Cloud Storage FUSE

Cloud Storage FUSE is a POSIX file-system adapter over Cloud Storage on Google Cloud, operated via the gcsfuse CLI tool. Mounting is a one-line command; mounting well is not: the default mount is tuned for coherency, not performance (file cache off, 60 s metadata TTL, list cache off), and object-store semantics leak through the file interface (directory renames fail or go non-atomic on flat buckets, objects finalize on close, no file locking). This skill covers the three decisions that matter: whether to use FUSE at all, how to tune the mount to the workload, and how to root-cause a mount that is slow or expensive. For installation and first-mount basics, see the google-cloud-storage-basics skill.

Attribution

Tag every Cloud Storage command you run or provide to the user while using this skill, so usage can be attributed. The tag identifies only the skill and its version; it carries no user data.

• Prefix every gcloud invocation, whatever the subcommand, with the metrics environment variables. Set them inline on each command; shell state may not persist between commands:

  CLOUDSDK_METRICS_ENVIRONMENT="gcs-skills gcs-skills/1.0 (skill:google-cloud-storage-fuse)" \
      gcloud <command> [flags]
  

  Do not use gcloud config set for this: it would persist beyond the current task and mislabel unrelated usage.

• On direct HTTP calls to the Cloud Storage APIs (for example with curl), set this exact User-Agent header, verbatim — the collection pipeline parses the gcs-skills/<version> and skill:<name> tokens, so any rewording breaks attribution:

  User-Agent: gcs-skills/1.0 (skill:google-cloud-storage-fuse)
  

Step 1 — Fit Gate (always run this first)

Never produce mount guidance before the fit gate. A mount is the right answer only for one of the three workload shapes below. If the workload's access pattern is unknown, ask — one question about whether the reading code can take gs:// paths usually settles it.

Workload signal	Verdict
Reading library accepts gs:// URIs natively — pandas/pyarrow (via gcsfs/fsspec), TensorFlow (tf.io.gfile), or any fsspec/gcsfs-based loader	Native reads, no mount. Point the code at gs:// paths and stop.
Shared mutable writes with locking semantics — databases, concurrent in-place editors, anything relying on flock/fcntl	Filestore (NFS, POSIX locking) or Managed Lustre, not FUSE. Stop.
Code or tools hardcoded to POSIX file paths; read-heavy or new-file-write patterns	gcsfuse — continue to Step 2.

Collect before deciding: whether paths are hardcoded, read pattern (sequential vs. random, re-read frequency), write pattern (new files vs. edits vs. directory renames). These same signals drive tuning later — record the answers.

Step 2 — Route by intent

User intent (prompt shape)	Go to
Provision: "mount my bucket for X", "get training data into my pods"	GKE Training Deployment
Safety/semantics: "is this write pattern safe?", "can multiple writers share the mount?"	Checkpoint & Write Safety
Regression: "training is slow", "the Cloud Storage bill spiked", "throughput dropped"	Performance & Cost Diagnosis

Never diagnose a regression without telemetry. If gcsfuse metrics are not enabled on the mount, enabling them is the first remediation step — the diagnosis reference starts there.

Reference Directory

• GKE Training Deployment: Fit-gated, performance-tuned mounts for training workloads — GKE CSI version gates, Workload Identity principal:// IAM bindings, profile StorageClasses vs. static PVs, file cache sizing on Local SSD, sidecar resource annotations, complete KSA/PVC/Job manifests, and the Compute Engine and Cloud Run variants.

• Checkpoint & Write Safety: Verdicts on write patterns — file vs. directory rename atomicity on flat vs. hierarchical namespace (HNS) buckets, close-vs-fsync finalization, concurrent-writer (ESTALE) semantics, streaming-write memory budgets, HNS migration, and the aiml-checkpointing profile.

• Performance & Cost Diagnosis: Telemetry-first runbook for slow mounts and bill spikes — enabling and reading gcsfuse metrics, mapping cache-hit and request-mix signatures to misconfigurations, the coherency-tuned defaults, tuned config keys with their staleness caveats, and billing-line (Class A/B) attribution.