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22 """Block device abstraction - base class and utility functions"""
26 from ganeti import objects
27 from ganeti import constants
28 from ganeti import utils
29 from ganeti import errors
32 class BlockDev(object):
33 """Block device abstract class.
35 A block device can be in the following states:
36 - not existing on the system, and by `Create()` it goes into:
37 - existing but not setup/not active, and by `Assemble()` goes into:
38 - active read-write and by `Open()` it goes into
39 - online (=used, or ready for use)
41 A device can also be online but read-only, however we are not using
42 the readonly state (LV has it, if needed in the future) and we are
43 usually looking at this like at a stack, so it's easier to
44 conceptualise the transition from not-existing to online and back
47 The many different states of the device are due to the fact that we
48 need to cover many device types:
49 - logical volumes are created, lvchange -a y $lv, and used
50 - drbd devices are attached to a local disk/remote peer and made primary
52 A block device is identified by three items:
53 - the /dev path of the device (dynamic)
54 - a unique ID of the device (static)
55 - it's major/minor pair (dynamic)
57 Not all devices implement both the first two as distinct items. LVM
58 logical volumes have their unique ID (the pair volume group, logical
59 volume name) in a 1-to-1 relation to the dev path. For DRBD devices,
60 the /dev path is again dynamic and the unique id is the pair (host1,
63 You can get to a device in two ways:
64 - creating the (real) device, which returns you
65 an attached instance (lvcreate)
66 - attaching of a python instance to an existing (real) device
68 The second point, the attachment to a device, is different
69 depending on whether the device is assembled or not. At init() time,
70 we search for a device with the same unique_id as us. If found,
71 good. It also means that the device is already assembled. If not,
72 after assembly we'll have our correct major/minor.
75 def __init__(self, unique_id, children, size, params):
76 self._children = children
78 self.unique_id = unique_id
86 """Assemble the device from its components.
88 Implementations of this method by child classes must ensure that:
89 - after the device has been assembled, it knows its major/minor
90 numbers; this allows other devices (usually parents) to probe
91 correctly for their children
92 - calling this method on an existing, in-use device is safe
93 - if the device is already configured (and in an OK state),
94 this method is idempotent
100 """Find a device which matches our config and attach to it.
103 raise NotImplementedError
106 """Notifies that the device will no longer be used for I/O.
109 raise NotImplementedError
112 def Create(cls, unique_id, children, size, spindles, params, excl_stor):
113 """Create the device.
115 If the device cannot be created, it will return None
116 instead. Error messages go to the logging system.
118 Note that for some devices, the unique_id is used, and for other,
119 the children. The idea is that these two, taken together, are
120 enough for both creation and assembly (later).
122 @type unique_id: 2-element tuple or list
123 @param unique_id: unique identifier; the details depend on the actual device
125 @type children: list of L{BlockDev}
126 @param children: for hierarchical devices, the child devices
128 @param size: size in MiB
130 @param spindles: number of physical disk to dedicate to the device
132 @param params: device-specific options/parameters
133 @type excl_stor: bool
134 @param excl_stor: whether exclusive_storage is active
136 @return: the created device, or C{None} in case of an error
139 raise NotImplementedError
142 """Remove this device.
144 This makes sense only for some of the device types: LV and file
145 storage. Also note that if the device can't attach, the removal
149 raise NotImplementedError
151 def Rename(self, new_id):
152 """Rename this device.
154 This may or may not make sense for a given device type.
157 raise NotImplementedError
159 def Open(self, force=False):
160 """Make the device ready for use.
162 This makes the device ready for I/O. For now, just the DRBD
165 The force parameter signifies that if the device has any kind of
166 --force thing, it should be used, we know what we are doing.
171 raise NotImplementedError
174 """Shut down the device, freeing its children.
176 This undoes the `Assemble()` work, except for the child
177 assembling; as such, the children on the device are still
178 assembled after this call.
181 raise NotImplementedError
183 def SetSyncParams(self, params):
184 """Adjust the synchronization parameters of the mirror.
186 In case this is not a mirroring device, this is no-op.
188 @param params: dictionary of LD level disk parameters related to the
191 @return: a list of error messages, emitted both by the current node and by
192 children. An empty list means no errors.
197 for child in self._children:
198 result.extend(child.SetSyncParams(params))
201 def PauseResumeSync(self, pause):
202 """Pause/Resume the sync of the mirror.
204 In case this is not a mirroring device, this is no-op.
207 @param pause: Whether to pause or resume
212 for child in self._children:
213 result = result and child.PauseResumeSync(pause)
216 def GetSyncStatus(self):
217 """Returns the sync status of the device.
219 If this device is a mirroring device, this function returns the
220 status of the mirror.
222 If sync_percent is None, it means the device is not syncing.
224 If estimated_time is None, it means we can't estimate
225 the time needed, otherwise it's the time left in seconds.
227 If is_degraded is True, it means the device is missing
228 redundancy. This is usually a sign that something went wrong in
229 the device setup, if sync_percent is None.
231 The ldisk parameter represents the degradation of the local
232 data. This is only valid for some devices, the rest will always
233 return False (not degraded).
235 @rtype: objects.BlockDevStatus
238 return objects.BlockDevStatus(dev_path=self.dev_path,
244 ldisk_status=constants.LDS_OKAY)
246 def CombinedSyncStatus(self):
247 """Calculate the mirror status recursively for our children.
249 The return value is the same as for `GetSyncStatus()` except the
250 minimum percent and maximum time are calculated across our
253 @rtype: objects.BlockDevStatus
256 status = self.GetSyncStatus()
258 min_percent = status.sync_percent
259 max_time = status.estimated_time
260 is_degraded = status.is_degraded
261 ldisk_status = status.ldisk_status
264 for child in self._children:
265 child_status = child.GetSyncStatus()
267 if min_percent is None:
268 min_percent = child_status.sync_percent
269 elif child_status.sync_percent is not None:
270 min_percent = min(min_percent, child_status.sync_percent)
273 max_time = child_status.estimated_time
274 elif child_status.estimated_time is not None:
275 max_time = max(max_time, child_status.estimated_time)
277 is_degraded = is_degraded or child_status.is_degraded
279 if ldisk_status is None:
280 ldisk_status = child_status.ldisk_status
281 elif child_status.ldisk_status is not None:
282 ldisk_status = max(ldisk_status, child_status.ldisk_status)
284 return objects.BlockDevStatus(dev_path=self.dev_path,
287 sync_percent=min_percent,
288 estimated_time=max_time,
289 is_degraded=is_degraded,
290 ldisk_status=ldisk_status)
292 def SetInfo(self, text):
293 """Update metadata with info text.
295 Only supported for some device types.
298 for child in self._children:
301 def Grow(self, amount, dryrun, backingstore):
302 """Grow the block device.
304 @type amount: integer
305 @param amount: the amount (in mebibytes) to grow with
306 @type dryrun: boolean
307 @param dryrun: whether to execute the operation in simulation mode
308 only, without actually increasing the size
309 @param backingstore: whether to execute the operation on backing storage
310 only, or on "logical" storage only; e.g. DRBD is logical storage,
311 whereas LVM, file, RBD are backing storage
314 raise NotImplementedError
316 def GetActualSize(self):
317 """Return the actual disk size.
319 @note: the device needs to be active when this is called
322 assert self.attached, "BlockDevice not attached in GetActualSize()"
323 result = utils.RunCmd(["blockdev", "--getsize64", self.dev_path])
325 ThrowError("blockdev failed (%s): %s",
326 result.fail_reason, result.output)
328 sz = int(result.output.strip())
329 except (ValueError, TypeError), err:
330 ThrowError("Failed to parse blockdev output: %s", str(err))
333 def GetActualSpindles(self):
334 """Return the actual number of spindles used.
336 This is not supported by all devices; if not supported, C{None} is returned.
338 @note: the device needs to be active when this is called
341 assert self.attached, "BlockDevice not attached in GetActualSpindles()"
344 def GetActualDimensions(self):
345 """Return the actual disk size and number of spindles used.
348 @return: (size, spindles); spindles is C{None} when they are not supported
350 @note: the device needs to be active when this is called
353 return (self.GetActualSize(), self.GetActualSpindles())
356 return ("<%s: unique_id: %s, children: %s, %s:%s, %s>" %
357 (self.__class__, self.unique_id, self._children,
358 self.major, self.minor, self.dev_path))
361 def ThrowError(msg, *args):
362 """Log an error to the node daemon and the raise an exception.
365 @param msg: the text of the exception
366 @raise errors.BlockDeviceError
372 raise errors.BlockDeviceError(msg)
375 def IgnoreError(fn, *args, **kwargs):
376 """Executes the given function, ignoring BlockDeviceErrors.
378 This is used in order to simplify the execution of cleanup or
382 @return: True when fn didn't raise an exception, False otherwise
388 except errors.BlockDeviceError, err:
389 logging.warning("Caught BlockDeviceError but ignoring: %s", str(err))