diff --git a/administration.md b/administration.md
index 83b706693..21fecc5e6 100644
--- a/administration.md
+++ b/administration.md
@@ -81,4 +81,7 @@ Thanks to Xen Storage Motion, it's easy to move a VM disk from a storage to anot
 
 ### Adjusting resources
 
-You can edit your VM RAM or CPUs in live, like you edit a VM name or description. But there is some XenServer limitations and configuration not exposed directly in Xen Orchestra.
\ No newline at end of file
+You can edit your VM RAM or CPUs in live, like you edit a VM name or description. But there is some XenServer limitations and configuration not exposed directly in Xen Orchestra:
+
+* each VM has a vCPU maximum number. This value can't be change while the VM is running. You can reduce the number of vCPUs, but can't assign more than max. In XO, while your VM is halted, allow the max vCPUs you would need, then boot it. Now you can reduce it and then expand it later to this maximum.
+* the same limitation apply for the RAM.
\ No newline at end of file