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https://github.com/ceph/ceph
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75 lines
935 B
ReStructuredText
75 lines
935 B
ReStructuredText
RBD Incremental Backup
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======================
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This is a simple streaming file format for representing a diff between
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two snapshots (or a snapshot and the head) of an RBD image.
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Header
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~~~~~~
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"rbd diff v1\n"
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Metadata records
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~~~~~~~~~~~~~~~~
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Every record has a one byte "tag" that identifies the record type,
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followed by some other data.
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Metadata records come in the first part of the image. Order is not
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important, as long as all the metadata records come before the data
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records.
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From snap
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---------
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u8: 'f'
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le32: snap name length
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snap name
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To snap
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-------
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u8: 't'
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le32: snap name length
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snap name
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Size
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----
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u8: 's'
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u64: (ending) image size
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Data Records
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~~~~~~~~~~~~
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These records come in the second part of the sequence.
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Updated data
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------------
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u8: 'w'
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le64: offset
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le64: length
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length bytes of actual data
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Zero data
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---------
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u8: 'z'
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le64: offset
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le64: length
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Final Record
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~~~~~~~~~~~~
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End
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---
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u8: 'e'
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