Product : Citrix, XenServer/7.1, Standard
Feature : Max RAM per VM, VM Config , Hypervisor
Content Owner:  Roman Macek
Summary
1.5TB
Details
A maximum of 1.5TB is supported for guest Oss, actual number varies greatly with guest OS version so please check for specific guest support.

The maximum amount of physical memory addressable by your operating system varies. Setting the memory to a level greater than the operating system supported limit, may lead to performance issues within your guest. Some 32-bit Windows operating systems can support more than 4 GB of RAM through use of the physical address extension (PAE) mode. The limit for 32-bit PV Virtual Machines is 64GB. Please consult your guest operating system Administrators Guide and the XenServer Virtual Machine Users Guide for more details.