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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
configuring scrubbing.
#. **Replication:** Like Ceph Clients, Ceph OSD Daemons use the CRUSH
algorithm, but the Ceph OSD Daemon uses it to compute where replicas of
objects should be stored (and for rebalancing). In a typical write scenario,
a client uses the CRUSH algorithm to compute where to store an object, maps
the object to a pool and placement group, then looks at the CRUSH map to
identify the primary OSD for the placement group.
The client writes the object to the identified placement group in the
primary OSD. Then, the primary OSD with its own copy of the CRUSH map
identifies the secondary and tertiary OSDs for replication purposes, and
replicates the object to the appropriate placement groups in the secondary
and tertiary OSDs (as many OSDs as additional replicas), and responds to the
client once it has confirmed the object was stored successfully.
#. **Replication:** Data replication involves a collaboration between Ceph
Clients and Ceph OSD Daemons. Ceph OSD Daemons use the CRUSH algorithm to
determine the storage location of object replicas. Ceph clients use the
CRUSH algorithm to determine the storage location of an object, then the
object is mapped to a pool and to a placement group, and then the client
consults the CRUSH map to identify the placement group's primary OSD.
After identifying the target placement group, the client writes the object
to the identified placement group's primary OSD. The primary OSD then
consults its own copy of the CRUSH map to identify secondary and tertiary
OSDS, replicates the object to the placement groups in those secondary and
tertiary OSDs, confirms that the object was stored successfully in the
secondary and tertiary OSDs, and reports to the client that the object
was stored successfully.
.. ditaa::
@ -469,9 +470,8 @@ the greater cluster provides several benefits:
| | | |
+---------------+ +---------------+
With the ability to perform data replication, Ceph OSD Daemons relieve Ceph
clients from that duty, while ensuring high data availability and data safety.
By performing this act of data replication, Ceph OSD Daemons relieve Ceph
clients of the burden of replicating data.
Dynamic Cluster Management
--------------------------