohyedeen Nazzal wrote:
Hi All, I have noticed that there is a huge difference between memory reading obtained from top or free commands, and values displayed on ovirt engine. "Host "
Example: Engine Version : *ovirt-engine-3.4.3-1.el6.noarch* *OS: Centos 6.5_x86_64*
*Used Memory:* *from free:* [root@oVirt ~]# free total used free shared buffers cached Mem: 65890412 65609864 280548 0 305408 53759412
from Egnine Webpage:
only 12G is being used.
Is there an explanation for this ?
It's a Linux thing. When a file is opened, it is mapped into memory, but when it is closed Linux does not evict it before memory is released again. Thus, a long-running active host reaches 0 free mem sooner than later. For oVirt GUI, we found this misleading - there, "free" means "how much memory is available for new VMs to use". Therefore oVirt reports "buffred" and "cached" memory as free, too.