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https://github.com/ceph/ceph
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76 lines
3.2 KiB
ReStructuredText
76 lines
3.2 KiB
ReStructuredText
==============================
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RBD Kernel Object Operations
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==============================
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.. important:: To use kernel object operations, you must have a running Ceph cluster.
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Add a Block Device
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------------------
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To add an RBD image as a kernel object, first load the Ceph RBD module::
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modprobe rbd
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Map the RBD image to the kernel object with ``add``, specifying the IP address
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of the monitor, the user name, and the RBD image name as follows::
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echo "{mon-ip-address} name={user-name} rbd {image-name}" | sudo tee /sys/bus/rbd/add
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For example::
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echo "10.20.30.40 name=admin rbd foo" | sudo tee /sys/bus/rbd/add
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If you use ``cephx`` authentication, you must also specify a secret. ::
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echo "10.20.30.40 name=admin,secret=/path/to/secret rbd foo" | sudo tee /sys/bus/rbd/add
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A kernel block device resides under the ``/sys/bus/rbd/devices`` directory and
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provides the following functions:
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+------------------+------------------------------------------------------------+
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| Function | Description |
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+==================+============================================================+
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| ``client_id`` | Returns the client ID of the given device ID. |
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+------------------+------------------------------------------------------------+
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| ``create_snap`` | Creates a snap from a snap name and a device ID. |
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+------------------+------------------------------------------------------------+
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| ``current_snap`` | Returns the most recent snap for the given device ID. |
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+------------------+------------------------------------------------------------+
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| ``major`` | |
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+------------------+------------------------------------------------------------+
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| ``name`` | Returns the RBD image name of the device ID. |
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+------------------+------------------------------------------------------------+
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| ``pool`` | Returns the pool source of the device ID. |
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+------------------+------------------------------------------------------------+
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| ``refresh`` | Refreshes the given device with the SDs. |
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+------------------+------------------------------------------------------------+
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| ``size`` | Returns the size of the device. |
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+------------------+------------------------------------------------------------+
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| ``uevent`` | |
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+------------------+------------------------------------------------------------+
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List Block Devices
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------------------
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Images are mounted as devices sequentially starting from ``0``. To list the
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devices mounted, execute the following::
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ls /sys/bus/rbd/devices
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Removing a Block Device
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-----------------------
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To remove an RBD image, specify its index and use ``tee`` to call ``remove`` as
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follows, but replace ``{device-number}`` with the number of the device you want
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to remove::
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echo {device-number} | sudo tee /sys/bus/rbd/remove
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Creating a Snapshot
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-------------------
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To create a snapshot of a device, you must specify the device number. ::
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echo sn1 | sudo tee /sys/bus/rbd/devices/0{device-number}/create_snap
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