RHEVM : Critical, Low Diskspace warnings for /var/log for hypervisor

RHEVM 3.1.0-50

RHEVH 20130318

Can anyone help me with this one ?   I've raised a support ticket but fear I may run out of diskspace beforehand !

RHEVM is reporting "Critical, Low disk space" on /var/log for a hypervisor.

 I would like to understand how to clear this down and stop the alerts.

I have seen knowledge base article (https://access.redhat.com/site/solutions/289583) but it is not relevant as we are already running the vdsm package with the supposed fix (vdsm-4.10.2-1.6.el6). 

It tells me I only have 50M of space left on /var/log"

Moreover, I'm slightly confused because /var/log appears to be both a memory based (tmpfs) filesystem and also a logical volume.  Which is it,  or is it somehow both ?   I'm probably misunderstanding something.

 Either way, df -h on /var/log shows 1.8G used of 2.0G  , but du -sh of /var/log show only 290M.

 [root@rhphyp03a log]# df -h /var/log

Filesystem            Size  Used Avail Use% Mounted on

-                     2.0G  1.8G   92M  96% /var/log

[root@rhphyp03a log]# pwd

/var/log

[root@rhphyp03a log]# du -sh

290M    .

 [root@rhphyp03a log]# cat /proc/mounts | grep "/var/log"

none /var/log tmpfs rw,rootcontext=system_u:object_r:var_lib_t:s0,seclabel,relatime 0 0 /dev/mapper/HostVG-Logging /var/log ext4 rw,seclabel,noatime,barrier=1,stripe=64,data=ordered 0 0"