From 6c970133e0a065cb46c655e918c1d3f9410678e4 Mon Sep 17 00:00:00 2001 From: Alfredo Deza Date: Tue, 15 Aug 2017 11:16:56 -0400 Subject: [PATCH] doc/rados/operations add ref label for placement group number Signed-off-by: Alfredo Deza --- doc/rados/operations/placement-groups.rst | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/doc/rados/operations/placement-groups.rst b/doc/rados/operations/placement-groups.rst index fee833ad0c6..b0c6e329d62 100644 --- a/doc/rados/operations/placement-groups.rst +++ b/doc/rados/operations/placement-groups.rst @@ -23,7 +23,7 @@ calculated automatically. Here are a few values commonly used: - If you have more than 50 OSDs, you need to understand the tradeoffs and how to calculate the ``pg_num`` value by yourself -- For calculating ``pg_num`` value by yourself please take help of `pgcalc`_ tool +- For calculating ``pg_num`` value by yourself please take help of `pgcalc`_ tool As the number of OSDs increases, chosing the right value for pg_num becomes more important because it has a significant influence on the @@ -191,7 +191,7 @@ will degrade ~4 (i.e. ~75 / 19 placement groups being recovered) instead of ~17 and the third OSD lost will only lose data if it is one of the four OSDs containing the surviving copy. In other words, if the probability of losing one OSD is 0.0001% during the recovery time -frame, it goes from 17 * 10 * 0.0001% in the cluster with 10 OSDs to 4 * 20 * +frame, it goes from 17 * 10 * 0.0001% in the cluster with 10 OSDs to 4 * 20 * 0.0001% in the cluster with 20 OSDs. In a nutshell, more OSDs mean faster recovery and a lower risk of @@ -250,6 +250,8 @@ they exist. Minimizing the number of placement groups saves significant amounts of resources. +.. _choosing-number-of-placement-groups: + Choosing the number of Placement Groups ======================================= @@ -412,7 +414,7 @@ than others (for example, those PGs may hold data for images used by running machines and other PGs may be used by inactive machines/less relevant data). In that case, you may want to prioritize recovery of those groups so performance and/or availability of data stored on those groups is restored -earlier. To do this (mark particular placement group(s) as prioritized during +earlier. To do this (mark particular placement group(s) as prioritized during backfill or recovery), execute the following:: ceph pg force-recovery {pg-id} [{pg-id #2}] [{pg-id #3} ...] -- 2.39.5