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Diffstat (limited to 'docs/interop/bitmaps.rst')
| -rw-r--r-- | docs/interop/bitmaps.rst | 291 |
1 files changed, 218 insertions, 73 deletions
diff --git a/docs/interop/bitmaps.rst b/docs/interop/bitmaps.rst index 059ad67929..ddf8947d54 100644 --- a/docs/interop/bitmaps.rst +++ b/docs/interop/bitmaps.rst @@ -166,9 +166,9 @@ Basic QMP Usage --------------- The primary interface to manipulating bitmap objects is via the QMP -interface. If you are not familiar, see docs/interop/qmp-intro.txt for a broad -overview, and `qemu-qmp-ref <qemu-qmp-ref.html>`_ for a full reference of all -QMP commands. +interface. If you are not familiar, see the :doc:`qmp-spec` for the +protocol, and :doc:`qemu-qmp-ref` for a full reference of all QMP +commands. Supported Commands ~~~~~~~~~~~~~~~~~~ @@ -539,12 +539,11 @@ other partial disk images on top of a base image to reconstruct a full backup from the point in time at which the incremental backup was issued. The "Push Model" here references the fact that QEMU is "pushing" the modified -blocks out to a destination. We will be using the `drive-backup -<qemu-qmp-ref.html#index-drive_002dbackup>`_ and `blockdev-backup -<qemu-qmp-ref.html#index-blockdev_002dbackup>`_ QMP commands to create both +blocks out to a destination. We will be using the `blockdev-backup +<qemu-qmp-ref.html#index-blockdev_002dbackup>`_ QMP command to create both full and incremental backups. -Both of these commands are jobs, which have their own QMP API for querying and +The command is a background job, which has its own QMP API for querying and management documented in `Background jobs <qemu-qmp-ref.html#Background-jobs>`_. @@ -557,6 +556,10 @@ create a new incremental backup chain attached to a drive. This example creates a new, full backup of "drive0" and accompanies it with a new, empty bitmap that records writes from this point in time forward. +The target can be created with the help of `blockdev-add +<qemu-qmp-ref.html#index-blockdev_002dadd>`_ or `blockdev-create +<qemu-qmp-ref.html#index-blockdev_002dcreate>`_ command. + .. note:: Any new writes that happen after this command is issued, even while the backup job runs, will be written locally and not to the backup destination. These writes will be recorded in the bitmap @@ -576,12 +579,11 @@ new, empty bitmap that records writes from this point in time forward. } }, { - "type": "drive-backup", + "type": "blockdev-backup", "data": { "device": "drive0", - "target": "/path/to/drive0.full.qcow2", - "sync": "full", - "format": "qcow2" + "target": "target0", + "sync": "full" } } ] @@ -664,12 +666,11 @@ use a transaction to reset the bitmap while making a new full backup: } }, { - "type": "drive-backup", + "type": "blockdev-backup", "data": { "device": "drive0", - "target": "/path/to/drive0.new_full.qcow2", - "sync": "full", - "format": "qcow2" + "target": "target0", + "sync": "full" } } ] @@ -728,19 +729,35 @@ Example: First Incremental Backup $ qemu-img create -f qcow2 drive0.inc0.qcow2 \ -b drive0.full.qcow2 -F qcow2 +#. Add target block node: + + .. code-block:: QMP + + -> { + "execute": "blockdev-add", + "arguments": { + "node-name": "target0", + "driver": "qcow2", + "file": { + "driver": "file", + "filename": "drive0.inc0.qcow2" + } + } + } + + <- { "return": {} } + #. Issue an incremental backup command: .. code-block:: QMP -> { - "execute": "drive-backup", + "execute": "blockdev-backup", "arguments": { "device": "drive0", "bitmap": "bitmap0", - "target": "drive0.inc0.qcow2", - "format": "qcow2", - "sync": "incremental", - "mode": "existing" + "target": "target0", + "sync": "incremental" } } @@ -785,20 +802,36 @@ Example: Second Incremental Backup $ qemu-img create -f qcow2 drive0.inc1.qcow2 \ -b drive0.inc0.qcow2 -F qcow2 +#. Add target block node: + + .. code-block:: QMP + + -> { + "execute": "blockdev-add", + "arguments": { + "node-name": "target0", + "driver": "qcow2", + "file": { + "driver": "file", + "filename": "drive0.inc1.qcow2" + } + } + } + + <- { "return": {} } + #. Issue a new incremental backup command. The only difference here is that we have changed the target image below. .. code-block:: QMP -> { - "execute": "drive-backup", + "execute": "blockdev-backup", "arguments": { "device": "drive0", "bitmap": "bitmap0", - "target": "drive0.inc1.qcow2", - "format": "qcow2", - "sync": "incremental", - "mode": "existing" + "target": "target0", + "sync": "incremental" } } @@ -866,20 +899,36 @@ image: file for you, but you lose control over format options like compatibility and preallocation presets. +#. Add target block node: + + .. code-block:: QMP + + -> { + "execute": "blockdev-add", + "arguments": { + "node-name": "target0", + "driver": "qcow2", + "file": { + "driver": "file", + "filename": "drive0.inc2.qcow2" + } + } + } + + <- { "return": {} } + #. Issue a new incremental backup command. Apart from the new destination image, there is no difference from the last two examples. .. code-block:: QMP -> { - "execute": "drive-backup", + "execute": "blockdev-backup", "arguments": { "device": "drive0", "bitmap": "bitmap0", - "target": "drive0.inc2.qcow2", - "format": "qcow2", - "sync": "incremental", - "mode": "existing" + "target": "target0", + "sync": "incremental" } } @@ -930,6 +979,38 @@ point in time. $ qemu-img create -f qcow2 drive0.full.qcow2 64G $ qemu-img create -f qcow2 drive1.full.qcow2 64G +#. Add target block nodes: + + .. code-block:: QMP + + -> { + "execute": "blockdev-add", + "arguments": { + "node-name": "target0", + "driver": "qcow2", + "file": { + "driver": "file", + "filename": "drive0.full.qcow2" + } + } + } + + <- { "return": {} } + + -> { + "execute": "blockdev-add", + "arguments": { + "node-name": "target1", + "driver": "qcow2", + "file": { + "driver": "file", + "filename": "drive1.full.qcow2" + } + } + } + + <- { "return": {} } + #. Create a full (anchor) backup for each drive, with accompanying bitmaps: .. code-block:: QMP @@ -953,21 +1034,19 @@ point in time. } }, { - "type": "drive-backup", + "type": "blockdev-backup", "data": { "device": "drive0", - "target": "/path/to/drive0.full.qcow2", - "sync": "full", - "format": "qcow2" + "target": "target0", + "sync": "full" } }, { - "type": "drive-backup", + "type": "blockdev-backup", "data": { "device": "drive1", - "target": "/path/to/drive1.full.qcow2", - "sync": "full", - "format": "qcow2" + "target": "target1", + "sync": "full" } } ] @@ -1016,6 +1095,38 @@ point in time. $ qemu-img create -f qcow2 drive1.inc0.qcow2 \ -b drive1.full.qcow2 -F qcow2 +#. Add target block nodes: + + .. code-block:: QMP + + -> { + "execute": "blockdev-add", + "arguments": { + "node-name": "target0", + "driver": "qcow2", + "file": { + "driver": "file", + "filename": "drive0.inc0.qcow2" + } + } + } + + <- { "return": {} } + + -> { + "execute": "blockdev-add", + "arguments": { + "node-name": "target1", + "driver": "qcow2", + "file": { + "driver": "file", + "filename": "drive1.inc0.qcow2" + } + } + } + + <- { "return": {} } + #. Issue a multi-drive incremental push backup transaction: .. code-block:: QMP @@ -1025,25 +1136,21 @@ point in time. "arguments": { "actions": [ { - "type": "drive-backup", + "type": "blockev-backup", "data": { "device": "drive0", "bitmap": "bitmap0", - "format": "qcow2", - "mode": "existing", "sync": "incremental", - "target": "drive0.inc0.qcow2" + "target": "target0" } }, { - "type": "drive-backup", + "type": "blockdev-backup", "data": { "device": "drive1", "bitmap": "bitmap0", - "format": "qcow2", - "mode": "existing", "sync": "incremental", - "target": "drive1.inc0.qcow2" + "target": "target1" } }, ] @@ -1119,19 +1226,35 @@ described above. This example demonstrates the single-job failure case: $ qemu-img create -f qcow2 drive0.inc0.qcow2 \ -b drive0.full.qcow2 -F qcow2 +#. Add target block node: + + .. code-block:: QMP + + -> { + "execute": "blockdev-add", + "arguments": { + "node-name": "target0", + "driver": "qcow2", + "file": { + "driver": "file", + "filename": "drive0.inc0.qcow2" + } + } + } + + <- { "return": {} } + #. Attempt to create an incremental backup via QMP: .. code-block:: QMP -> { - "execute": "drive-backup", + "execute": "blockdev-backup", "arguments": { "device": "drive0", "bitmap": "bitmap0", - "target": "drive0.inc0.qcow2", - "format": "qcow2", - "sync": "incremental", - "mode": "existing" + "target": "target0", + "sync": "incremental" } } @@ -1164,6 +1287,19 @@ described above. This example demonstrates the single-job failure case: "event": "BLOCK_JOB_COMPLETED" } +#. Remove target node: + + .. code-block:: QMP + + -> { + "execute": "blockdev-del", + "arguments": { + "node-name": "target0", + } + } + + <- { "return": {} } + #. Delete the failed image, and re-create it. .. code:: bash @@ -1172,20 +1308,36 @@ described above. This example demonstrates the single-job failure case: $ qemu-img create -f qcow2 drive0.inc0.qcow2 \ -b drive0.full.qcow2 -F qcow2 +#. Add target block node: + + .. code-block:: QMP + + -> { + "execute": "blockdev-add", + "arguments": { + "node-name": "target0", + "driver": "qcow2", + "file": { + "driver": "file", + "filename": "drive0.inc0.qcow2" + } + } + } + + <- { "return": {} } + #. Retry the command after fixing the underlying problem, such as freeing up space on the backup volume: .. code-block:: QMP -> { - "execute": "drive-backup", + "execute": "blockdev-backup", "arguments": { "device": "drive0", "bitmap": "bitmap0", - "target": "drive0.inc0.qcow2", - "format": "qcow2", - "sync": "incremental", - "mode": "existing" + "target": "target0", + "sync": "incremental" } } @@ -1210,7 +1362,8 @@ described above. This example demonstrates the single-job failure case: Example: Partial Transactional Failures ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -QMP commands like `drive-backup <qemu-qmp-ref.html#index-drive_002dbackup>`_ +QMP commands like `blockdev-backup +<qemu-qmp-ref.html#index-blockdev_002dbackup>`_ conceptually only start a job, and so transactions containing these commands may succeed even if the job it created later fails. This might have surprising interactions with notions of how a "transaction" ought to behave. @@ -1240,25 +1393,21 @@ and one succeeds: "arguments": { "actions": [ { - "type": "drive-backup", + "type": "blockdev-backup", "data": { "device": "drive0", "bitmap": "bitmap0", - "format": "qcow2", - "mode": "existing", "sync": "incremental", - "target": "drive0.inc0.qcow2" + "target": "target0" } }, { - "type": "drive-backup", + "type": "blockdev-backup", "data": { "device": "drive1", "bitmap": "bitmap0", - "format": "qcow2", - "mode": "existing", "sync": "incremental", - "target": "drive1.inc0.qcow2" + "target": "target1" } }] } @@ -1375,25 +1524,21 @@ applied: }, "actions": [ { - "type": "drive-backup", + "type": "blockdev-backup", "data": { "device": "drive0", "bitmap": "bitmap0", - "format": "qcow2", - "mode": "existing", "sync": "incremental", - "target": "drive0.inc0.qcow2" + "target": "target0" } }, { - "type": "drive-backup", + "type": "blockdev-backup", "data": { "device": "drive1", "bitmap": "bitmap0", - "format": "qcow2", - "mode": "existing", "sync": "incremental", - "target": "drive1.inc0.qcow2" + "target": "target1" } }] } |