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doc/rados: cleanup "erasure code profiles"

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Improve the grammar of "Erasure Code Profiles".

Signed-off-by: Zac Dover <zac.dover@gmail.com>
This commit is contained in:
Zac Dover 2022-11-25 04:41:12 +10:00
parent 25c18c5eba
commit ae7337bf5e
1 changed files with 11 additions and 8 deletions
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19
doc/rados/operations/erasure-code.rst
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@ -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: