ganeti.storage.base

33 """Block device abstract class. 34 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) 40 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 45 like a linear one. 46 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 51 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) 56 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, 61 dev1), (host2, dev2). 62 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 67 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. 73 74 """

75 - def __init__(self, unique_id, children, size, params):

76 self._children = children 77 self.dev_path = None 78 self.unique_id = unique_id 79 self.major = None 80 self.minor = None 81 self.attached = False 82 self.size = size 83 self.params = params

84

85 - def Assemble(self):

86 """Assemble the device from its components. 87 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 95 96 """ 97 pass

98

99 - def Attach(self):

100 """Find a device which matches our config and attach to it. 101 102 """ 103 raise NotImplementedError

104

105 - def Close(self):

106 """Notifies that the device will no longer be used for I/O. 107 108 """ 109 raise NotImplementedError

110 111 @classmethod

112 - def Create(cls, unique_id, children, size, spindles, params, excl_stor):

113 """Create the device. 114 115 If the device cannot be created, it will return None 116 instead. Error messages go to the logging system. 117 118 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). 121 122 @type unique_id: 2-element tuple or list 123 @param unique_id: unique identifier; the details depend on the actual device 124 type 125 @type children: list of L{BlockDev} 126 @param children: for hierarchical devices, the child devices 127 @type size: float 128 @param size: size in MiB 129 @type spindles: int 130 @param spindles: number of physical disk to dedicate to the device 131 @type params: dict 132 @param params: device-specific options/parameters 133 @type excl_stor: bool 134 @param excl_stor: whether exclusive_storage is active 135 @rtype: L{BlockDev} 136 @return: the created device, or C{None} in case of an error 137 138 """ 139 raise NotImplementedError

140

141 - def Remove(self):

142 """Remove this device. 143 144 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 146 can't be completed. 147 148 """ 149 raise NotImplementedError

150

151 - def Rename(self, new_id):

152 """Rename this device. 153 154 This may or may not make sense for a given device type. 155 156 """ 157 raise NotImplementedError

158

159 - def Open(self, force=False):

160 """Make the device ready for use. 161 162 This makes the device ready for I/O. For now, just the DRBD 163 devices need this. 164 165 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. 167 168 @type force: boolean 169 170 """ 171 raise NotImplementedError

172

173 - def Shutdown(self):

174 """Shut down the device, freeing its children. 175 176 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. 179 180 """ 181 raise NotImplementedError

182

183 - def SetSyncParams(self, params):

184 """Adjust the synchronization parameters of the mirror. 185 186 In case this is not a mirroring device, this is no-op. 187 188 @param params: dictionary of LD level disk parameters related to the 189 synchronization. 190 @rtype: list 191 @return: a list of error messages, emitted both by the current node and by 192 children. An empty list means no errors. 193 194 """ 195 result = [] 196 if self._children: 197 for child in self._children: 198 result.extend(child.SetSyncParams(params)) 199 return result

200

201 - def PauseResumeSync(self, pause):

202 """Pause/Resume the sync of the mirror. 203 204 In case this is not a mirroring device, this is no-op. 205 206 @type pause: boolean 207 @param pause: Whether to pause or resume 208 209 """ 210 result = True 211 if self._children: 212 for child in self._children: 213 result = result and child.PauseResumeSync(pause) 214 return result

215

216 - def GetSyncStatus(self):

217 """Returns the sync status of the device. 218 219 If this device is a mirroring device, this function returns the 220 status of the mirror. 221 222 If sync_percent is None, it means the device is not syncing. 223 224 If estimated_time is None, it means we can't estimate 225 the time needed, otherwise it's the time left in seconds. 226 227 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. 230 231 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). 234 235 @rtype: objects.BlockDevStatus 236 237 """ 238 return objects.BlockDevStatus(dev_path=self.dev_path, 239 major=self.major, 240 minor=self.minor, 241 sync_percent=None, 242 estimated_time=None, 243 is_degraded=False, 244 ldisk_status=constants.LDS_OKAY)

245

246 - def CombinedSyncStatus(self):

247 """Calculate the mirror status recursively for our children. 248 249 The return value is the same as for `GetSyncStatus()` except the 250 minimum percent and maximum time are calculated across our 251 children. 252 253 @rtype: objects.BlockDevStatus 254 255 """ 256 status = self.GetSyncStatus() 257 258 min_percent = status.sync_percent 259 max_time = status.estimated_time 260 is_degraded = status.is_degraded 261 ldisk_status = status.ldisk_status 262 263 if self._children: 264 for child in self._children: 265 child_status = child.GetSyncStatus() 266 267 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) 271 272 if max_time is None: 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) 276 277 is_degraded = is_degraded or child_status.is_degraded 278 279 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) 283 284 return objects.BlockDevStatus(dev_path=self.dev_path, 285 major=self.major, 286 minor=self.minor, 287 sync_percent=min_percent, 288 estimated_time=max_time, 289 is_degraded=is_degraded, 290 ldisk_status=ldisk_status)

291

292 - def SetInfo(self, text):

293 """Update metadata with info text. 294 295 Only supported for some device types. 296 297 """ 298 for child in self._children: 299 child.SetInfo(text)

300

301 - def Grow(self, amount, dryrun, backingstore, excl_stor):

302 """Grow the block device. 303 304 @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 312 @type excl_stor: boolean 313 @param excl_stor: Whether exclusive_storage is active 314 315 """ 316 raise NotImplementedError

317

318 - def GetActualSize(self):

319 """Return the actual disk size. 320 321 @note: the device needs to be active when this is called 322 323 """ 324 assert self.attached, "BlockDevice not attached in GetActualSize()" 325 result = utils.RunCmd(["blockdev", "--getsize64", self.dev_path]) 326 if result.failed: 327 ThrowError("blockdev failed (%s): %s", 328 result.fail_reason, result.output) 329 try: 330 sz = int(result.output.strip()) 331 except (ValueError, TypeError), err: 332 ThrowError("Failed to parse blockdev output: %s", str(err)) 333 return sz

334

335 - def GetActualSpindles(self):

336 """Return the actual number of spindles used. 337 338 This is not supported by all devices; if not supported, C{None} is returned. 339 340 @note: the device needs to be active when this is called 341 342 """ 343 assert self.attached, "BlockDevice not attached in GetActualSpindles()" 344 return None

345

346 - def GetActualDimensions(self):

347 """Return the actual disk size and number of spindles used. 348 349 @rtype: tuple 350 @return: (size, spindles); spindles is C{None} when they are not supported 351 352 @note: the device needs to be active when this is called 353 354 """ 355 return (self.GetActualSize(), self.GetActualSpindles())

356

357 - def __repr__(self):

358 return ("<%s: unique_id: %s, children: %s, %s:%s, %s>" % 359 (self.__class__, self.unique_id, self._children, 360 self.major, self.minor, self.dev_path))

Source Code for Module ganeti.storage.base