Filestore Autoscaling Troubleshooting & Errors

Common Scale-Down Errors

"capacity for file share may only be increased"

• Trigger: Attempting to decrease the capacity of a BASIC_HDD or BASIC_SSD tier instance.
• Root Cause: Basic tier instances are backed by single Persistent Disks, which do not support shrinking.
• Resolution: Remind the user that Basic instances cannot be shrunk. You must delete and recreate, or migrate to a Zonal/Regional scale-out tier if elasticity is required.

"cannot decrease capacity below current usage"

• Trigger: Attempting to scale down a Zonal or Regional instance below the amount of data it currently holds.
• Root Cause: Self-evident safety mechanism; you cannot compress existing files mechanically by reducing provisioned space below used_bytes.
• Resolution: Set the target capacity strictly greater than the current used_bytes metric (with sufficient buffer).

Common Scale-Up Errors

RESOURCE_EXHAUSTED (Quota Limits)

• Trigger: Attempting to scale up an instance beyond available GCP project quotas in a region.
• Root Cause: The project lacks sufficient filestore.googleapis.com quota (e.g. CPUs, Storage Capacity).
• Resolution: Instruct the user to request a quota increase via the Pantheon Quotas page for the specific region and metric.

PERMISSION_DENIED

• Trigger: Missing IAM permissions.
• Root Cause: The executing service account or user lacks roles/file.editor or roles/file.admin.
• Resolution: Grant the necessary IAM bindings to the user executing the scaling operation.