Memory hook: Object key is not a disk path; retention is not a backup.
Must remember
Cloud Storage stores objects in buckets. Choose location for latency, resilience and data requirements; bucket names and object names are separate identifiers. Object storage is not a normal mutable block filesystem. Version/generation identifiers and preconditions support safe concurrent updates.
| Class | Remember |
|---|---|
| Standard | Frequent access; no minimum storage duration. |
| Nearline | Infrequent access; 30-day minimum storage duration. |
| Coldline | Rare access; 90-day minimum. |
| Archive | Very rare access; 365-day minimum. |
Lower storage price can be offset by retrieval, operations, transfer and early-deletion charges. Archive remains online object storage; do not import another vendor's restore-wait assumptions. Autoclass and lifecycle rules automate supported class/deletion behavior under different models; review compatibility and costs.
Uniform bucket-level access uses IAM rather than per-object ACLs. Public access prevention restricts public grants. Signed URLs provide time-bound access to a specific operation/object under the signing authority; treat the URL as a credential. Encryption is default, while customer-managed keys add key-control and availability responsibilities.
Versioning retains older generations under its model; soft delete supplies a recovery window; retention policies/holds prevent deletion under configured rules. A locked retention policy can be irreversible: understand it conceptually instead of experimenting on a disposable-cost assumption. Lifecycle deletion may be blocked by retention/holds.
Use gcloud storage for object operations, Storage Transfer Service for managed supported transfers and Transfer Appliance for suitable very large offline transfers. Check checksums, permissions, location compatibility and transfer progress. A successful upload is not a tested application restore.
Review details
Cloud Storage provides strong global consistency for object writes, overwrites, deletions and listing. Do not describe object listing as eventually consistent. Access-policy changes take time to propagate, and publicly cached objects can remain stale until their cache lifetime expires: those are different consistency boundaries.
A generation precondition can make a write conditional on the expected object version and prevent lost updates. Single-object operations are atomic, but a batch of several independent object requests is not a multi-object transaction. Pin a generation when a sequence of range reads must use the same version.
Choose under exam pressure
| Requirement | Choice and reason |
|---|---|
| Frequently accessed application objects | Standard storage in an appropriate location. |
| Restrict access consistently | Uniform bucket-level access and least-privilege IAM. |
| Bulk recurring transfer | Storage Transfer Service where the source/destination are supported. |
Traps
- Cheap storage classes can incur minimum-duration and retrieval charges.
- A signed URL can be used by whoever possesses it until its conditions expire.
Active recall
1. Minimum duration for Archive?
365 days, with relevant early-deletion economics.
2. Does Archive require an offline retrieval job like some other services?
No. Google Cloud Storage Archive is online object storage.
3. What does uniform bucket-level access remove?
The separate per-object ACL authorization model.
4. Why can a lifecycle deletion fail?
A retention policy or hold can prohibit deletion.
5. Why protect a signed URL?
It conveys access authority to its holder for the defined request and period.