When /var/log is full, no notice will show up in xencenter as before when root partition was full

I have upgraded an XenServer 6.5 pool to 7.0 which is hosting GRID cards.
After the upgrade some hardware related issues create a lot of dump snips in the logs and log rotate is not able to clean up space fast enough.
This leads to 100% usage of /var/log and with this to the same issues we had when root partition was full in earlier XS versions.

XenCenter is not reporting about "root partition full" or anything like this.
administrators were not aware of this until the hosts rebooted unexpected.
please add an trigger on /var/log partition too, to make adminsitrators aware.