Ceph » Orchestrator

By default, cephadm uses '/usr/lib/sysctl.d/' (→ cephadm:L65) as default path for the osd-specific sysctl settings.

According to the Filesystem Hierarchy Standard /usr is the second major section of the filesystem. /usr is shareable, read-only data. That means that /usr should be shareable between various FHS-compliant hosts and must not be written to. (→ FHS 3.0 Sec. 4.1)

I would recommend that '/etc/sysctl.d' is used instead, because that would be a proper place for host specific, non-distribution sysctl configuration files.

Uncompliance with that specific FHS rule may break technologies that rely on '/usr/lib/sysctl.d/' being either read-only or completely overwritten (an example would be SUSE's transactional-update).

Backporting
Regarding backporting there would be several different strategies:

1. Leave ceph sysctl configuration at '/usr/lib/sysctl.d'
   PRO: No changes to stable branches
   CON: Older branches stay uncompliant/ unusable with certain technologies.
2. Use '/etc/sysctl.d/' if '/usr/lib/sysctl.d/' is unwritable as root (→ read-only)
   PRO: No changes to already set up systems.
   PRO: Will be useable with read-only filesystem.
   CON: Not working if '/usr/lib/sysctl.d/' is overwritten by the distribution
3. Migrate configuration from '/usr/lib/sysctl.d' to '/etc/sysctl.d'
   PRO: Full FHS compliance; read-only and overwrite scenarios supported.
   CON: Changes on already set up systems.

Related

• http://saka.docsio.net/69072256/cephadm-sysctl-dir-parameter-does-not-affect-location-of-usr-lib-sysctl-d-90-ce
• https://tracker.ceph.com/issues/52481