diff --git a/opennebula.sh b/opennebula.sh
index d2af466..94802c2 100755
--- a/opennebula.sh
+++ b/opennebula.sh
@@ -196,9 +196,19 @@ ssh root@$play_host 'cat /var/lib/one/.ssh/authorized_keys; true' >> tmp$$
 cat tmp$$ | sort | uniq | ssh root@$play_host 'cat > /var/lib/one/.ssh/authorized_keys'
 rm tmp$$
 
-# Add a host to OpenNebula
+# Add a host to OpenNebula and set reserved memory to 16G
 ssh root@$play_host <<EOF
 set -e -x
 service libvirtd restart
-onehost list | grep $play_host || onehost create $play_host -i kvm -v kvm
+host_name=
+export \$(onehost show -x $play_host | /var/lib/one/remotes/datastore/xpath.rb \
+    "concat('host_name=', /HOST/NAME/text(), ' host_mem=', /HOST/TEMPLATE/RESERVED_MEM/text())" | tr '\0' '\n')
+if [ -z "\$host_name" ]; then
+    onehost create $play_host -i kvm -v kvm
+fi
+if [ "\$host_mem" != "16777216" ]; then
+    echo 'RESERVED_MEM="16777216"' > tmp$$
+    onehost update -a $play_host tmp$$
+    rm tmp$$
+fi
 EOF