Implement BuildHooksEnv for NoHooksLU

[ganeti-local] / lib / config.py

diff --git a/lib/config.py b/lib/config.py
index b8adc84..712f599 100644 (file)
--- a/lib/config.py
+++ b/lib/config.py
@@ -43,19 +43,24 @@ from ganeti import constants
 from ganeti import rpc
 from ganeti import objects
 from ganeti import serializer
 from ganeti import rpc
 from ganeti import objects
 from ganeti import serializer

-from ganeti import ssconf

 
 
 _config_lock = locking.SharedLock()
 
 
 
 
 _config_lock = locking.SharedLock()
 
 

-def ValidateConfig():
-  sstore = ssconf.SimpleStore()
+def _ValidateConfig(data):
+  """Verifies that a configuration objects looks valid.

 
 

-  if sstore.GetConfigVersion() != constants.CONFIG_VERSION:
+  This only verifies the version of the configuration.
+
+  @raise errors.ConfigurationError: if the version differs from what
+      we expect
+
+  """
+  if data.version != constants.CONFIG_VERSION:

     raise errors.ConfigurationError("Cluster configuration version"
                                     " mismatch, got %s instead of %s" %
     raise errors.ConfigurationError("Cluster configuration version"
                                     " mismatch, got %s instead of %s" %

-                                    (sstore.GetConfigVersion(),
+                                    (data.version,

                                      constants.CONFIG_VERSION))
 
 
                                      constants.CONFIG_VERSION))
 
 

@@ -67,9 +72,6 @@ class ConfigWriter:
     self.write_count = 0
     self._lock = _config_lock
     self._config_data = None
     self.write_count = 0
     self._lock = _config_lock
     self._config_data = None

-    self._config_time = None
-    self._config_size = None
-    self._config_inode = None

     self._offline = offline
     if cfg_file is None:
       self._cfg_file = constants.CLUSTER_CONF_FILE
     self._offline = offline
     if cfg_file is None:
       self._cfg_file = constants.CLUSTER_CONF_FILE

@@ -77,11 +79,14 @@ class ConfigWriter:
       self._cfg_file = cfg_file
     self._temporary_ids = set()
     self._temporary_drbds = {}
       self._cfg_file = cfg_file
     self._temporary_ids = set()
     self._temporary_drbds = {}

+    self._temporary_macs = set()

     # Note: in order to prevent errors when resolving our name in
     # _DistributeConfig, we compute it here once and reuse it; it's
     # better to raise an error before starting to modify the config
     # file than after it was modified
     self._my_hostname = utils.HostInfo().name
     # Note: in order to prevent errors when resolving our name in
     # _DistributeConfig, we compute it here once and reuse it; it's
     # better to raise an error before starting to modify the config
     # file than after it was modified
     self._my_hostname = utils.HostInfo().name

+    self._last_cluster_serial = -1
+    self._OpenConfig()

 
   # this method needs to be static, so that we can call it on the class
   @staticmethod
 
   # this method needs to be static, so that we can call it on the class
   @staticmethod

@@ -98,7 +103,6 @@ class ConfigWriter:
     This should check the current instances for duplicates.
 
     """
     This should check the current instances for duplicates.
 
     """

-    self._OpenConfig()

     prefix = self._config_data.cluster.mac_prefix
     all_macs = self._AllMACs()
     retries = 64
     prefix = self._config_data.cluster.mac_prefix
     all_macs = self._AllMACs()
     retries = 64

@@ -107,11 +111,12 @@ class ConfigWriter:
       byte2 = random.randrange(0, 256)
       byte3 = random.randrange(0, 256)
       mac = "%s:%02x:%02x:%02x" % (prefix, byte1, byte2, byte3)
       byte2 = random.randrange(0, 256)
       byte3 = random.randrange(0, 256)
       mac = "%s:%02x:%02x:%02x" % (prefix, byte1, byte2, byte3)

-      if mac not in all_macs:
+      if mac not in all_macs and mac not in self._temporary_macs:

         break
       retries -= 1
     else:
       raise errors.ConfigurationError("Can't generate unique MAC")
         break
       retries -= 1
     else:
       raise errors.ConfigurationError("Can't generate unique MAC")

+    self._temporary_macs.add(mac)

     return mac
 
   @locking.ssynchronized(_config_lock, shared=1)
     return mac
 
   @locking.ssynchronized(_config_lock, shared=1)

@@ -122,15 +127,31 @@ class ConfigWriter:
     check for potential collisions elsewhere.
 
     """
     check for potential collisions elsewhere.
 
     """

-    self._OpenConfig()

     all_macs = self._AllMACs()
     all_macs = self._AllMACs()

-    return mac in all_macs
+    return mac in all_macs or mac in self._temporary_macs
+
+  @locking.ssynchronized(_config_lock, shared=1)
+  def GenerateDRBDSecret(self):
+    """Generate a DRBD secret.
+
+    This checks the current disks for duplicates.

 
 

-  def _ComputeAllLVs(self):
+    """
+    all_secrets = self._AllDRBDSecrets()
+    retries = 64
+    while retries > 0:
+      secret = utils.GenerateSecret()
+      if secret not in all_secrets:
+        break
+      retries -= 1
+    else:
+      raise errors.ConfigurationError("Can't generate unique DRBD secret")
+    return secret
+
+  def _AllLVs(self):

     """Compute the list of all LVs.
 
     """
     """Compute the list of all LVs.
 
     """

-    self._OpenConfig()

     lvnames = set()
     for instance in self._config_data.instances.values():
       node_data = instance.MapLVsByNode()
     lvnames = set()
     for instance in self._config_data.instances.values():
       node_data = instance.MapLVsByNode()

@@ -138,6 +159,23 @@ class ConfigWriter:
         lvnames.update(lv_list)
     return lvnames
 
         lvnames.update(lv_list)
     return lvnames
 

+  def _AllIDs(self, include_temporary):
+    """Compute the list of all UUIDs and names we have.
+
+    @type include_temporary: boolean
+    @param include_temporary: whether to include the _temporary_ids set
+    @rtype: set
+    @return: a set of IDs
+
+    """
+    existing = set()
+    if include_temporary:
+      existing.update(self._temporary_ids)
+    existing.update(self._AllLVs())
+    existing.update(self._config_data.instances.keys())
+    existing.update(self._config_data.nodes.keys())
+    return existing
+

   @locking.ssynchronized(_config_lock, shared=1)
   def GenerateUniqueID(self, exceptions=None):
     """Generate an unique disk name.
   @locking.ssynchronized(_config_lock, shared=1)
   def GenerateUniqueID(self, exceptions=None):
     """Generate an unique disk name.

@@ -145,20 +183,16 @@ class ConfigWriter:
     This checks the current node, instances and disk names for
     duplicates.
 
     This checks the current node, instances and disk names for
     duplicates.
 

-    Args:
-      - exceptions: a list with some other names which should be checked
-                    for uniqueness (used for example when you want to get
-                    more than one id at one time without adding each one in
-                    turn to the config file
+    @param exceptions: a list with some other names which should be checked
+        for uniqueness (used for example when you want to get
+        more than one id at one time without adding each one in
+        turn to the config file)

 
 

-    Returns: the unique id as a string
+    @rtype: string
+    @return: the unique id

 
     """
 
     """

-    existing = set()
-    existing.update(self._temporary_ids)
-    existing.update(self._ComputeAllLVs())
-    existing.update(self._config_data.instances.keys())
-    existing.update(self._config_data.nodes.keys())
+    existing = self._AllIDs(include_temporary=True)

     if exceptions is not None:
       existing.update(exceptions)
     retries = 64
     if exceptions is not None:
       existing.update(exceptions)
     retries = 64

@@ -172,12 +206,20 @@ class ConfigWriter:
     self._temporary_ids.add(unique_id)
     return unique_id
 
     self._temporary_ids.add(unique_id)
     return unique_id
 

+  def _CleanupTemporaryIDs(self):
+    """Cleanups the _temporary_ids structure.
+
+    """
+    existing = self._AllIDs(include_temporary=False)
+    self._temporary_ids = self._temporary_ids - existing
+

   def _AllMACs(self):
     """Return all MACs present in the config.
 
   def _AllMACs(self):
     """Return all MACs present in the config.
 

-    """
-    self._OpenConfig()
+    @rtype: list
+    @return: the list of all MACs

 
 

+    """

     result = []
     for instance in self._config_data.instances.values():
       for nic in instance.nics:
     result = []
     for instance in self._config_data.instances.values():
       for nic in instance.nics:

@@ -185,16 +227,86 @@ class ConfigWriter:
 
     return result
 
 
     return result
 

-  @locking.ssynchronized(_config_lock, shared=1)
-  def VerifyConfig(self):
-    """Stub verify function.
+  def _AllDRBDSecrets(self):
+    """Return all DRBD secrets present in the config.
+
+    @rtype: list
+    @return: the list of all DRBD secrets
+

     """
     """

-    self._OpenConfig()
+    def helper(disk, result):
+      """Recursively gather secrets from this disk."""
+      if disk.dev_type == constants.DT_DRBD8:
+        result.append(disk.logical_id[5])
+      if disk.children:
+        for child in disk.children:
+          helper(child, result)

 
     result = []
 
     result = []

+    for instance in self._config_data.instances.values():
+      for disk in instance.disks:
+        helper(disk, result)
+
+    return result
+
+  def _CheckDiskIDs(self, disk, l_ids, p_ids):
+    """Compute duplicate disk IDs
+
+    @type disk: L{objects.Disk}
+    @param disk: the disk at which to start searching
+    @type l_ids: list
+    @param l_ids: list of current logical ids
+    @type p_ids: list
+    @param p_ids: list of current physical ids
+    @rtype: list
+    @return: a list of error messages
+
+    """
+    result = []
+    if disk.logical_id is not None:
+      if disk.logical_id in l_ids:
+        result.append("duplicate logical id %s" % str(disk.logical_id))
+      else:
+        l_ids.append(disk.logical_id)
+    if disk.physical_id is not None:
+      if disk.physical_id in p_ids:
+        result.append("duplicate physical id %s" % str(disk.physical_id))
+      else:
+        p_ids.append(disk.physical_id)
+
+    if disk.children:
+      for child in disk.children:
+        result.extend(self._CheckDiskIDs(child, l_ids, p_ids))
+    return result
+
+  def _UnlockedVerifyConfig(self):
+    """Verify function.
+
+    @rtype: list
+    @return: a list of error messages; a non-empty list signifies
+        configuration errors
+
+    """
+    result = []

     seen_macs = []
     ports = {}
     data = self._config_data
     seen_macs = []
     ports = {}
     data = self._config_data

+    seen_lids = []
+    seen_pids = []
+
+    # global cluster checks
+    if not data.cluster.enabled_hypervisors:
+      result.append("enabled hypervisors list doesn't have any entries")
+    invalid_hvs = set(data.cluster.enabled_hypervisors) - constants.HYPER_TYPES
+    if invalid_hvs:
+      result.append("enabled hypervisors contains invalid entries: %s" %
+                    invalid_hvs)
+
+    if data.cluster.master_node not in data.nodes:
+      result.append("cluster has invalid primary node '%s'" %
+                    data.cluster.master_node)
+
+    # per-instance checks

     for instance_name in data.instances:
       instance = data.instances[instance_name]
       if instance.primary_node not in data.nodes:
     for instance_name in data.instances:
       instance = data.instances[instance_name]
       if instance.primary_node not in data.nodes:

@@ -225,8 +337,14 @@ class ConfigWriter:
           ports[net_port] = []
         ports[net_port].append((instance.name, "network port"))
 
           ports[net_port] = []
         ports[net_port].append((instance.name, "network port"))
 

+      # instance disk verify
+      for idx, disk in enumerate(instance.disks):
+        result.extend(["instance '%s' disk %d error: %s" %
+                       (instance.name, idx, msg) for msg in disk.Verify()])
+        result.extend(self._CheckDiskIDs(disk, seen_lids, seen_pids))
+

     # cluster-wide pool of free ports
     # cluster-wide pool of free ports

-    for free_port in self._config_data.cluster.tcpudp_port_pool:
+    for free_port in data.cluster.tcpudp_port_pool:

       if free_port not in ports:
         ports[free_port] = []
       ports[free_port].append(("cluster", "port marked as free"))
       if free_port not in ports:
         ports[free_port] = []
       ports[free_port].append(("cluster", "port marked as free"))

@@ -242,13 +360,48 @@ class ConfigWriter:
 
     # highest used tcp port check
     if keys:
 
     # highest used tcp port check
     if keys:

-      if keys[-1] > self._config_data.cluster.highest_used_port:
+      if keys[-1] > data.cluster.highest_used_port:

         result.append("Highest used port mismatch, saved %s, computed %s" %
         result.append("Highest used port mismatch, saved %s, computed %s" %

-                      (self._config_data.cluster.highest_used_port,
-                       keys[-1]))
+                      (data.cluster.highest_used_port, keys[-1]))
+
+    if not data.nodes[data.cluster.master_node].master_candidate:
+      result.append("Master node is not a master candidate")
+
+    # master candidate checks
+    mc_now, mc_max = self._UnlockedGetMasterCandidateStats()
+    if mc_now < mc_max:
+      result.append("Not enough master candidates: actual %d, target %d" %
+                    (mc_now, mc_max))
+
+    # node checks
+    for node in data.nodes.values():
+      if [node.master_candidate, node.drained, node.offline].count(True) > 1:
+        result.append("Node %s state is invalid: master_candidate=%s,"
+                      " drain=%s, offline=%s" %
+                      (node.name, node.master_candidate, node.drain,
+                       node.offline))
+
+    # drbd minors check
+    d_map, duplicates = self._UnlockedComputeDRBDMap()
+    for node, minor, instance_a, instance_b in duplicates:
+      result.append("DRBD minor %d on node %s is assigned twice to instances"
+                    " %s and %s" % (minor, node, instance_a, instance_b))

 
     return result
 
 
     return result
 

+  @locking.ssynchronized(_config_lock, shared=1)
+  def VerifyConfig(self):
+    """Verify function.
+
+    This is just a wrapper over L{_UnlockedVerifyConfig}.
+
+    @rtype: list
+    @return: a list of error messages; a non-empty list signifies
+        configuration errors
+
+    """
+    return self._UnlockedVerifyConfig()
+

   def _UnlockedSetDiskID(self, disk, node_name):
     """Convert the unique ID to the ID needed on the target nodes.
 
   def _UnlockedSetDiskID(self, disk, node_name):
     """Convert the unique ID to the ID needed on the target nodes.
 

@@ -268,7 +421,7 @@ class ConfigWriter:
     if disk.logical_id is None and disk.physical_id is not None:
       return
     if disk.dev_type == constants.LD_DRBD8:
     if disk.logical_id is None and disk.physical_id is not None:
       return
     if disk.dev_type == constants.LD_DRBD8:

-      pnode, snode, port, pminor, sminor = disk.logical_id
+      pnode, snode, port, pminor, sminor, secret = disk.logical_id

       if node_name not in (pnode, snode):
         raise errors.ConfigurationError("DRBD device not knowing node %s" %
                                         node_name)
       if node_name not in (pnode, snode):
         raise errors.ConfigurationError("DRBD device not knowing node %s" %
                                         node_name)

@@ -280,9 +433,9 @@ class ConfigWriter:
       p_data = (pnode_info.secondary_ip, port)
       s_data = (snode_info.secondary_ip, port)
       if pnode == node_name:
       p_data = (pnode_info.secondary_ip, port)
       s_data = (snode_info.secondary_ip, port)
       if pnode == node_name:

-        disk.physical_id = p_data + s_data + (pminor,)
+        disk.physical_id = p_data + s_data + (pminor, secret)

       else: # it must be secondary, we tested above
       else: # it must be secondary, we tested above

-        disk.physical_id = s_data + p_data + (sminor,)
+        disk.physical_id = s_data + p_data + (sminor, secret)

     else:
       disk.physical_id = disk.logical_id
     return
     else:
       disk.physical_id = disk.logical_id
     return

@@ -308,7 +461,6 @@ class ConfigWriter:
     if not isinstance(port, int):
       raise errors.ProgrammerError("Invalid type passed for port")
 
     if not isinstance(port, int):
       raise errors.ProgrammerError("Invalid type passed for port")
 

-    self._OpenConfig()

     self._config_data.cluster.tcpudp_port_pool.add(port)
     self._WriteConfig()
 
     self._config_data.cluster.tcpudp_port_pool.add(port)
     self._WriteConfig()
 

@@ -317,7 +469,6 @@ class ConfigWriter:
     """Returns a copy of the current port list.
 
     """
     """Returns a copy of the current port list.
 
     """

-    self._OpenConfig()

     return self._config_data.cluster.tcpudp_port_pool.copy()
 
   @locking.ssynchronized(_config_lock)
     return self._config_data.cluster.tcpudp_port_pool.copy()
 
   @locking.ssynchronized(_config_lock)

@@ -329,8 +480,6 @@ class ConfigWriter:
     highest_used_port).
 
     """
     highest_used_port).
 
     """

-    self._OpenConfig()
-

     # If there are TCP/IP ports configured, we use them first.
     if self._config_data.cluster.tcpudp_port_pool:
       port = self._config_data.cluster.tcpudp_port_pool.pop()
     # If there are TCP/IP ports configured, we use them first.
     if self._config_data.cluster.tcpudp_port_pool:
       port = self._config_data.cluster.tcpudp_port_pool.pop()

@@ -345,37 +494,61 @@ class ConfigWriter:
     self._WriteConfig()
     return port
 
     self._WriteConfig()
     return port
 

-  def _ComputeDRBDMap(self, instance):
+  def _UnlockedComputeDRBDMap(self):

     """Compute the used DRBD minor/nodes.
 
     """Compute the used DRBD minor/nodes.
 

-    Return: dictionary of node_name: dict of minor: instance_name. The
-    returned dict will have all the nodes in it (even if with an empty
-    list).
+    @rtype: (dict, list)
+    @return: dictionary of node_name: dict of minor: instance_name;
+        the returned dict will have all the nodes in it (even if with
+        an empty list), and a list of duplicates; if the duplicates
+        list is not empty, the configuration is corrupted and its caller
+        should raise an exception

 
     """
     def _AppendUsedPorts(instance_name, disk, used):
 
     """
     def _AppendUsedPorts(instance_name, disk, used):

-      if disk.dev_type == constants.LD_DRBD8 and len(disk.logical_id) == 5:
-        nodeA, nodeB, dummy, minorA, minorB = disk.logical_id
-        for node, port in ((nodeA, minorA), (nodeB, minorB)):
-          assert node in used, "Instance node not found in node list"
+      duplicates = []
+      if disk.dev_type == constants.LD_DRBD8 and len(disk.logical_id) >= 5:
+        node_a, node_b, _, minor_a, minor_b = disk.logical_id[:5]
+        for node, port in ((node_a, minor_a), (node_b, minor_b)):
+          assert node in used, ("Node '%s' of instance '%s' not found"
+                                " in node list" % (node, instance_name))

           if port in used[node]:
           if port in used[node]:

-            raise errors.ProgrammerError("DRBD minor already used:"
-                                         " %s/%s, %s/%s" %
-                                         (node, port, instance_name,
-                                          used[node][port]))
-
-          used[node][port] = instance_name
+            duplicates.append((node, port, instance_name, used[node][port]))
+          else:
+            used[node][port] = instance_name

       if disk.children:
         for child in disk.children:
       if disk.children:
         for child in disk.children:

-          _AppendUsedPorts(instance_name, child, used)
+          duplicates.extend(_AppendUsedPorts(instance_name, child, used))
+      return duplicates

 
 

+    duplicates = []

     my_dict = dict((node, {}) for node in self._config_data.nodes)
     my_dict = dict((node, {}) for node in self._config_data.nodes)

-    for (node, minor), instance in self._temporary_drbds.iteritems():
-      my_dict[node][minor] = instance

     for instance in self._config_data.instances.itervalues():
       for disk in instance.disks:
     for instance in self._config_data.instances.itervalues():
       for disk in instance.disks:

-        _AppendUsedPorts(instance.name, disk, my_dict)
-    return my_dict
+        duplicates.extend(_AppendUsedPorts(instance.name, disk, my_dict))
+    for (node, minor), instance in self._temporary_drbds.iteritems():
+      if minor in my_dict[node] and my_dict[node][minor] != instance:
+        duplicates.append((node, minor, instance, my_dict[node][minor]))
+      else:
+        my_dict[node][minor] = instance
+    return my_dict, duplicates
+
+  @locking.ssynchronized(_config_lock)
+  def ComputeDRBDMap(self):
+    """Compute the used DRBD minor/nodes.
+
+    This is just a wrapper over L{_UnlockedComputeDRBDMap}.
+
+    @return: dictionary of node_name: dict of minor: instance_name;
+        the returned dict will have all the nodes in it (even if with
+        an empty list).
+
+    """
+    d_map, duplicates = self._UnlockedComputeDRBDMap()
+    if duplicates:
+      raise errors.ConfigurationError("Duplicate DRBD ports detected: %s" %
+                                      str(duplicates))
+    return d_map

 
   @locking.ssynchronized(_config_lock)
   def AllocateDRBDMinor(self, nodes, instance):
 
   @locking.ssynchronized(_config_lock)
   def AllocateDRBDMinor(self, nodes, instance):

@@ -386,10 +559,17 @@ class ConfigWriter:
     multiple minors. The result is the list of minors, in the same
     order as the passed nodes.
 
     multiple minors. The result is the list of minors, in the same
     order as the passed nodes.
 

+    @type instance: string
+    @param instance: the instance for which we allocate minors
+

     """
     """

-    self._OpenConfig()
+    assert isinstance(instance, basestring), \
+           "Invalid argument '%s' passed to AllocateDRBDMinor" % instance

 
 

-    d_map = self._ComputeDRBDMap(instance)
+    d_map, duplicates = self._UnlockedComputeDRBDMap()
+    if duplicates:
+      raise errors.ConfigurationError("Duplicate DRBD ports detected: %s" %
+                                      str(duplicates))

     result = []
     for nname in nodes:
       ndata = d_map[nname]
     result = []
     for nname in nodes:
       ndata = d_map[nname]

@@ -397,6 +577,7 @@ class ConfigWriter:
         # no minors used, we can start at 0
         result.append(0)
         ndata[0] = instance
         # no minors used, we can start at 0
         result.append(0)
         ndata[0] = instance

+        self._temporary_drbds[(nname, 0)] = instance

         continue
       keys = ndata.keys()
       keys.sort()
         continue
       keys = ndata.keys()
       keys.sort()

@@ -407,40 +588,120 @@ class ConfigWriter:
         minor = keys[-1] + 1
       else:
         minor = ffree
         minor = keys[-1] + 1
       else:
         minor = ffree

-      result.append(minor)
+      # double-check minor against current instances
+      assert minor not in d_map[nname], \
+             ("Attempt to reuse allocated DRBD minor %d on node %s,"
+              " already allocated to instance %s" %
+              (minor, nname, d_map[nname][minor]))

       ndata[minor] = instance
       ndata[minor] = instance

-      assert (nname, minor) not in self._temporary_drbds, \
-             "Attempt to reuse reserved DRBD minor"
-      self._temporary_drbds[(nname, minor)] = instance
+      # double-check minor against reservation
+      r_key = (nname, minor)
+      assert r_key not in self._temporary_drbds, \
+             ("Attempt to reuse reserved DRBD minor %d on node %s,"
+              " reserved for instance %s" %
+              (minor, nname, self._temporary_drbds[r_key]))
+      self._temporary_drbds[r_key] = instance
+      result.append(minor)

     logging.debug("Request to allocate drbd minors, input: %s, returning %s",
                   nodes, result)
     return result
 
     logging.debug("Request to allocate drbd minors, input: %s, returning %s",
                   nodes, result)
     return result
 

-  @locking.ssynchronized(_config_lock)
-  def ReleaseDRBDMinors(self, instance):
+  def _UnlockedReleaseDRBDMinors(self, instance):

     """Release temporary drbd minors allocated for a given instance.
 
     """Release temporary drbd minors allocated for a given instance.
 

-    This should be called on both the error paths and on the success
-    paths (after the instance has been added or updated).
-

     @type instance: string
     @param instance: the instance for which temporary minors should be
                      released
 
     """
     @type instance: string
     @param instance: the instance for which temporary minors should be
                      released
 
     """

+    assert isinstance(instance, basestring), \
+           "Invalid argument passed to ReleaseDRBDMinors"

     for key, name in self._temporary_drbds.items():
       if name == instance:
         del self._temporary_drbds[key]
 
     for key, name in self._temporary_drbds.items():
       if name == instance:
         del self._temporary_drbds[key]
 

+  @locking.ssynchronized(_config_lock)
+  def ReleaseDRBDMinors(self, instance):
+    """Release temporary drbd minors allocated for a given instance.
+
+    This should be called on the error paths, on the success paths
+    it's automatically called by the ConfigWriter add and update
+    functions.
+
+    This function is just a wrapper over L{_UnlockedReleaseDRBDMinors}.
+
+    @type instance: string
+    @param instance: the instance for which temporary minors should be
+                     released
+
+    """
+    self._UnlockedReleaseDRBDMinors(instance)
+
+  @locking.ssynchronized(_config_lock, shared=1)
+  def GetConfigVersion(self):
+    """Get the configuration version.
+
+    @return: Config version
+
+    """
+    return self._config_data.version
+
+  @locking.ssynchronized(_config_lock, shared=1)
+  def GetClusterName(self):
+    """Get cluster name.
+
+    @return: Cluster name
+
+    """
+    return self._config_data.cluster.cluster_name
+
+  @locking.ssynchronized(_config_lock, shared=1)
+  def GetMasterNode(self):
+    """Get the hostname of the master node for this cluster.
+
+    @return: Master hostname
+
+    """
+    return self._config_data.cluster.master_node
+
+  @locking.ssynchronized(_config_lock, shared=1)
+  def GetMasterIP(self):
+    """Get the IP of the master node for this cluster.
+
+    @return: Master IP
+
+    """
+    return self._config_data.cluster.master_ip
+
+  @locking.ssynchronized(_config_lock, shared=1)
+  def GetMasterNetdev(self):
+    """Get the master network device for this cluster.
+
+    """
+    return self._config_data.cluster.master_netdev
+
+  @locking.ssynchronized(_config_lock, shared=1)
+  def GetFileStorageDir(self):
+    """Get the file storage dir for this cluster.
+
+    """
+    return self._config_data.cluster.file_storage_dir
+
+  @locking.ssynchronized(_config_lock, shared=1)
+  def GetHypervisorType(self):
+    """Get the hypervisor type for this cluster.
+
+    """
+    return self._config_data.cluster.default_hypervisor
+

   @locking.ssynchronized(_config_lock, shared=1)
   def GetHostKey(self):
     """Return the rsa hostkey from the config.
 
   @locking.ssynchronized(_config_lock, shared=1)
   def GetHostKey(self):
     """Return the rsa hostkey from the config.
 

-    Args: None
+    @rtype: string
+    @return: the rsa hostkey

 
 

-    Returns: rsa hostkey

     """
     """

-    self._OpenConfig()

     return self._config_data.cluster.rsahostkeypub
 
   @locking.ssynchronized(_config_lock)
     return self._config_data.cluster.rsahostkeypub
 
   @locking.ssynchronized(_config_lock)

@@ -449,8 +710,9 @@ class ConfigWriter:
 
     This should be used after creating a new instance.
 
 
     This should be used after creating a new instance.
 

-    Args:
-      instance: the instance object
+    @type instance: L{objects.Instance}
+    @param instance: the instance object
+

     """
     if not isinstance(instance, objects.Instance):
       raise errors.ProgrammerError("Invalid type passed to AddInstance")
     """
     if not isinstance(instance, objects.Instance):
       raise errors.ProgrammerError("Invalid type passed to AddInstance")

@@ -459,28 +721,33 @@ class ConfigWriter:
       all_lvs = instance.MapLVsByNode()
       logging.info("Instance '%s' DISK_LAYOUT: %s", instance.name, all_lvs)
 
       all_lvs = instance.MapLVsByNode()
       logging.info("Instance '%s' DISK_LAYOUT: %s", instance.name, all_lvs)
 

-    self._OpenConfig()
+    all_macs = self._AllMACs()
+    for nic in instance.nics:
+      if nic.mac in all_macs:
+        raise errors.ConfigurationError("Cannot add instance %s:"
+          " MAC address '%s' already in use." % (instance.name, nic.mac))
+

     instance.serial_no = 1
     self._config_data.instances[instance.name] = instance
     self._config_data.cluster.serial_no += 1
     instance.serial_no = 1
     self._config_data.instances[instance.name] = instance
     self._config_data.cluster.serial_no += 1

+    self._UnlockedReleaseDRBDMinors(instance.name)
+    for nic in instance.nics:
+      self._temporary_macs.discard(nic.mac)

     self._WriteConfig()
 
   def _SetInstanceStatus(self, instance_name, status):
     """Set the instance's status to a given value.
 
     """
     self._WriteConfig()
 
   def _SetInstanceStatus(self, instance_name, status):
     """Set the instance's status to a given value.
 
     """

-    if status not in ("up", "down"):
-      raise errors.ProgrammerError("Invalid status '%s' passed to"
-                                   " ConfigWriter._SetInstanceStatus()" %
-                                   status)
-    self._OpenConfig()
+    assert isinstance(status, bool), \
+           "Invalid status '%s' passed to SetInstanceStatus" % (status,)

 
     if instance_name not in self._config_data.instances:
       raise errors.ConfigurationError("Unknown instance '%s'" %
                                       instance_name)
     instance = self._config_data.instances[instance_name]
 
     if instance_name not in self._config_data.instances:
       raise errors.ConfigurationError("Unknown instance '%s'" %
                                       instance_name)
     instance = self._config_data.instances[instance_name]

-    if instance.status != status:
-      instance.status = status
+    if instance.admin_up != status:
+      instance.admin_up = status

       instance.serial_no += 1
       self._WriteConfig()
 
       instance.serial_no += 1
       self._WriteConfig()
 

@@ -489,15 +756,13 @@ class ConfigWriter:
     """Mark the instance status to up in the config.
 
     """
     """Mark the instance status to up in the config.
 
     """

-    self._SetInstanceStatus(instance_name, "up")
+    self._SetInstanceStatus(instance_name, True)

 
   @locking.ssynchronized(_config_lock)
   def RemoveInstance(self, instance_name):
     """Remove the instance from the configuration.
 
     """
 
   @locking.ssynchronized(_config_lock)
   def RemoveInstance(self, instance_name):
     """Remove the instance from the configuration.
 
     """

-    self._OpenConfig()
-

     if instance_name not in self._config_data.instances:
       raise errors.ConfigurationError("Unknown instance '%s'" % instance_name)
     del self._config_data.instances[instance_name]
     if instance_name not in self._config_data.instances:
       raise errors.ConfigurationError("Unknown instance '%s'" % instance_name)
     del self._config_data.instances[instance_name]

@@ -513,7 +778,6 @@ class ConfigWriter:
     rename.
 
     """
     rename.
 
     """

-    self._OpenConfig()

     if old_name not in self._config_data.instances:
       raise errors.ConfigurationError("Unknown instance '%s'" % old_name)
     inst = self._config_data.instances[old_name]
     if old_name not in self._config_data.instances:
       raise errors.ConfigurationError("Unknown instance '%s'" % old_name)
     inst = self._config_data.instances[old_name]

@@ -530,7 +794,6 @@ class ConfigWriter:
                                                            disk.iv_name))
 
     self._config_data.instances[inst.name] = inst
                                                            disk.iv_name))
 
     self._config_data.instances[inst.name] = inst

-    self._config_data.cluster.serial_no += 1

     self._WriteConfig()
 
   @locking.ssynchronized(_config_lock)
     self._WriteConfig()
 
   @locking.ssynchronized(_config_lock)

@@ -538,7 +801,7 @@ class ConfigWriter:
     """Mark the status of an instance to down in the configuration.
 
     """
     """Mark the status of an instance to down in the configuration.
 
     """

-    self._SetInstanceStatus(instance_name, "down")
+    self._SetInstanceStatus(instance_name, False)

 
   def _UnlockedGetInstanceList(self):
     """Get the list of instances.
 
   def _UnlockedGetInstanceList(self):
     """Get the list of instances.

@@ -546,16 +809,14 @@ class ConfigWriter:
     This function is for internal use, when the config lock is already held.
 
     """
     This function is for internal use, when the config lock is already held.
 
     """

-    self._OpenConfig()

     return self._config_data.instances.keys()
 
   @locking.ssynchronized(_config_lock, shared=1)
   def GetInstanceList(self):
     """Get the list of instances.
 
     return self._config_data.instances.keys()
 
   @locking.ssynchronized(_config_lock, shared=1)
   def GetInstanceList(self):
     """Get the list of instances.
 

-    Returns:
-      array of instances, ex. ['instance2.example.com','instance1.example.com']
-      these contains all the instances, also the ones in Admin_down state
+    @return: array of instances, ex. ['instance2.example.com',
+        'instance1.example.com']

 
     """
     return self._UnlockedGetInstanceList()
 
     """
     return self._UnlockedGetInstanceList()

@@ -565,19 +826,15 @@ class ConfigWriter:
     """Attempt to expand an incomplete instance name.
 
     """
     """Attempt to expand an incomplete instance name.
 
     """

-    self._OpenConfig()
-

     return utils.MatchNameComponent(short_name,
                                     self._config_data.instances.keys())
 
   def _UnlockedGetInstanceInfo(self, instance_name):
     return utils.MatchNameComponent(short_name,
                                     self._config_data.instances.keys())
 
   def _UnlockedGetInstanceInfo(self, instance_name):

-    """Returns informations about an instance.
+    """Returns information about an instance.

 
     This function is for internal use, when the config lock is already held.
 
     """
 
     This function is for internal use, when the config lock is already held.
 
     """

-    self._OpenConfig()
-

     if instance_name not in self._config_data.instances:
       return None
 
     if instance_name not in self._config_data.instances:
       return None
 

@@ -585,16 +842,16 @@ class ConfigWriter:
 
   @locking.ssynchronized(_config_lock, shared=1)
   def GetInstanceInfo(self, instance_name):
 
   @locking.ssynchronized(_config_lock, shared=1)
   def GetInstanceInfo(self, instance_name):

-    """Returns informations about an instance.
+    """Returns information about an instance.

 
 

-    It takes the information from the configuration file. Other informations of
+    It takes the information from the configuration file. Other information of

     an instance are taken from the live systems.
 
     an instance are taken from the live systems.
 

-    Args:
-      instance: name of the instance, ex instance1.example.com
+    @param instance_name: name of the instance, e.g.
+        I{instance1.example.com}

 
 

-    Returns:
-      the instance object
+    @rtype: L{objects.Instance}
+    @return: the instance object

 
     """
     return self._UnlockedGetInstanceInfo(instance_name)
 
     """
     return self._UnlockedGetInstanceInfo(instance_name)

@@ -604,7 +861,7 @@ class ConfigWriter:
     """Get the configuration of all instances.
 
     @rtype: dict
     """Get the configuration of all instances.
 
     @rtype: dict

-    @returns: dict of (instance, instance_info), where instance_info is what
+    @return: dict of (instance, instance_info), where instance_info is what

               would GetInstanceInfo return for the node
 
     """
               would GetInstanceInfo return for the node
 
     """

@@ -616,13 +873,12 @@ class ConfigWriter:
   def AddNode(self, node):
     """Add a node to the configuration.
 
   def AddNode(self, node):
     """Add a node to the configuration.
 

-    Args:
-      node: an object.Node instance
+    @type node: L{objects.Node}
+    @param node: a Node instance

 
     """
     logging.info("Adding node %s to configuration" % node.name)
 
 
     """
     logging.info("Adding node %s to configuration" % node.name)
 

-    self._OpenConfig()

     node.serial_no = 1
     self._config_data.nodes[node.name] = node
     self._config_data.cluster.serial_no += 1
     node.serial_no = 1
     self._config_data.nodes[node.name] = node
     self._config_data.cluster.serial_no += 1

@@ -635,7 +891,6 @@ class ConfigWriter:
     """
     logging.info("Removing node %s from configuration" % node_name)
 
     """
     logging.info("Removing node %s from configuration" % node_name)
 

-    self._OpenConfig()

     if node_name not in self._config_data.nodes:
       raise errors.ConfigurationError("Unknown node '%s'" % node_name)
 
     if node_name not in self._config_data.nodes:
       raise errors.ConfigurationError("Unknown node '%s'" % node_name)
 

@@ -648,23 +903,21 @@ class ConfigWriter:
     """Attempt to expand an incomplete instance name.
 
     """
     """Attempt to expand an incomplete instance name.
 
     """

-    self._OpenConfig()
-

     return utils.MatchNameComponent(short_name,
                                     self._config_data.nodes.keys())
 
   def _UnlockedGetNodeInfo(self, node_name):
     """Get the configuration of a node, as stored in the config.
 
     return utils.MatchNameComponent(short_name,
                                     self._config_data.nodes.keys())
 
   def _UnlockedGetNodeInfo(self, node_name):
     """Get the configuration of a node, as stored in the config.
 

-    This function is for internal use, when the config lock is already held.
+    This function is for internal use, when the config lock is already
+    held.

 
 

-    Args: node: nodename (tuple) of the node
+    @param node_name: the node name, e.g. I{node1.example.com}

 
 

-    Returns: the node object
+    @rtype: L{objects.Node}
+    @return: the node object

 
     """
 
     """

-    self._OpenConfig()
-

     if node_name not in self._config_data.nodes:
       return None
 
     if node_name not in self._config_data.nodes:
       return None
 

@@ -675,9 +928,12 @@ class ConfigWriter:
   def GetNodeInfo(self, node_name):
     """Get the configuration of a node, as stored in the config.
 
   def GetNodeInfo(self, node_name):
     """Get the configuration of a node, as stored in the config.
 

-    Args: node: nodename (tuple) of the node
+    This is just a locked wrapper over L{_UnlockedGetNodeInfo}.

 
 

-    Returns: the node object
+    @param node_name: the node name, e.g. I{node1.example.com}
+
+    @rtype: L{objects.Node}
+    @return: the node object

 
     """
     return self._UnlockedGetNodeInfo(node_name)
 
     """
     return self._UnlockedGetNodeInfo(node_name)

@@ -685,10 +941,12 @@ class ConfigWriter:
   def _UnlockedGetNodeList(self):
     """Return the list of nodes which are in the configuration.
 
   def _UnlockedGetNodeList(self):
     """Return the list of nodes which are in the configuration.
 

-    This function is for internal use, when the config lock is already held.
+    This function is for internal use, when the config lock is already
+    held.
+
+    @rtype: list

 
     """
 
     """

-    self._OpenConfig()

     return self._config_data.nodes.keys()
 
 
     return self._config_data.nodes.keys()
 
 

@@ -700,11 +958,20 @@ class ConfigWriter:
     return self._UnlockedGetNodeList()
 
   @locking.ssynchronized(_config_lock, shared=1)
     return self._UnlockedGetNodeList()
 
   @locking.ssynchronized(_config_lock, shared=1)

+  def GetOnlineNodeList(self):
+    """Return the list of nodes which are online.
+
+    """
+    all_nodes = [self._UnlockedGetNodeInfo(node)
+                 for node in self._UnlockedGetNodeList()]
+    return [node.name for node in all_nodes if not node.offline]
+
+  @locking.ssynchronized(_config_lock, shared=1)

   def GetAllNodesInfo(self):
     """Get the configuration of all nodes.
 
     @rtype: dict
   def GetAllNodesInfo(self):
     """Get the configuration of all nodes.
 
     @rtype: dict

-    @returns: dict of (node, node_info), where node_info is what
+    @return: dict of (node, node_info), where node_info is what

               would GetNodeInfo return for the node
 
     """
               would GetNodeInfo return for the node
 
     """

@@ -712,12 +979,72 @@ class ConfigWriter:
                     for node in self._UnlockedGetNodeList()])
     return my_dict
 
                     for node in self._UnlockedGetNodeList()])
     return my_dict
 

+  def _UnlockedGetMasterCandidateStats(self, exceptions=None):
+    """Get the number of current and maximum desired and possible candidates.
+
+    @type exceptions: list
+    @param exceptions: if passed, list of nodes that should be ignored
+    @rtype: tuple
+    @return: tuple of (current, desired and possible)
+
+    """
+    mc_now = mc_max = 0
+    for node in self._config_data.nodes.values():
+      if exceptions and node.name in exceptions:
+        continue
+      if not (node.offline or node.drained):
+        mc_max += 1
+      if node.master_candidate:
+        mc_now += 1
+    mc_max = min(mc_max, self._config_data.cluster.candidate_pool_size)
+    return (mc_now, mc_max)
+

   @locking.ssynchronized(_config_lock, shared=1)
   @locking.ssynchronized(_config_lock, shared=1)

-  def DumpConfig(self):
-    """Return the entire configuration of the cluster.
+  def GetMasterCandidateStats(self, exceptions=None):
+    """Get the number of current and maximum possible candidates.
+
+    This is just a wrapper over L{_UnlockedGetMasterCandidateStats}.
+
+    @type exceptions: list
+    @param exceptions: if passed, list of nodes that should be ignored
+    @rtype: tuple
+    @return: tuple of (current, max)
+

     """
     """

-    self._OpenConfig()
-    return self._config_data
+    return self._UnlockedGetMasterCandidateStats(exceptions)
+
+  @locking.ssynchronized(_config_lock)
+  def MaintainCandidatePool(self):
+    """Try to grow the candidate pool to the desired size.
+
+    @rtype: list
+    @return: list with the adjusted nodes (L{objects.Node} instances)
+
+    """
+    mc_now, mc_max = self._UnlockedGetMasterCandidateStats()
+    mod_list = []
+    if mc_now < mc_max:
+      node_list = self._config_data.nodes.keys()
+      random.shuffle(node_list)
+      for name in node_list:
+        if mc_now >= mc_max:
+          break
+        node = self._config_data.nodes[name]
+        if node.master_candidate or node.offline or node.drained:
+          continue
+        mod_list.append(node)
+        node.master_candidate = True
+        node.serial_no += 1
+        mc_now += 1
+      if mc_now != mc_max:
+        # this should not happen
+        logging.warning("Warning: MaintainCandidatePool didn't manage to"
+                        " fill the candidate pool (%d/%d)", mc_now, mc_max)
+      if mod_list:
+        self._config_data.cluster.serial_no += 1
+        self._WriteConfig()
+
+    return mod_list

 
   def _BumpSerialNo(self):
     """Bump up the serial number of the config.
 
   def _BumpSerialNo(self):
     """Bump up the serial number of the config.

@@ -728,26 +1055,7 @@ class ConfigWriter:
   def _OpenConfig(self):
     """Read the config data from disk.
 
   def _OpenConfig(self):
     """Read the config data from disk.
 

-    In case we already have configuration data and the config file has
-    the same mtime as when we read it, we skip the parsing of the
-    file, since de-serialisation could be slow.
-

     """
     """

-    try:
-      st = os.stat(self._cfg_file)
-    except OSError, err:
-      raise errors.ConfigurationError("Can't stat config file: %s" % err)
-    if (self._config_data is not None and
-        self._config_time is not None and
-        self._config_time == st.st_mtime and
-        self._config_size == st.st_size and
-        self._config_inode == st.st_ino):
-      # data is current, so skip loading of config file
-      return
-
-    # Make sure the configuration has the right version
-    ValidateConfig()
-

     f = open(self._cfg_file, 'r')
     try:
       try:
     f = open(self._cfg_file, 'r')
     try:
       try:

@@ -756,14 +1064,22 @@ class ConfigWriter:
         raise errors.ConfigurationError(err)
     finally:
       f.close()
         raise errors.ConfigurationError(err)
     finally:
       f.close()

+
+    # Make sure the configuration has the right version
+    _ValidateConfig(data)
+

     if (not hasattr(data, 'cluster') or
         not hasattr(data.cluster, 'rsahostkeypub')):
       raise errors.ConfigurationError("Incomplete configuration"
                                       " (missing cluster.rsahostkeypub)")
     if (not hasattr(data, 'cluster') or
         not hasattr(data.cluster, 'rsahostkeypub')):
       raise errors.ConfigurationError("Incomplete configuration"
                                       " (missing cluster.rsahostkeypub)")

+
+    # Upgrade configuration if needed
+    data.UpgradeConfig()
+

     self._config_data = data
     self._config_data = data

-    self._config_time = st.st_mtime
-    self._config_size = st.st_size
-    self._config_inode = st.st_ino
+    # reset the last serial as -1 so that the next write will cause
+    # ssconf update
+    self._last_cluster_serial = -1

 
   def _DistributeConfig(self):
     """Distribute the configuration to the other nodes.
 
   def _DistributeConfig(self):
     """Distribute the configuration to the other nodes.

@@ -775,16 +1091,26 @@ class ConfigWriter:
     if self._offline:
       return True
     bad = False
     if self._offline:
       return True
     bad = False

-    nodelist = self._UnlockedGetNodeList()
-    myhostname = self._my_hostname

 
 

-    try:
-      nodelist.remove(myhostname)
-    except ValueError:
-      pass
+    node_list = []
+    addr_list = []
+    myhostname = self._my_hostname
+    # we can skip checking whether _UnlockedGetNodeInfo returns None
+    # since the node list comes from _UnlocketGetNodeList, and we are
+    # called with the lock held, so no modifications should take place
+    # in between
+    for node_name in self._UnlockedGetNodeList():
+      if node_name == myhostname:
+        continue
+      node_info = self._UnlockedGetNodeInfo(node_name)
+      if not node_info.master_candidate:
+        continue
+      node_list.append(node_info.name)
+      addr_list.append(node_info.primary_ip)

 
 

-    result = rpc.call_upload_file(nodelist, self._cfg_file)
-    for node in nodelist:
+    result = rpc.RpcRunner.call_upload_file(node_list, self._cfg_file,
+                                            address_list=addr_list)
+    for node in node_list:

       if not result[node]:
         logging.error("copy of file %s to node %s failed",
                       self._cfg_file, node)
       if not result[node]:
         logging.error("copy of file %s to node %s failed",
                       self._cfg_file, node)

@@ -795,6 +1121,15 @@ class ConfigWriter:
     """Write the configuration data to persistent storage.
 
     """
     """Write the configuration data to persistent storage.
 
     """

+    # first, cleanup the _temporary_ids set, if an ID is now in the
+    # other objects it should be discarded to prevent unbounded growth
+    # of that structure
+    self._CleanupTemporaryIDs()
+    config_errors = self._UnlockedVerifyConfig()
+    if config_errors:
+      raise errors.ConfigurationError("Configuration data is not"
+                                      " consistent: %s" %
+                                      (", ".join(config_errors)))

     if destination is None:
       destination = self._cfg_file
     self._BumpSerialNo()
     if destination is None:
       destination = self._cfg_file
     self._BumpSerialNo()

@@ -810,57 +1145,58 @@ class ConfigWriter:
     # we don't need to do os.close(fd) as f.close() did it
     os.rename(name, destination)
     self.write_count += 1
     # we don't need to do os.close(fd) as f.close() did it
     os.rename(name, destination)
     self.write_count += 1

-    # re-set our cache as not to re-read the config file
-    try:
-      st = os.stat(destination)
-    except OSError, err:
-      raise errors.ConfigurationError("Can't stat config file: %s" % err)
-    self._config_time = st.st_mtime
-    self._config_size = st.st_size
-    self._config_inode = st.st_ino
-    # and redistribute the config file
+
+    # and redistribute the config file to master candidates

     self._DistributeConfig()
 
     self._DistributeConfig()
 

-  @locking.ssynchronized(_config_lock)
-  def InitConfig(self, node, primary_ip, secondary_ip,
-                 hostkeypub, mac_prefix, vg_name, def_bridge):
-    """Create the initial cluster configuration.
-
-    It will contain the current node, which will also be the master
-    node, and no instances or operating systmes.
-
-    Args:
-      node: the nodename of the initial node
-      primary_ip: the IP address of the current host
-      secondary_ip: the secondary IP of the current host or None
-      hostkeypub: the public hostkey of this host
-
-    """
-    hu_port = constants.FIRST_DRBD_PORT - 1
-    globalconfig = objects.Cluster(serial_no=1,
-                                   rsahostkeypub=hostkeypub,
-                                   highest_used_port=hu_port,
-                                   mac_prefix=mac_prefix,
-                                   volume_group_name=vg_name,
-                                   default_bridge=def_bridge,
-                                   tcpudp_port_pool=set())
-    if secondary_ip is None:
-      secondary_ip = primary_ip
-    nodeconfig = objects.Node(name=node, primary_ip=primary_ip,
-                              secondary_ip=secondary_ip, serial_no=1)
-
-    self._config_data = objects.ConfigData(nodes={node: nodeconfig},
-                                           instances={},
-                                           cluster=globalconfig,
-                                           serial_no=1)
-    self._WriteConfig()
+    # Write ssconf files on all nodes (including locally)
+    if self._last_cluster_serial < self._config_data.cluster.serial_no:
+      if not self._offline:
+        rpc.RpcRunner.call_write_ssconf_files(self._UnlockedGetNodeList(),
+                                              self._UnlockedGetSsconfValues())
+      self._last_cluster_serial = self._config_data.cluster.serial_no
+
+  def _UnlockedGetSsconfValues(self):
+    """Return the values needed by ssconf.
+
+    @rtype: dict
+    @return: a dictionary with keys the ssconf names and values their
+        associated value
+
+    """
+    fn = "\n".join
+    instance_names = utils.NiceSort(self._UnlockedGetInstanceList())
+    node_names = utils.NiceSort(self._UnlockedGetNodeList())
+    node_info = [self._UnlockedGetNodeInfo(name) for name in node_names]
+
+    instance_data = fn(instance_names)
+    off_data = fn(node.name for node in node_info if node.offline)
+    on_data = fn(node.name for node in node_info if not node.offline)
+    mc_data = fn(node.name for node in node_info if node.master_candidate)
+    node_data = fn(node_names)
+
+    cluster = self._config_data.cluster
+    cluster_tags = fn(cluster.GetTags())
+    return {
+      constants.SS_CLUSTER_NAME: cluster.cluster_name,
+      constants.SS_CLUSTER_TAGS: cluster_tags,
+      constants.SS_FILE_STORAGE_DIR: cluster.file_storage_dir,
+      constants.SS_MASTER_CANDIDATES: mc_data,
+      constants.SS_MASTER_IP: cluster.master_ip,
+      constants.SS_MASTER_NETDEV: cluster.master_netdev,
+      constants.SS_MASTER_NODE: cluster.master_node,
+      constants.SS_NODE_LIST: node_data,
+      constants.SS_OFFLINE_NODES: off_data,
+      constants.SS_ONLINE_NODES: on_data,
+      constants.SS_INSTANCE_LIST: instance_data,
+      constants.SS_RELEASE_VERSION: constants.RELEASE_VERSION,
+      }

 
   @locking.ssynchronized(_config_lock, shared=1)
   def GetVGName(self):
     """Return the volume group name.
 
     """
 
   @locking.ssynchronized(_config_lock, shared=1)
   def GetVGName(self):
     """Return the volume group name.
 
     """

-    self._OpenConfig()

     return self._config_data.cluster.volume_group_name
 
   @locking.ssynchronized(_config_lock)
     return self._config_data.cluster.volume_group_name
 
   @locking.ssynchronized(_config_lock)

@@ -868,7 +1204,6 @@ class ConfigWriter:
     """Set the volume group name.
 
     """
     """Set the volume group name.
 
     """

-    self._OpenConfig()

     self._config_data.cluster.volume_group_name = vg_name
     self._config_data.cluster.serial_no += 1
     self._WriteConfig()
     self._config_data.cluster.volume_group_name = vg_name
     self._config_data.cluster.serial_no += 1
     self._WriteConfig()

@@ -878,7 +1213,6 @@ class ConfigWriter:
     """Return the default bridge.
 
     """
     """Return the default bridge.
 
     """

-    self._OpenConfig()

     return self._config_data.cluster.default_bridge
 
   @locking.ssynchronized(_config_lock, shared=1)
     return self._config_data.cluster.default_bridge
 
   @locking.ssynchronized(_config_lock, shared=1)

@@ -886,19 +1220,16 @@ class ConfigWriter:
     """Return the mac prefix.
 
     """
     """Return the mac prefix.
 
     """

-    self._OpenConfig()

     return self._config_data.cluster.mac_prefix
 
   @locking.ssynchronized(_config_lock, shared=1)
   def GetClusterInfo(self):
     return self._config_data.cluster.mac_prefix
 
   @locking.ssynchronized(_config_lock, shared=1)
   def GetClusterInfo(self):

-    """Returns informations about the cluster
+    """Returns information about the cluster

 
 

-    Returns:
-      the cluster object
+    @rtype: L{objects.Cluster}
+    @return: the cluster object

 
     """
 
     """

-    self._OpenConfig()
-

     return self._config_data.cluster
 
   @locking.ssynchronized(_config_lock)
     return self._config_data.cluster
 
   @locking.ssynchronized(_config_lock)

@@ -911,14 +1242,20 @@ class ConfigWriter:
     that all modified objects will be saved, but the target argument
     is the one the caller wants to ensure that it's saved.
 
     that all modified objects will be saved, but the target argument
     is the one the caller wants to ensure that it's saved.
 

+    @param target: an instance of either L{objects.Cluster},
+        L{objects.Node} or L{objects.Instance} which is existing in
+        the cluster
+

     """
     if self._config_data is None:
       raise errors.ProgrammerError("Configuration file not read,"
                                    " cannot save.")
     """
     if self._config_data is None:
       raise errors.ProgrammerError("Configuration file not read,"
                                    " cannot save.")

+    update_serial = False

     if isinstance(target, objects.Cluster):
       test = target == self._config_data.cluster
     elif isinstance(target, objects.Node):
       test = target in self._config_data.nodes.values()
     if isinstance(target, objects.Cluster):
       test = target == self._config_data.cluster
     elif isinstance(target, objects.Node):
       test = target in self._config_data.nodes.values()

+      update_serial = True

     elif isinstance(target, objects.Instance):
       test = target in self._config_data.instances.values()
     else:
     elif isinstance(target, objects.Instance):
       test = target in self._config_data.instances.values()
     else:

@@ -929,4 +1266,13 @@ class ConfigWriter:
                                       " has been read or unknown object")
     target.serial_no += 1
 
                                       " has been read or unknown object")
     target.serial_no += 1
 

+    if update_serial:
+      # for node updates, we need to increase the cluster serial too
+      self._config_data.cluster.serial_no += 1
+
+    if isinstance(target, objects.Instance):
+      self._UnlockedReleaseDRBDMinors(target.name)
+      for nic in target.nics:
+        self._temporary_macs.discard(nic.mac)
+

     self._WriteConfig()
     self._WriteConfig()