croit OS Images

croit nodes run an immutable OS image that croit builds, tests, and serves. The image comes in two variants, Core and Enhanced, that differ only in the Ceph build they ship. You choose a variant during first-time setup and can change it later under Servers → Images → Change Ceph Variant.

Core

The Core image runs upstream Ceph. croit builds and tests each release and applies critical patches, but the Ceph code remains the upstream code. Core is the default and does not require a license.

Enhanced

The Enhanced image runs croit's own Ceph build, which adds features that croit develops in-house and that upstream Ceph does not provide:

• CephFS MDS notifications (UDP & Kafka): The metadata server emits notifications about filesystem events, which you can receive over UDP or Kafka. Learn more.
• CephFS Guard: Additional protection for CephFS. Learn more.
• Improved CephFS mirroring: Run CephFS mirroring with faster, more controllable replication and safer metadata maintenance. Our mirroring combines efficient snapdiff-based synchronization through low-level libcephfs APIs with runtime-tunable parallel workers, multi-filesystem balancing, interruption-aware recovery, and detailed metrics. Production-driven bug fixes across libcephfs and ceph-mds improve snapdiff correctness and end-to-end reliability.
• Improved MDS scrubbing: Enhanced MDS scrubbing reduces cache pressure, handles damaged directory objects gracefully, reports live progress, and simplifies post-repair cleanup. Without the enhanced-scrub patches, scrubbing a file system of production-grade size may need a terabyte of memory or even more; with our patches you will not notice the extra memory requirement.

croit's Ceph build stays open source and compatible with upstream Ceph, so you can switch a cluster back to Core at any time without migrating or moving data. Because Enhanced uses croit's build, it requires an active license; Core does not.