Bucket Quotas

Best-effort enforcement
Bucket quota enforcement is best-effort and not real-time. MinIO AIStor evaluates quota usage periodically through its internal scanner, so a bucket may temporarily exceed its configured quota between scanner cycles. Bucket hard-quota enforcement is wired only into the S3 API request handlers, Internal processes like Inventory will not go through quota enforcement. Do not rely on bucket quotas as a hard ceiling for safety-critical storage limits.

MinIO AIStor supports setting hard quotas on buckets to limit the total amount of data a bucket can store. When a bucket reaches its configured quota, MinIO AIStor rejects further write operations to that bucket until data is removed to bring usage below the limit.

Bucket quotas are not available when MinIO AIStor runs in S3 Express One Zone mode.

Buckets that accept a quota

Any user bucket accepts a quota, including an AIStor Tables warehouse bucket. A warehouse’s client writes pass through the same S3 quota check as any other bucket.

MinIO AIStor rejects a quota on a reserved internal bucket, because writes to those buckets do not pass through the check and the limit could not be enforced. Setting a size of 0 on such a bucket removes any quota configuration left on it.

Set a hard quota

Use mc quota set to set a hard quota on a bucket. The --size flag specifies the maximum storage size for the bucket.

mc quota set ALIAS/BUCKET --size SIZE

Replace SIZE with a value and unit suffix, for example 1GB, 10GB, or 500MB.

The following example sets a 1 GB hard quota on the mybucket bucket:

mc quota set myminio/mybucket --size 1GB

When the total size of objects in the bucket reaches the quota, MinIO AIStor returns an error for any further PUT operations.

Verify the quota

To view the current quota configuration for a bucket:

mc quota info ALIAS/BUCKET

Clear a quota

To remove the quota from a bucket:

mc quota clear ALIAS/BUCKET

Required permissions

The user or service account performing quota operations must have the following admin permissions:

Permission Description
admin:SetBucketQuota Allows setting or clearing a bucket quota.
admin:GetBucketQuota Allows retrieving the current bucket quota.

The built-in consoleAdmin policy includes both of these permissions.

Monitoring

MinIO AIStor exposes bucket quota metrics for integration with Prometheus or other monitoring systems:

  • v3 metric: minio_cluster_usage_buckets_quota_total_bytes (labels: bucket)
  • v2 metric: minio_bucket_quota_total_bytes (labels: bucket, server)

See Metrics and Alerts for more information on configuring monitoring.