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Diffstat (limited to 'doc/rados/operations/erasure-code-profile.rst')
| -rw-r--r-- | doc/rados/operations/erasure-code-profile.rst | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/doc/rados/operations/erasure-code-profile.rst b/doc/rados/operations/erasure-code-profile.rst index 3a73eb344ed..45b071f8ad7 100644 --- a/doc/rados/operations/erasure-code-profile.rst +++ b/doc/rados/operations/erasure-code-profile.rst @@ -8,10 +8,12 @@ Erasure code is defined by a **profile** and is used when creating an erasure coded pool and the associated CRUSH rule. The **default** erasure code profile (which is created when the Ceph -cluster is initialized) provides the same level of redundancy as two -copies but requires 25% less disk space. It is described as a profile -with **k=2** and **m=1**, meaning the information is spread over three -OSD (k+m == 3) and one of them can be lost. +cluster is initialized) will split the data into 2 equal-sized chunks, +and have 2 parity chunks of the same size. It will take as much space +in the cluster as a 2-replica pool but can sustain the data loss of 2 +chunks out of 4. It is described as a profile with **k=2** and **m=2**, +meaning the information is spread over four OSD (k+m == 4) and two of +them can be lost. To improve redundancy without increasing raw storage requirements, a new profile can be created. For instance, a profile with **k=10** and |