From 81eee9bd8cf3c94c564554e0d62b21a5efe45f7d Mon Sep 17 00:00:00 2001 From: Abhishek Lekshmanan Date: Tue, 16 Jun 2015 22:36:54 +0530 Subject: [PATCH] doc: explain about pgp num Explain the significance of pgp num & how it differs from pg num. Fixes: #10035 Reported-by: Loic Dachary Signed-off-by: Abhishek Lekshmanan --- doc/rados/operations/placement-groups.rst | 12 ++++++++---- doc/rados/operations/pools.rst | 3 +++ 2 files changed, 11 insertions(+), 4 deletions(-) diff --git a/doc/rados/operations/placement-groups.rst b/doc/rados/operations/placement-groups.rst index fe99269e6e4..2d77df6b97b 100644 --- a/doc/rados/operations/placement-groups.rst +++ b/doc/rados/operations/placement-groups.rst @@ -310,10 +310,14 @@ placement groups, execute the following:: ceph osd pool set {pool-name} pg_num {pg_num} Once you increase the number of placement groups, you must also -increase the number of placement groups for placement (``pgp_num``) before your -cluster will rebalance. The ``pgp_num`` should be equal to the ``pg_num``. -To increase the number of placement groups for placement, execute the -following:: +increase the number of placement groups for placement (``pgp_num``) +before your cluster will rebalance. The ``pgp_num`` will be the number of +placement groups that will be considered for placement by the CRUSH +algorithm. Increasing ``pg_num`` splits the placement groups but data +will not be migrated to the newer placement groups until placement +groups for placement, ie. ``pgp_num`` is increased. The ``pgp_num`` +should be equal to the ``pg_num``. To increase the number of +placement groups for placement, execute the following:: ceph osd pool set {pool-name} pgp_num {pgp_num} diff --git a/doc/rados/operations/pools.rst b/doc/rados/operations/pools.rst index 95ed7a6742a..46793cff598 100644 --- a/doc/rados/operations/pools.rst +++ b/doc/rados/operations/pools.rst @@ -53,6 +53,8 @@ Create a Pool Before creating pools, refer to the `Pool, PG and CRUSH Config Reference`_. Ideally, you should override the default value for the number of placement groups in your Ceph configuration file, as the default is NOT ideal. +For details on placement group numbers refer to `setting the number of placement groups`_ + For example:: osd pool default pg num = 100 @@ -568,3 +570,4 @@ a size of 3). .. _Pool, PG and CRUSH Config Reference: ../../configuration/pool-pg-config-ref .. _Bloom Filter: http://en.wikipedia.org/wiki/Bloom_filter +.. _setting the number of placement groups: ../placement-groups#set-the-number-of-placement-groups -- 2.47.3