diff --git a/xCAT-test/autotest/testcase/installation/ubuntu_diskless_installation_p8le b/xCAT-test/autotest/testcase/installation/ubuntu_diskless_installation_p8le
index 29e0ce3f3..fa08387d9 100644
--- a/xCAT-test/autotest/testcase/installation/ubuntu_diskless_installation_p8le
+++ b/xCAT-test/autotest/testcase/installation/ubuntu_diskless_installation_p8le
@@ -4,7 +4,8 @@ stop=yes
 
 cmd:copycds $$ISO
 check:rc==0
-cmd:if [[ "__GETNODEATTR($$CN,arch)__" != "ppc64" ]];then chdef -t node -o $$CN vmstorage=dir:///var/lib/libvirt/images/ && rmvm $$CN -f  &&  mkvm $$CN ; fi
+cmd:if [[ "__GETNODEATTR($$CN,arch)__" != "ppc64" ]];then chdef -t node -o $$CN vmstorage=dir:///var/lib/libvirt/images/ && rmvm $$CN -f -p &&  mkvm $$CN -s 20G ; fi
+check:rc==0
 cmd:makedns -n
 check:rc==0
 cmd:makedhcp -n