54 lines
1.6 KiB
ReStructuredText
54 lines
1.6 KiB
ReStructuredText
Feature Flags
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=============
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ZFS on-disk formats were originally versioned with a single number,
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which increased whenever the format changed. The numbered approach was
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suitable when development of ZFS was driven by a single organisation.
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For distributed development of OpenZFS, version numbering was
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unsuitable. Any change to the number would have required agreement,
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across all implementations, of each change to the on-disk format.
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OpenZFS feature flags – an alternative to traditional version numbering
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– allow **a uniquely named pool property for each change to the on-disk
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format**. This approach supports:
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- format changes that are independent
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- format changes that depend on each other.
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Compatibility
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-------------
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Where all *features* that are used by a pool are supported by multiple
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implementations of OpenZFS, the on-disk format is portable across those
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implementations.
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Features that are exclusive when enabled should be periodically ported
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to all distributions.
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Reference materials
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-------------------
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`ZFS Feature Flags <http://web.archive.org/web/20160419064650/http://blog.delphix.com/csiden/files/2012/01/ZFS_Feature_Flags.pdf>`_
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(Christopher Siden, 2012-01, in the Internet
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Archive Wayback Machine) in particular: "… Legacy version numbers still
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exist for pool versions 1-28 …".
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`zpool-features(7) man page <../man/7/zpool-features.7.html>`_ - OpenZFS
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`zpool-features <http://illumos.org/man/5/zpool-features>`__ (5) – illumos
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Feature flags implementation per OS
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-----------------------------------
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.. raw:: html
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<div class="man_container">
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.. raw:: html
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:file: ../_build/zfs_feature_matrix.html
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.. raw:: html
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</div>
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