ceph/doc/rados/operations/erasure-code-isa.rst

   1 =======================
   2 ISA erasure code plugin
   3 =======================
   4
   5 The *isa* plugin encapsulates the `ISA
   6 <https://01.org/intel%C2%AE-storage-acceleration-library-open-source-version/>`_
   7 library. It only runs on Intel processors.
   8
   9 Create an isa profile
  10 =====================
  11
  12 To create a new *isa* erasure code profile::
  13
  14         ceph osd erasure-code-profile set {name} \
  15              plugin=isa \
  16              technique={reed_sol_van|cauchy} \
  17              [k={data-chunks}] \
  18              [m={coding-chunks}] \
  19              [crush-root={root}] \
  20              [crush-failure-domain={bucket-type}] \
  21              [crush-device-class={device-class}] \
  22              [directory={directory}] \
  23              [--force]
  24
  25 Where:
  26
  27 ``k={data chunks}``
  28
  29 :Description: Each object is split in **data-chunks** parts,
  30               each stored on a different OSD.
  31
  32 :Type: Integer
  33 :Required: No.
  34 :Default: 7
  35
  36 ``m={coding-chunks}``
  37
  38 :Description: Compute **coding chunks** for each object and store them
  39               on different OSDs. The number of coding chunks is also
  40               the number of OSDs that can be down without losing data.
  41
  42 :Type: Integer
  43 :Required: No.
  44 :Default: 3
  45
  46 ``technique={reed_sol_van|cauchy}``
  47
  48 :Description: The ISA plugin comes in two `Reed Solomon
  49               <https://en.wikipedia.org/wiki/Reed%E2%80%93Solomon_error_correction>`_
  50               forms. If *reed_sol_van* is set, it is `Vandermonde
  51               <https://en.wikipedia.org/wiki/Vandermonde_matrix>`_, if
  52               *cauchy* is set, it is `Cauchy
  53               <https://en.wikipedia.org/wiki/Cauchy_matrix>`_.
  54
  55 :Type: String
  56 :Required: No.
  57 :Default: reed_sol_van
  58
  59 ``crush-root={root}``
  60
  61 :Description: The name of the crush bucket used for the first step of
  62               the ruleset. For intance **step take default**.
  63
  64 :Type: String
  65 :Required: No.
  66 :Default: default
  67
  68 ``crush-failure-domain={bucket-type}``
  69
  70 :Description: Ensure that no two chunks are in a bucket with the same
  71               failure domain. For instance, if the failure domain is
  72               **host** no two chunks will be stored on the same
  73               host. It is used to create a ruleset step such as **step
  74               chooseleaf host**.
  75
  76 :Type: String
  77 :Required: No.
  78 :Default: host
  79
  80 ``crush-device-class={device-class}``
  81
  82 :Description: Restrict placement to devices of a specific class (e.g.,
  83               ``ssd`` or ``hdd``), using the crush device class names
  84               in the CRUSH map.
  85
  86 :Type: String
  87 :Required: No.
  88 :Default:
  89
  90 ``directory={directory}``
  91
  92 :Description: Set the **directory** name from which the erasure code
  93               plugin is loaded.
  94
  95 :Type: String
  96 :Required: No.
  97 :Default: /usr/lib/ceph/erasure-code
  98
  99 ``--force``
 100
 101 :Description: Override an existing profile by the same name.
 102
 103 :Type: String
 104 :Required: No.
 105