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Storage nodes not balanced (r6,dsR6)

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Draft of new section on optimization with a large number of OSDs.
Fixed typo.
Partially address patchset 1 review comments. One open question outstanding.

Signed-off-by: Ron Stone <ronald.stone@windriver.com>
Change-Id: I9f44857e49dc1e289301d496611e508a338048e2
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Ron Stone 2022-05-18 11:27:10 -04:00
parent 3d1f1c2b2f
commit 5265340f9e
2 changed files with 52 additions and 0 deletions
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1
doc/source/storage/kubernetes/index-storage-kub-e797132c87a8.rst
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@ -123,6 +123,7 @@ Configure Ceph OSDs on a Host
add-a-storage-tier-using-the-cli
provision-storage-on-a-controller-or-storage-host-using-horizon
provision-storage-on-a-storage-host-using-the-cli
optimization-with-a-large-number-of-osds-df2169096946
replace-osds-and-journal-disks
replace-osds-on-a-standard-system-f3b1e376304c
replace-osds-on-an-aio-dx-system-319b0bc2f7e6

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doc/source/storage/kubernetes/optimization-with-a-large-number-of-osds-df2169096946.rst Normal file
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.. _optimization-with-a-large-number-of-osds-df2169096946:
========================================
Optimization with a Large number of OSDs
========================================
You may need to optimize your Ceph configuration for balanced operation across
deployments with a high number of |OSDs|.
.. rubric:: |context|
As the number of |OSDs| increases, choosing the correct <pg_num> and <pgp_num>
values becomes more important as they have a significant influence on the
behavior of the cluster and the durability of the data should a catastrophic
event occur.
|org| recommends the following values:
* Fewer than 5 |OSDs|: Set <pg_num> and <pgp_num> to 128.
* Between 5 and 10 |OSDs|: Set <pg_num> and <pgp_num> to 512.
* Between 10 and 50 |OSDs|: Set <pg_num> and <pgp_num> to 4096.
* More than 50 |OSDs|: Understanding the memory, CPU and network usage
tradeoffs, calculate and set the optimal <pg_num> and <pgp_num> values for
your scenario.
Use the equation below and round up to a number power of 2.
*Total PGs = (OSDs * 100) / <pool_size>*
<pool_size> is either the number of replicas for replicated pools or the K+M
sum for erasure coded pools as returned by ``ceph osd erasure-code-profile
get <profile>``, where <profile> is usually default.
For more information on the tradeoffs involved, consult the Ceph
documentation at:
https://docs.ceph.com/en/latest/rados/operations/placement-groups/
.. rubric:: |eg|
* For a deployment with 7 |OSDs|, use the following commands to set <pg> and
<pgp_num> to 512.
.. code-block:: none
$ ceph osd pool set kube-rbd pg_num 512
$ ceph osd pool set kube-rbd pgp_num 512