openstack/charm-ceph-fs
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Document rationale for erasure coded pools

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This addresses the questions:

- Why doesn't the charm let me use an erasure coded pool as the default?
- How do I use the secondary erasure coded pool once it is configured?

Change-Id: Ia885ce41043a4cb04a6d92993474c44e9b994c55
This commit is contained in:
Samuel Walladge 2023-10-17 08:29:49 +10:30
parent 4210d634e7
commit b852fa02bd
1 changed files with 10 additions and 0 deletions
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src/README.md
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@ -71,6 +71,14 @@ created: a replicated pool (for storing MDS metadata) and an erasure coded pool
`ceph-osd-replication-count` configuration option only applies to the metadata
(replicated) pool.
Note that the replicated pool will be the default pool for all data.
The user must manually configure the secondary erasure coded pool for use,
for example by using [file layouts][file-layouts].
It's not recommended to use an erasure coded data pool as the default data pool;
see [createfs docs][createfs] for more explanation.
Thus, the charm does not support this case.
Erasure coded pools can be configured via options whose names begin with the
`ec-` prefix.
@ -135,3 +143,5 @@ For general charm questions refer to the OpenStack [Charm Guide][cg].
[cloud-archive-ceph]: https://wiki.ubuntu.com/OpenStack/CloudArchive#Ceph_and_the_UCA
[cdg-ceph-erasure-coding]: https://docs.openstack.org/project-deploy-guide/charm-deployment-guide/latest/app-erasure-coding.html
[ceph-bluestore-compression]: https://docs.ceph.com/en/latest/rados/configuration/bluestore-config-ref/#inline-compression
[createfs]: https://docs.ceph.com/en/latest/cephfs/createfs/
[file-layouts]: https://docs.ceph.com/en/latest/cephfs/file-layouts/