## Why
Ceph OSDs manage their own I/O ordering, so the kernel scheduler on the backing disks just adds overhead. The original intent was to set those disks to the `noop` scheduler. The whole OSD fleet (k8s + incus nodes) runs AlmaLinux 9 on blk-mq kernels (5.14), where the equivalent of `noop` is `none`.
## Changes
- Add `profiles::ceph::osd_scheduler`, rendering a udev rule from the `ceph_osd_devices` fact (PR #504) that pins `queue/scheduler` to `none` on each OSD disk.
- Reload udev and trigger the matched block devices so the setting applies immediately; the udev rule keeps it set across reboots and device re-add.
- No-op when the fact is absent/empty, so VMs and non-OSD hosts are untouched.
- Include the class from `profiles::ceph::osd` so it lands only on OSD hosts.
https://claude.ai/code/session_01JUoARVdmhxKQHyyyp1pxeT
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Co-authored-by: BenVincent <benvin@main.unkin.net>
Reviewed-on: #505
Co-authored-by: Ben Vincent <ben@unkin.net>
Co-committed-by: Ben Vincent <ben@unkin.net>
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