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Since kraken, Ceph enforces a 1:1 correspondence between CRUSH ruleset and CRUSH rule, so effectively ruleset and rule are the same thing, although the term "ruleset" still survives - notably in the CRUSH rule itself, where it effectively denotes the number of the rule. This commit updates the documentation to more faithfully reflect the current state of the code. Fixes: http://tracker.ceph.com/issues/20559 Signed-off-by: Nathan Cutler <ncutler@suse.com>
106 lines
2.7 KiB
ReStructuredText
106 lines
2.7 KiB
ReStructuredText
=======================
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ISA erasure code plugin
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=======================
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The *isa* plugin encapsulates the `ISA
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<https://01.org/intel%C2%AE-storage-acceleration-library-open-source-version/>`_
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library. It only runs on Intel processors.
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Create an isa profile
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=====================
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To create a new *isa* erasure code profile::
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ceph osd erasure-code-profile set {name} \
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plugin=isa \
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technique={reed_sol_van|cauchy} \
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[k={data-chunks}] \
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[m={coding-chunks}] \
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[crush-root={root}] \
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[crush-failure-domain={bucket-type}] \
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[crush-device-class={device-class}] \
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[directory={directory}] \
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[--force]
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Where:
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``k={data chunks}``
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:Description: Each object is split in **data-chunks** parts,
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each stored on a different OSD.
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:Type: Integer
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:Required: No.
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:Default: 7
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``m={coding-chunks}``
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:Description: Compute **coding chunks** for each object and store them
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on different OSDs. The number of coding chunks is also
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the number of OSDs that can be down without losing data.
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:Type: Integer
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:Required: No.
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:Default: 3
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``technique={reed_sol_van|cauchy}``
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:Description: The ISA plugin comes in two `Reed Solomon
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<https://en.wikipedia.org/wiki/Reed%E2%80%93Solomon_error_correction>`_
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forms. If *reed_sol_van* is set, it is `Vandermonde
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<https://en.wikipedia.org/wiki/Vandermonde_matrix>`_, if
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*cauchy* is set, it is `Cauchy
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<https://en.wikipedia.org/wiki/Cauchy_matrix>`_.
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:Type: String
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:Required: No.
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:Default: reed_sol_van
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``crush-root={root}``
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:Description: The name of the crush bucket used for the first step of
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the CRUSH rule. For intance **step take default**.
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:Type: String
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:Required: No.
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:Default: default
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``crush-failure-domain={bucket-type}``
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:Description: Ensure that no two chunks are in a bucket with the same
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failure domain. For instance, if the failure domain is
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**host** no two chunks will be stored on the same
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host. It is used to create a CRUSH rule step such as **step
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chooseleaf host**.
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:Type: String
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:Required: No.
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:Default: host
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``crush-device-class={device-class}``
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:Description: Restrict placement to devices of a specific class (e.g.,
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``ssd`` or ``hdd``), using the crush device class names
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in the CRUSH map.
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:Type: String
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:Required: No.
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:Default:
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``directory={directory}``
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:Description: Set the **directory** name from which the erasure code
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plugin is loaded.
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:Type: String
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:Required: No.
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:Default: /usr/lib/ceph/erasure-code
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``--force``
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:Description: Override an existing profile by the same name.
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:Type: String
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:Required: No.
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