Lack of Ram, not a problem. Each host has 128GB. someone forced the hosts to use 608MB. I changed them last night per Citrix document, but set it to use 3G. See if that solves the problem. Was hitting less than 20MB free during normal operations, that is bad. Now it is not.
http://support.citrix.com/article/CTX134951 --should be using between 1024 MB and 4096 MB.
per
Instructions
To configure the dom0 memory, complete the following procedure:
On the XenServer host, open a local shell and log on as root.
Enter the following command:
/opt/xensource/libexec/xen-cmdline --set-xen dom0_mem=<nn>M,max:<nn>M
Note: <nn> represents the memory in megabytes, to be allocated to dom0. This value should be between 1024 and 4096, depending on the number of VMs that are expected to run and the total memory of the host. A higher value results in less memory being available to the VMs.
Example : /opt/xensource/libexec/xen-cmdline --set-xen dom0_mem=4096M,max:4096M
Note: The above command will set the dom0 memory to 4GB or 4096 MB.
User-added image
Reboot the XenServer host using XenCenter or reboot command on the console.
After the host is rebooted, run the command free on the console to verify the new memory settings.