Commit Graph
2 Commits
Author SHA1 Message Date
Ilker ManapandClaude Opus 5 753f4e3265 Let a node say how much room it has left
CI / test (push) Failing after 1m31s
Disk was the one resource nothing reported. `statfs` was already being called
on every model directory, but only to ask whether the filesystem was a network
one — the free space it returns in the same struct was thrown away. So the
only way to find out why a node was filling up was to ssh to it, which is what
this system exists to avoid.

Reported per filesystem rather than per configured directory. Free space
belongs to the disk, not the path: two model directories on one disk are one
pool of bytes, and counting them separately would let the control plane add
24 GB to 24 GB and place a 40 GB model on a node that has 24.

Shared filesystems are summed separately from local ones and left out of a
node's own total. Space on a filer belongs to everyone mounting it, so twenty
nodes would otherwise each report the same free terabyte, and a scheduler
would place twenty models into room for one.

Nothing reported means nothing is known, everywhere: an agent too old to send
storage and a node with no model directories both send nothing, and both must
read as unknown rather than as a full disk. `ctl nodes` and the dashboard show
a dash, the metric is absent rather than zero, and a missing directory — which
is what an unmounted filer looks like — is skipped rather than reported as
having no space.

Shown as free out of total, because the first is useless without the second:
8 GB free is comfortable on a 10 TB filer and nearly full on a 10 GB root
partition, and only the second stops a model being placed.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-09-18 09:38:57 +02:00
ilkerandClaude Opus 5 06672d1b85 Phase 3 (1/3): cluster inventory and placement
CI / test (push) Successful in 23s
The two hard constraints from plan §1.1 are enforced structurally rather than
checked after the fact: there is no code path that can combine nodes from two
fabrics, and only GPUs of the profile's class are ever considered. Getting
either wrong produces a replica that starts, passes health checks, and then
hangs or crawls under load — which looks like success until traffic arrives.

- inventory: nodes, hardware, fabric attachments, allocations. A re-registering
  agent cannot clear an operator's cordon, since a cordon is usually in place
  because something is wrong with the node. A GPU with an ECC fault or another
  process on it is not free in any useful sense. Replicas are released whole,
  because they fail whole.
- placement: highest-priority profile that fits, with every rejected candidate
  explained. "Unschedulable" on its own tells an operator nothing about which
  of six constraints bit.
- bin packing fills partly used nodes first so whole nodes stay free for large
  models that cannot be split; multi-node replicas get the emptiest machines
  instead, being the least movable thing in the cluster.
- NVLink-aware GPU selection keeps a tensor-parallel group inside one domain
  where the topology is known, falling back to lowest free indices otherwise.

Property-based tests generate 400 random clusters and assert the invariants on
every placement produced: one fabric per multi-node replica, only that fabric's
HCAs per shard, one GPU class, no unhealthy or already-allocated GPU. The
table-driven tests cover the cases someone thought of; these cover the rest.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-09-16 02:07:29 +02:00