From d587907dd47c6843d53cb91520b4f8ed2137a0be Mon Sep 17 00:00:00 2001 From: Zac Dover Date: Fri, 16 Dec 2022 11:07:51 +1000 Subject: [PATCH] doc/rados: clarify default EC pool from simplest Distinguish between the default erasure-coded pool (k=2 m=2) and the simplest erasure-coded pool (k=2 m=1). Signed-off-by: Zac Dover (cherry picked from commit 63c27ab8e746127b89120d4c47b427d13433758c) --- doc/rados/operations/erasure-code.rst | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/doc/rados/operations/erasure-code.rst b/doc/rados/operations/erasure-code.rst index ca26759413591..1dea23c35168d 100644 --- a/doc/rados/operations/erasure-code.rst +++ b/doc/rados/operations/erasure-code.rst @@ -67,6 +67,16 @@ profile can be displayed with this command: crush-failure-domain=host technique=reed_sol_van +.. note:: + The default erasure-coded pool, the profile of which is displayed here, is + not the same as the simplest erasure-coded pool. + + The default erasure-coded pool has two data chunks (k) and two coding chunks + (m). The profile of the default erasure-coded pool is "k=2 m=2". + + The simplest erasure-coded pool has two data chunks (k) and one coding chunk + (m). The profile of the simplest erasure-coded pool is "k=2 m=1". + 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 -- 2.39.5