ceph-performance SKILL.md skillA
ceph-performance from air-gapped/skills is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.
mdr add air-gapped/skills/ceph-performance@git:20261027.28d2580Pins git:20261027.28d2580 in mdr.lock. Pin the fingerprint instead.
- Audit grade
- A, 17 of 17 checks passed
- Kind
- SKILL.md skill
- Repository
- air-gapped/skills
- Path
.claude/skills/ceph-performance/SKILL.md- Versions recorded
- 8
- Latest version
- git:20261027.28d2580, committed Oct 27, 2026
- First version recorded
- Sep 22, 2026
- Size
- 8,572 bytes
- Repository stars
- 6
- License
- MIT
Tune and benchmark a healthy Ceph cluster, with Rook-on-Kubernetes specifics: mClock profiles and the NVMe capacity-fallback trap (osd_mclock_max_capacity_iops), osd_memory_target from pod requests, BlueStore allocation and cache defaults, PG autoscaler targets (mon_target_pg_per_osd, bulk, target_size_ratio), public/cluster network and Multus choices, msgr2 modes, Tentacle Fast EC (allow_ec_optimizations, stripe_unit), krbd vs rbd-nbd in ceph-csi, librbd cache, and benchmark method…
Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.
What the file says
# ceph-performance
Defaults below hold at Ceph v19.2.7 and v20.2.4
(`src/common/options/*.yaml.in`) and Rook v1.21.1; sources in
`references/sources.md`.
Measure before and after every change; `ceph config show osd.N <opt>` is
the value actually in force.
## mClock: the NVMe capacity trap
mClock sizes every reservation from each OSD's measured IOPS capacity. At
OSD start an `osd bench` sets `osd_mclock_max_capacity_iops_{hdd,ssd}`.
If the result exceeds the sanity threshold — **500 (HDD), 80 000 (SSD)** —
it is discarded and the OSD falls back to the default capacity
(**21 500** SSD) with a cluster-log warning. Modern NVMe routinely exceeds
80 000, so mClock under-drives it.
1. `ceph config show osd.N osd_mclock_max_capacity_iops_ssd` on every OSD;
`21500` means the fallback hit.
2. Measure the device with fio at 4 KiB random write, then
`ceph config set osd.N osd_mclock_max_capacity_iops_ssd <iops>`.
3. Re-check after replacing a device — the value is per OSD.
Profiles: `balanced` is the default from 17.2.7 and in Reef, Squid and
Tentacle (17.2.0–17.2.6 shipped `high_client_ops`). Use `high_client_ops`
for latency-sensitive steady state, `high_recovery_ops` only for a
…Read the whole file at its exact version.
How to install
mdr add air-gapped/skills/ceph-performance@sha256:89661a10a0b3bc4bThe line at the top of this page pins the label git:20261027.28d2580, which is what most people want. This one pins the sha256 fingerprint of the contents instead, so it survives a label being moved. Either way the exact version is written to mdr.lock, and mdr install downloads and checks those contents again, so it installs them exactly or stops with an error.
[](https://markdownregistry.com/a/art_tjbucx6gfh65mnbz)
7 badge image fetches in 30 days. What the badge shows.
Versions
The registry has recorded 8 versions of this file, between Sep 22, 2026 and Oct 27, 2026, about one every 5 days.
| version | committed | commit | size | audit | |
|---|---|---|---|---|---|
| git:20261027.28d2580 latest | 2026-10-27 | 28d2580 | 8,572 B | A | view · diff |
| git:20261027.fa5aa16 | 2026-10-27 | fa5aa16 | 8,221 B | A | view · diff |
| git:20261027.2d4547a | 2026-10-27 | 2d4547a | 7,987 B | A | view · diff |
| git:20261027.9c1ec9d | 2026-10-27 | 9c1ec9d | 8,002 B | A | view · diff |
| git:20261027.a664066 | 2026-10-27 | a664066 | 7,816 B | A | view · diff |
| git:20260922.6f1744d | 2026-09-22 | 6f1744d | 6,943 B | A | view · diff |
| git:20260922.1fe1a44 | 2026-09-22 | 1fe1a44 | 7,274 B | A | view · diff |
| git:20260922.2273c5a | 2026-09-22 | 2273c5a | 7,192 B | A | view |
Audit of the latest version
- pass: Frontmatter block present
- pass: Frontmatter declares a name
- pass: Frontmatter declares a description
- pass: Size between 200 bytes and 200 KB (8572 bytes)
- pass: No zero-width or bidi control characters
- pass: No instruction hidden inside an HTML comment
- pass: No link to an exfiltration or paste host
- pass: No credential-shaped string
- pass: No instruction to send local credentials anywhere
- pass: No text hidden with inline styles
- pass: No prompt-injection phrasing
- pass: No curl or wget piped into a shell
- pass: No recursive delete of root, home or parent
- pass: No instruction to read or print local credentials
- pass: No base64 blob over 200 characters
- pass: No link to a raw IP address
- pass: No script tag
Source
air-gapped/skills · 6 stars · license MIT · pushed 2026-11-04 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_tjbucx6gfh65mnbz GET https://markdownregistry.com/api/v1/resolve?ref=air-gapped/skills/ceph-performance GET https://markdownregistry.com/api/v1/blob/89661a10a0b3bc4b1453789505fe0814bc16a4294f4ae76ec8b23da7d62f00ae
Your AI assistant does the legwork. You hear about the deals worth your word. Hand yours the standing instructions at modelranch.com and it joins the network that reads files like this one.
Guides: the SKILL.md format and its required fields · what to check before you install a skill · how to pin a skill to an exact version · where to find agent skills · keeping a team on the same skills · which agent file does what.