--- name: google-cloud-storage-fuse description: >- Mounts Cloud Storage buckets as a POSIX file system with Cloud Storage FUSE (gcsfuse). Use when you need to interact with gcsfuse — decide whether FUSE, native gs:// reads, or Filestore/Managed Lustre fits a workload, deploy tuned mounts on GKE, Compute Engine, or Cloud Run, enable and size the file, stat, and list caches, tune mount flags or config-file settings, apply workload profiles, keep ML checkpointing safe (rename atomicity, hierarchical namespace, close-time finalization, concurrent writers), or diagnose slow training, low throughput, or Cloud Storage bill spikes on existing mounts with gcsfuse metrics. Covers mount semantics, the gcsfuse CLI and config file, the GKE gcsfuse CSI driver (Workload Identity principal:// bindings, profile StorageClasses, sidecar sizing), and Cloud Run volume mounts. Don't use for bucket administration or data management without a mount (use the google-cloud-storage-basics skill instead) or for fully POSIX-compliant shared file systems (use Filestore or Managed Lustre). license: Apache-2.0 metadata: version: v1 publisher: google tags: - gcs - gcsfuse - fuse - mount - file-system category: Storage support_tier: primary --- # Google Cloud Storage FUSE Cloud Storage FUSE (gcsfuse) is a POSIX file-system adapter over Cloud Storage's immutable object store. 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: ```bash CLOUDSDK_METRICS_ENVIRONMENT="gcs-skills gcs-skills/1.0 (skill:google-cloud-storage-fuse)" \ gcloud [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/` and `skill:` 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](references/gke-training-deployment.md) Safety/semantics: "is this write pattern safe?", "can multiple writers share the mount?" | [Checkpoint & Write Safety](references/checkpoint-safety.md) Regression: "training is slow", "the Cloud Storage bill spiked", "throughput dropped" | [Performance & Cost Diagnosis](references/performance-diagnosis.md) **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](references/gke-training-deployment.md): 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](references/checkpoint-safety.md): 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](references/performance-diagnosis.md): 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.