add copy backup level

README.md

@@ -54,8 +54,14 @@ consistency by creating the bitmap and backup within one QMP transaction.
 
 Multiple disks attached to the virtual machine are backed up concurrently.
 
-Bitmaps will be added with persistent option flag, which means they are stored
-permanently and are available between virtual machine shutdowns.
+During full and incremental backup, bitmaps will be created with `persistent
+option flag`. This means QEMU attempts to store them in the QCOW images, so
+they are available between virtual machine shutdowns. The attached QCOW images
+must be in qcow(v3) format, for this to work.
+
+If you cant convert your QCOW images to newer formats, you still can use the
+backup mode `copy`: it allows to execute a complete full backup but no further
+incremental backups.
 
 Second step is to change some data within your virtual machine and let
 *qmpbackup* create an incremental backup for you, this works by:

libqmpbackup/qmpcommon.py

@@ -49,6 +49,9 @@ def prepare_transaction(self, devices, level, backupdir):
             prefix = "INC"
             sync = "incremental"
 
+        if level == "copy":
+            self.log.info("Copy backup: no bitmap will be created.")
+
         actions = []
         files = []
         for device in devices:
@@ -64,14 +67,16 @@ def prepare_transaction(self, devices, level, backupdir):
             if not device.has_bitmap and level == "full":
                 self.log.debug("Creating new bitmap")
                 actions.append(
-                    self.transaction_bitmap_add(device.node, bitmap, persistent=True)
+                    self.transaction_bitmap_add(
+                        device.node, bitmap, persistent=True
+                    )
                 )
 
             if device.has_bitmap and level == "full":
                 self.log.debug("Clearing existing bitmap")
                 actions.append(self.transaction_bitmap_clear(device.node, bitmap))
 
-            if level == "full":
+            if level in ("full", "copy"):
                 actions.append(
                     self.transaction_action(
                         "drive-backup",

qmpbackup

@@ -94,7 +94,7 @@ async def main():
     parser_backup.set_defaults(which="backup")
     parser_backup.add_argument(
         "--level",
-        choices=["full", "inc", "auto"],
+        choices=["copy", "full", "inc", "auto"],
         type=str,
         help="backup level",
         required=True,