Package ganeti :: Package storage :: Module base :: Class BlockDev
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Class BlockDev

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Block device abstract class.

A block device can be in the following states:

A device can also be online but read-only, however we are not using the readonly state (LV has it, if needed in the future) and we are usually looking at this like at a stack, so it's easier to conceptualise the transition from not-existing to online and back like a linear one.

The many different states of the device are due to the fact that we need to cover many device types:

A block device is identified by three items:

Not all devices implement both the first two as distinct items. LVM logical volumes have their unique ID (the pair volume group, logical volume name) in a 1-to-1 relation to the dev path. For DRBD devices, the /dev path is again dynamic and the unique id is the pair (host1, dev1), (host2, dev2).

You can get to a device in two ways:

The second point, the attachment to a device, is different depending on whether the device is assembled or not. At init() time, we search for a device with the same unique_id as us. If found, good. It also means that the device is already assembled. If not, after assembly we'll have our correct major/minor.

Instance Methods [hide private]
 
__init__(self, unique_id, children, size, params, dyn_params, *args)
x.__init__(...) initializes x; see help(type(x)) for signature
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Assemble(self)
Assemble the device from its components.
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Attach(self)
Find a device which matches our config and attach to it.
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Close(self)
Notifies that the device will no longer be used for I/O.
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Remove(self)
Remove this device.
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Rename(self, new_id)
Rename this device.
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Open(self, force=False)
Make the device ready for use.
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Shutdown(self)
Shut down the device, freeing its children.
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list
SetSyncParams(self, params)
Adjust the synchronization parameters of the mirror.
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PauseResumeSync(self, pause)
Pause/Resume the sync of the mirror.
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objects.BlockDevStatus
GetSyncStatus(self)
Returns the sync status of the device.
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objects.BlockDevStatus
CombinedSyncStatus(self)
Calculate the mirror status recursively for our children.
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SetInfo(self, text)
Update metadata with info text.
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Grow(self, amount, dryrun, backingstore, excl_stor)
Grow the block device.
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GetActualSize(self)
Return the actual disk size.
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GetActualSpindles(self)
Return the actual number of spindles used.
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tuple
GetActualDimensions(self)
Return the actual disk size and number of spindles used.
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string
GetUserspaceAccessUri(self, hypervisor)
Return URIs hypervisors can use to access disks in userspace mode.
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__repr__(self)
repr(x)
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Inherited from object: __delattr__, __format__, __getattribute__, __hash__, __new__, __reduce__, __reduce_ex__, __setattr__, __sizeof__, __str__, __subclasshook__

Class Methods [hide private]
BlockDev
Create(cls, unique_id, children, size, spindles, params, excl_stor, dyn_params, *args)
Create the device.
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Properties [hide private]

Inherited from object: __class__

Method Details [hide private]

__init__(self, unique_id, children, size, params, dyn_params, *args)
(Constructor)

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x.__init__(...) initializes x; see help(type(x)) for signature

Overrides: object.__init__
(inherited documentation)

Assemble(self)

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Assemble the device from its components.

Implementations of this method by child classes must ensure that:

  • after the device has been assembled, it knows its major/minor numbers; this allows other devices (usually parents) to probe correctly for their children
  • calling this method on an existing, in-use device is safe
  • if the device is already configured (and in an OK state), this method is idempotent

Create(cls, unique_id, children, size, spindles, params, excl_stor, dyn_params, *args)
Class Method

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Create the device.

If the device cannot be created, it will return None instead. Error messages go to the logging system.

Note that for some devices, the unique_id is used, and for other, the children. The idea is that these two, taken together, are enough for both creation and assembly (later).

Parameters:
  • unique_id (2-element tuple or list) - unique identifier; the details depend on the actual device type
  • children (list of BlockDev) - for hierarchical devices, the child devices
  • size (float) - size in MiB
  • spindles (int) - number of physical disk to dedicate to the device
  • params (dict) - device-specific options/parameters
  • excl_stor (bool) - whether exclusive_storage is active
  • dyn_params (dict) - dynamic parameters of the disk only valid for this node. As set by objects.Disk.UpdateDynamicDiskParams.
Returns: BlockDev
the created device, or None in case of an error

Remove(self)

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Remove this device.

This makes sense only for some of the device types: LV and file storage. Also note that if the device can't attach, the removal can't be completed.

Rename(self, new_id)

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Rename this device.

This may or may not make sense for a given device type.

Open(self, force=False)

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Make the device ready for use.

This makes the device ready for I/O. For now, just the DRBD devices need this.

The force parameter signifies that if the device has any kind of --force thing, it should be used, we know what we are doing.

Parameters:
  • force (boolean)

Shutdown(self)

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Shut down the device, freeing its children.

This undoes the `Assemble()` work, except for the child assembling; as such, the children on the device are still assembled after this call.

SetSyncParams(self, params)

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Adjust the synchronization parameters of the mirror.

In case this is not a mirroring device, this is no-op.

Parameters:
  • params - dictionary of LD level disk parameters related to the synchronization.
Returns: list
a list of error messages, emitted both by the current node and by children. An empty list means no errors.

PauseResumeSync(self, pause)

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Pause/Resume the sync of the mirror.

In case this is not a mirroring device, this is no-op.

Parameters:
  • pause (boolean) - Whether to pause or resume

GetSyncStatus(self)

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Returns the sync status of the device.

If this device is a mirroring device, this function returns the status of the mirror.

If sync_percent is None, it means the device is not syncing.

If estimated_time is None, it means we can't estimate the time needed, otherwise it's the time left in seconds.

If is_degraded is True, it means the device is missing redundancy. This is usually a sign that something went wrong in the device setup, if sync_percent is None.

The ldisk parameter represents the degradation of the local data. This is only valid for some devices, the rest will always return False (not degraded).

Returns: objects.BlockDevStatus

CombinedSyncStatus(self)

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Calculate the mirror status recursively for our children.

The return value is the same as for `GetSyncStatus()` except the minimum percent and maximum time are calculated across our children.

Returns: objects.BlockDevStatus

SetInfo(self, text)

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Update metadata with info text.

Only supported for some device types.

Grow(self, amount, dryrun, backingstore, excl_stor)

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Grow the block device.

Parameters:
  • amount (integer) - the amount (in mebibytes) to grow with
  • dryrun (boolean) - whether to execute the operation in simulation mode only, without actually increasing the size
  • backingstore - whether to execute the operation on backing storage only, or on "logical" storage only; e.g. DRBD is logical storage, whereas LVM, file, RBD are backing storage
  • excl_stor (boolean) - Whether exclusive_storage is active

GetActualSize(self)

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Return the actual disk size.

Note: the device needs to be active when this is called

GetActualSpindles(self)

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Return the actual number of spindles used.

This is not supported by all devices; if not supported, None is returned.

Note: the device needs to be active when this is called

GetActualDimensions(self)

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Return the actual disk size and number of spindles used.

Returns: tuple
(size, spindles); spindles is None when they are not supported

Note: the device needs to be active when this is called

GetUserspaceAccessUri(self, hypervisor)

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Return URIs hypervisors can use to access disks in userspace mode.

Returns: string
userspace device URI
Raises:

__repr__(self)
(Representation operator)

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repr(x)

Overrides: object.__repr__
(inherited documentation)