diff --git a/compute/src/main/java/org/zstack/compute/vm/VmInstanceManagerImpl.java b/compute/src/main/java/org/zstack/compute/vm/VmInstanceManagerImpl.java
index b99e894dfa6..807a8a84e40 100755
--- a/compute/src/main/java/org/zstack/compute/vm/VmInstanceManagerImpl.java
+++ b/compute/src/main/java/org/zstack/compute/vm/VmInstanceManagerImpl.java
@@ -2317,7 +2317,11 @@ public List<Quota> reportQuota() {
                         diskOfferingUuids.addAll(msg.getDataDiskOfferingUuids());
                     }
                     if (imgType == ImageConstant.ImageMediaType.RootVolumeTemplate) {
-                        allVolumeSizeAsked += imgSize;
+                        if (msg.getRootDiskOfferingUuid() != null) {
+                            diskOfferingUuids.add(msg.getRootDiskOfferingUuid());
+                        } else {
+                            allVolumeSizeAsked += imgSize;
+                        }
                     } else if (imgType == ImageConstant.ImageMediaType.ISO) {
                         if (msg.getRootDiskOfferingUuid() != null) {
                             diskOfferingUuids.add(msg.getRootDiskOfferingUuid());
diff --git a/compute/src/main/java/org/zstack/compute/vm/VmQuotaOperator.java b/compute/src/main/java/org/zstack/compute/vm/VmQuotaOperator.java
index d4f6676a70c..52e10ec6cfd 100644
--- a/compute/src/main/java/org/zstack/compute/vm/VmQuotaOperator.java
+++ b/compute/src/main/java/org/zstack/compute/vm/VmQuotaOperator.java
@@ -523,7 +523,11 @@ private void check(APICreateVmInstanceMsg msg, Map<String, Quota.QuotaPair> pair
             diskOfferingUuids.addAll(msg.getDataDiskOfferingUuids());
         }
         if (imgType == ImageConstant.ImageMediaType.RootVolumeTemplate) {
-            allVolumeSizeAsked += imgSize;
+            if (msg.getRootDiskOfferingUuid() != null) {
+                diskOfferingUuids.add(msg.getRootDiskOfferingUuid());
+            } else {
+                allVolumeSizeAsked += imgSize;
+            }
         } else if (imgType == ImageConstant.ImageMediaType.ISO) {
             if (msg.getRootDiskOfferingUuid() != null) {
                 diskOfferingUuids.add(msg.getRootDiskOfferingUuid());