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| author | zdover23 <1445107+zdover23@users.noreply.github.com> | 2022-11-25 08:12:05 +0100 |
|---|---|---|
| committer | GitHub <noreply@github.com> | 2022-11-25 08:12:05 +0100 |
| commit | 385bbd5144615d81866f97de604540ef08e23fc9 (patch) | |
| tree | 9cfa051a1545340cd34a90001b1ba82e3e3b2931 | |
| parent | Merge pull request #48927 from neesingh-rh/fix_58028 (diff) | |
| parent | doc/rados: cleanup "erasure code profiles" (diff) | |
| download | ceph-385bbd5144615d81866f97de604540ef08e23fc9.tar.xz ceph-385bbd5144615d81866f97de604540ef08e23fc9.zip | |
Merge pull request #49046 from zdover23/wip-doc-2022-11-25-rados-ops-erasure-code-profiles
doc/rados: cleanup "erasure code profiles"
Reviewed-by: Anthony D'Atri <anthony.datri@gmail.com>
| -rw-r--r-- | doc/rados/operations/erasure-code.rst | 19 |
1 files changed, 11 insertions, 8 deletions
diff --git a/doc/rados/operations/erasure-code.rst b/doc/rados/operations/erasure-code.rst index 288369526db..ca267594135 100644 --- a/doc/rados/operations/erasure-code.rst +++ b/doc/rados/operations/erasure-code.rst @@ -50,10 +50,10 @@ requires at least three hosts: Erasure code profiles --------------------- -The default erasure code profile sustains the loss of a two OSDs. It -is equivalent to a replicated pool of size three but requires 2TB -instead of 3TB to store 1TB of data. The default profile can be -displayed with: +The default erasure code profile can sustain the loss of two OSDs. This erasure +code profile is equivalent to a replicated pool of size three, but requires +2TB to store 1TB of data instead of 3TB to store 1TB of data. The default +profile can be displayed with this command: .. prompt:: bash $ @@ -67,13 +67,16 @@ displayed with: crush-failure-domain=host technique=reed_sol_van -Choosing the right profile is important because it cannot be modified -after the pool is created: a new pool with a different profile needs -to be created and all objects from the previous pool moved to the new. +Choosing the right profile is important because the profile cannot be modified +after the pool is created. If you find that you need an erasure-coded pool with +a profile different than the one you have created, you must create a new pool +with a different (and presumably more carefully-considered) profile. When the +new pool is created, all objects from the wrongly-configured pool must be moved +to the newly-created pool. There is no way to alter the profile of a pool after its creation. The most important parameters of the profile are *K*, *M* and *crush-failure-domain* because they define the storage overhead and -the data durability. For instance, if the desired architecture must +the data durability. For example, if the desired architecture must sustain the loss of two racks with a storage overhead of 67% overhead, the following profile can be defined: |