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doc/architecture: edit "Replication"

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Edit "Replication" in the "Smart Daemons Enable Hyperscale" section of
doc/architecture.rst.

Signed-off-by: Zac Dover <zac.dover@proton.me>
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Zac Dover 2023-09-29 07:37:40 +10:00
parent 6d8679ebcd
commit 4cf22e195a
1 changed files with 16 additions and 16 deletions
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doc/architecture.rst
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@ -430,19 +430,20 @@ the greater cluster provides several benefits:
weren't apparent in a light scrub. See `Data Scrubbing`_ for details on weren't apparent in a light scrub. See `Data Scrubbing`_ for details on
configuring scrubbing. configuring scrubbing.
#. **Replication:** Like Ceph Clients, Ceph OSD Daemons use the CRUSH #. **Replication:** Data replication involves a collaboration between Ceph
algorithm, but the Ceph OSD Daemon uses it to compute where replicas of Clients and Ceph OSD Daemons. Ceph OSD Daemons use the CRUSH algorithm to
objects should be stored (and for rebalancing). In a typical write scenario, determine the storage location of object replicas. Ceph clients use the
a client uses the CRUSH algorithm to compute where to store an object, maps CRUSH algorithm to determine the storage location of an object, then the
the object to a pool and placement group, then looks at the CRUSH map to object is mapped to a pool and to a placement group, and then the client
identify the primary OSD for the placement group. consults the CRUSH map to identify the placement group's primary OSD.
The client writes the object to the identified placement group in the After identifying the target placement group, the client writes the object
primary OSD. Then, the primary OSD with its own copy of the CRUSH map to the identified placement group's primary OSD. The primary OSD then
identifies the secondary and tertiary OSDs for replication purposes, and consults its own copy of the CRUSH map to identify secondary and tertiary
replicates the object to the appropriate placement groups in the secondary OSDS, replicates the object to the placement groups in those secondary and
and tertiary OSDs (as many OSDs as additional replicas), and responds to the tertiary OSDs, confirms that the object was stored successfully in the
client once it has confirmed the object was stored successfully. secondary and tertiary OSDs, and reports to the client that the object
was stored successfully.
.. ditaa:: .. ditaa::
@ -469,9 +470,8 @@ the greater cluster provides several benefits:
| | | | | | | |
+---------------+ +---------------+ +---------------+ +---------------+
With the ability to perform data replication, Ceph OSD Daemons relieve Ceph By performing this act of data replication, Ceph OSD Daemons relieve Ceph
clients from that duty, while ensuring high data availability and data safety. clients of the burden of replicating data.
Dynamic Cluster Management Dynamic Cluster Management
-------------------------- --------------------------