doc: add architecture information to ceph.md#12
doc: add architecture information to ceph.md#12senolcolak merged 1 commit intocobaltcore-dev:mainfrom
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Add information about the architecture of a Ceph cluster to ceph.md. Signed-off-by: Zac Dover <zac.dover@proton.me>
📝 WalkthroughWalkthroughAdded a comprehensive "Architecture" subsection to Ceph documentation detailing storage cluster internals, including daemon roles, CRUSH-based data placement, RADOS object storage, monitor consensus, cephx authentication, cluster management, and client interfaces. Changes
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Actionable comments posted: 2
🧹 Nitpick comments (1)
docs/architecture/ceph.md (1)
62-70: Consider restructuring the cluster-map paragraph into bullets.The map breakdown is accurate but very dense in one sentence chain. Converting each map type into bullets will improve scanability and reduce maintenance friction.
🤖 Prompt for AI Agents
Verify each finding against the current code and only fix it if needed. In `@docs/architecture/ceph.md` around lines 62 - 70, Split the dense "Cluster Map" paragraph into a bulleted list that creates one bullet per map type (Monitor Map, OSD Map, PG Map, CRUSH Map, MDS Map) and a short lead sentence; for each bullet include the key fields currently described (e.g., Monitor Map: cluster fsid, monitor positions, names, addresses, ports; OSD Map: cluster fsid, pool lists, replica sizes, PG numbers, OSD statuses; PG Map: PG versions, timestamps, placement group details; CRUSH Map: storage devices, failure domain hierarchy, traversal rules; MDS Map: MDS map epoch, metadata storage pool, metadata server info) and preserve the final sentence about operational state history and Ceph Monitors maintaining master copies. Ensure wording remains concise and preserves existing terms "Cluster Map", "Monitor Map", "OSD Map", "PG Map", "CRUSH Map", and "MDS Map".
🤖 Prompt for all review comments with AI agents
Verify each finding against the current code and only fix it if needed.
Inline comments:
In `@docs/architecture/ceph.md`:
- Around line 49-53: The wording claiming "clients interact directly with Ceph
OSDs" is too broad; update the sentence that describes direct client↔OSD
interaction to specify it applies to RADOS/librados clients (e.g.,
"RADOS/librados paths allow direct client-to-OSD interactions"), and add a
clarifying clause that higher-level services like CephFS and RGW instead involve
MDS and RGW components respectively, so they do not follow the direct OSD path.
- Around line 136-137: Update the inaccurate phrase "mountable as kernel
objects" in the CephFS description: replace that wording so it states CephFS is
typically mounted via the kernel client or via FUSE (e.g., change the sentence
containing "mountable as kernel objects or FUSE" to use "mounted via the kernel
client or via FUSE" and keep the surrounding context about librados providing
direct parallel cluster access).
---
Nitpick comments:
In `@docs/architecture/ceph.md`:
- Around line 62-70: Split the dense "Cluster Map" paragraph into a bulleted
list that creates one bullet per map type (Monitor Map, OSD Map, PG Map, CRUSH
Map, MDS Map) and a short lead sentence; for each bullet include the key fields
currently described (e.g., Monitor Map: cluster fsid, monitor positions, names,
addresses, ports; OSD Map: cluster fsid, pool lists, replica sizes, PG numbers,
OSD statuses; PG Map: PG versions, timestamps, placement group details; CRUSH
Map: storage devices, failure domain hierarchy, traversal rules; MDS Map: MDS
map epoch, metadata storage pool, metadata server info) and preserve the final
sentence about operational state history and Ceph Monitors maintaining master
copies. Ensure wording remains concise and preserves existing terms "Cluster
Map", "Monitor Map", "OSD Map", "PG Map", "CRUSH Map", and "MDS Map".
| Traditional architectures rely on centralized components—gateways, brokers, or | ||
| APIs—that act as single points of entry, creating failure points and | ||
| performance limits. Ceph eliminates these centralized components, enabling | ||
| clients to interact directly with Ceph OSDs. OSDs create object replicas on | ||
| other nodes to ensure data safety and high availability, while monitor clusters |
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Clarify direct client↔OSD behavior scope.
The statement on Line 51-Line 53 is too broad. Direct client-to-OSD applies to RADOS/librados paths, but CephFS and RGW involve MDS/RGW components. Please narrow the wording to avoid architectural confusion.
Suggested wording update
-Traditional architectures rely on centralized components—gateways, brokers, or
-APIs—that act as single points of entry, creating failure points and
-performance limits. Ceph eliminates these centralized components, enabling
-clients to interact directly with Ceph OSDs.
+Traditional architectures often rely on centralized components—gateways,
+brokers, or APIs—that can become failure points and performance limits.
+In Ceph’s RADOS data path, clients can interact directly with OSDs based on
+CRUSH-derived placement, avoiding a centralized lookup bottleneck.📝 Committable suggestion
‼️ IMPORTANT
Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.
| Traditional architectures rely on centralized components—gateways, brokers, or | |
| APIs—that act as single points of entry, creating failure points and | |
| performance limits. Ceph eliminates these centralized components, enabling | |
| clients to interact directly with Ceph OSDs. OSDs create object replicas on | |
| other nodes to ensure data safety and high availability, while monitor clusters | |
| Traditional architectures often rely on centralized components—gateways, | |
| brokers, or APIs—that can become failure points and performance limits. | |
| In Ceph's RADOS data path, clients can interact directly with OSDs based on | |
| CRUSH-derived placement, avoiding a centralized lookup bottleneck. | |
| OSDs create object replicas on | |
| other nodes to ensure data safety and high availability, while monitor clusters |
🤖 Prompt for AI Agents
Verify each finding against the current code and only fix it if needed.
In `@docs/architecture/ceph.md` around lines 49 - 53, The wording claiming
"clients interact directly with Ceph OSDs" is too broad; update the sentence
that describes direct client↔OSD interaction to specify it applies to
RADOS/librados clients (e.g., "RADOS/librados paths allow direct client-to-OSD
interactions"), and add a clarifying clause that higher-level services like
CephFS and RGW instead involve MDS and RGW components respectively, so they do
not follow the direct OSD path.
| mountable as kernel objects or FUSE. Modern applications access storage through | ||
| librados, which provides direct parallel cluster access supporting pool |
There was a problem hiding this comment.
Fix CephFS mount terminology.
“mountable as kernel objects” on Line 136 is inaccurate phrasing. CephFS is typically mounted via the kernel client or via FUSE.
Suggested wording update
-Amazon S3 and OpenStack Swift; and CephFS provides POSIX-compliant filesystems
-mountable as kernel objects or FUSE.
+Amazon S3 and OpenStack Swift; and CephFS provides POSIX-compliant filesystems
+that can be mounted via the kernel client or via FUSE.🤖 Prompt for AI Agents
Verify each finding against the current code and only fix it if needed.
In `@docs/architecture/ceph.md` around lines 136 - 137, Update the inaccurate
phrase "mountable as kernel objects" in the CephFS description: replace that
wording so it states CephFS is typically mounted via the kernel client or via
FUSE (e.g., change the sentence containing "mountable as kernel objects or FUSE"
to use "mounted via the kernel client or via FUSE" and keep the surrounding
context about librados providing direct parallel cluster access).
senolcolak
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senolcolak
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The explanation is correct and nice for the fundamental parts of Ceph. I think this definition should also include the RBD RGW, Optional(CephFS) parts as well.
I can add sections that explain what RBD is, what RGW is, and what CephFS is, and I can add tutorial sections that explain how to set them up in a Ceph cluster. That shouldn't take more than a couple of working days (all the information is already on docs.ceph.com and was compiled in 2023). But this will come with an ongoing documentation maintenance cost in order to avoid technical debt. Are we cool with that? |
Your point about maintenance cost is valid for tutorials, but that is not what I meant. We only need a complete Ceph definition, including brief definitions of RBD, RGW, and maybe CephFS. No setup sections are necessary. |
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Add information about the architecture of a Ceph cluster to ceph.md.
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