cluster size and metadata cache

disk.py

@@ -40,7 +40,7 @@ class Disk(object):
     CREATE_FORMATS = ['qcow2', 'raw']
 
     def __init__(self, dir, name, format, type, size,
-                 base_name, actual_size=0, cache_size=0):
+                 base_name, base_dir = None, actual_size=0, cluster_size=64):
         # TODO: tests
         self.name = name
         self.dir = os.path.realpath(dir)
@@ -56,6 +56,8 @@ class Disk(object):
             self.size = None
         self.actual_size = actual_size
         self.base_name = base_name
+        self.base_dir = base_dir if base_dir is not None else self.dir
+        self.cluster_size = cluster_size
 
     @property
     def checksum(self, blocksize=65536):
@@ -94,7 +96,7 @@ class Disk(object):
 
     def get_base(self):
         """Get absolute path for disk's base image."""
-        return os.path.realpath(self.dir + '/' + self.base_name)
+        return os.path.realpath(self.base_dir + '/' + self.base_name)
 
     def __str__(self):
         return '%s %s %s %s' % (self.get_path(), self.format,
@@ -169,6 +171,7 @@ class Disk(object):
         cmdline = ['qemu-img',
                    'create',
                    '-f', self.format,
+                   '-o', f"cluster_size={int(self.cluster_size)}K",
                    self.get_path(),
                    str(self.size)]
         logging.info("Create file: %s " % cmdline)