Notice

This document is for a development version of Ceph.

ISA erasure code plugin

The isa plugin is the default for Ceph erasure coded pools. The isa plugin encapsulates the ISA library.

Create an isa profile

To create a new isa erasure code profile:

ceph osd erasure-code-profile set {name} \
  plugin=isa \
  technique={reed_sol_van|cauchy} \
  [k={data-chunks}] \
  [m={coding-chunks}] \
  [crush-root={root}] \
  [crush-failure-domain={bucket-type}] \
  [crush-device-class={device-class}] \
  [directory={directory}] \
  [--force]

Where:

k={data chunks}

Description:

Each object is split in data-chunks parts, each stored on a different OSD.

Type:

Integer

Required:

No.

Default:

7

m={coding-chunks}

Description:

Compute coding chunks for each object and store them on different OSDs. The number of coding chunks is also the number of OSDs that can be down without losing data.

Type:

Integer

Required:

No.

Default:

3

technique={reed_sol_van|cauchy}

Description:

The ISA plugin comes in two Reed Solomon forms. If reed_sol_van is set, it is Vandermonde, if cauchy is set, it is Cauchy.

Type:

String

Required:

No.

Default:

reed_sol_van

crush-root={root}

Description:

The name of the crush bucket used for the first step of the CRUSH rule. For instance step take default.

Type:

String

Required:

No.

Default:

default

crush-failure-domain={bucket-type}

Description:

Ensure that no two chunks are in a bucket with the same failure domain. For instance, if the failure domain is host no two chunks will be stored on the same host. It is used to create a CRUSH rule step such as step chooseleaf host.

Type:

String

Required:

No.

Default:

host

crush-device-class={device-class}

Description:

Restrict placement to devices of a specific class (e.g., ssd or hdd), using the crush device class names in the CRUSH map.

Type:

String

Required:

No.

Default:

directory={directory}

Description:

Set the directory name from which the erasure code plugin is loaded.

Type:

String

Required:

No.

Default:

/usr/lib/ceph/erasure-code

--force

Description:

Override an existing profile by the same name.

Type:

String

Required:

No.

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