From e553d095d6eee241c381acfe9f097d283cf7c7bc Mon Sep 17 00:00:00 2001 From: Trent Lloyd Date: Tue, 7 Jul 2020 14:13:29 +0800 Subject: [PATCH] Remove rbd_store_chunk_size=8 reverting to default We have shipped rbd_store_chunk_size=8 in our glance configuration for a very long time, this value was sometimes suggested in older upstream documentation and has the effect of halving the number of rados objects used to store glance images. When using qcow2 images in ceph the created VM volume will have an rbd_store_chunk_size=4 (the default) however in modern clouds when images are in the raw format we will use copy-on-write cloning from the image to the volume, which means all such VM volumes inherit rbd_store_chunk_size=8 from the parent. This has negative performance implications for working volumes as there are object-wide locks that now cover twice as much data and a wider chunk of sequential disk storage will hit the same OSD. Any overhead benefit of using objects only double the size (and thus half in number) is very likely long relegated to history given the number of volumes we're likely to have in a cloud versus base images, so there doesn't seem to be any benefit to this setting and outside of a few glance documents this rbd option is not documented anywhere I can find as a suggestion or with any evidence of an advantage of performance improvement from storing images this way. Remove rbd_store_chunk_size=8 from all configuration files so that it reverts to the default of 4. Existing images (and old or new dependent volumes of them) will maintain the existing rbd_store_chunk_size=8 and continue to work correctly. New images will be created with the new rbd_store_chunk_size=4. Change-Id: I5f6801c418430bbdcda53b94fcd51ed2fc230b68 --- templates/icehouse/glance-api.conf | 1 - templates/juno/glance-api.conf | 1 - templates/kilo/glance-api.conf | 1 - templates/mitaka/glance-api.conf | 1 - templates/ocata/glance-api.conf | 1 - templates/queens/glance-api.conf | 1 - templates/stein/glance-api.conf | 1 - 7 files changed, 7 deletions(-) diff --git a/templates/icehouse/glance-api.conf b/templates/icehouse/glance-api.conf index 7a298517..8f60108f 100644 --- a/templates/icehouse/glance-api.conf +++ b/templates/icehouse/glance-api.conf @@ -68,7 +68,6 @@ swift_enable_snet = False rbd_store_ceph_conf = /etc/ceph/ceph.conf rbd_store_user = {{ rbd_user }} rbd_store_pool = {{ rbd_pool }} -rbd_store_chunk_size = 8 {% endif -%} delayed_delete = False diff --git a/templates/juno/glance-api.conf b/templates/juno/glance-api.conf index 56e287a2..c35b5adb 100644 --- a/templates/juno/glance-api.conf +++ b/templates/juno/glance-api.conf @@ -71,7 +71,6 @@ swift_enable_snet = False rbd_store_ceph_conf = /etc/ceph/ceph.conf rbd_store_user = {{ rbd_user }} rbd_store_pool = {{ rbd_pool }} -rbd_store_chunk_size = 8 {% endif -%} delayed_delete = False diff --git a/templates/kilo/glance-api.conf b/templates/kilo/glance-api.conf index a0bab4e5..f21b70c2 100644 --- a/templates/kilo/glance-api.conf +++ b/templates/kilo/glance-api.conf @@ -77,7 +77,6 @@ swift_enable_snet = False rbd_store_ceph_conf = /etc/ceph/ceph.conf rbd_store_user = {{ rbd_user }} rbd_store_pool = {{ rbd_pool }} -rbd_store_chunk_size = 8 {% endif -%} [image_format] diff --git a/templates/mitaka/glance-api.conf b/templates/mitaka/glance-api.conf index 4250a6a3..2ce20709 100644 --- a/templates/mitaka/glance-api.conf +++ b/templates/mitaka/glance-api.conf @@ -69,7 +69,6 @@ swift_store_create_container_on_put = true rbd_store_ceph_conf = /etc/ceph/ceph.conf rbd_store_user = {{ rbd_user }} rbd_store_pool = {{ rbd_pool }} -rbd_store_chunk_size = 8 {% endif -%} [image_format] diff --git a/templates/ocata/glance-api.conf b/templates/ocata/glance-api.conf index 28fb0135..17e64cb0 100644 --- a/templates/ocata/glance-api.conf +++ b/templates/ocata/glance-api.conf @@ -73,7 +73,6 @@ swift_store_create_container_on_put = true rbd_store_ceph_conf = /etc/ceph/ceph.conf rbd_store_user = {{ rbd_user }} rbd_store_pool = {{ rbd_pool }} -rbd_store_chunk_size = 8 {% endif -%} [image_format] diff --git a/templates/queens/glance-api.conf b/templates/queens/glance-api.conf index 790c12ad..3a3e6dc5 100644 --- a/templates/queens/glance-api.conf +++ b/templates/queens/glance-api.conf @@ -73,7 +73,6 @@ swift_store_create_container_on_put = true rbd_store_ceph_conf = /etc/ceph/ceph.conf rbd_store_user = {{ rbd_user }} rbd_store_pool = {{ rbd_pool }} -rbd_store_chunk_size = 8 {% endif -%} [image_format] diff --git a/templates/stein/glance-api.conf b/templates/stein/glance-api.conf index eb51d1f2..6b445c35 100644 --- a/templates/stein/glance-api.conf +++ b/templates/stein/glance-api.conf @@ -69,7 +69,6 @@ swift_store_create_container_on_put = true rbd_store_ceph_conf = /etc/ceph/ceph.conf rbd_store_user = {{ rbd_user }} rbd_store_pool = {{ rbd_pool }} -rbd_store_chunk_size = 8 {% endif -%} [image_format]