Storage
Domain 4 covers NHN Cloud storage options: Block Storage, Object Storage, NAS, and Archive Storage. The exam tests matching workload requirements to storage behavior and durability.
Core rules
- Block Storage is a virtual disk attached to an instance. It is formatted by the guest OS and is suitable for databases, logs, and boot volumes. It is tied to an Availability Zone and must be detached before moving between instances.
- Object Storage stores objects in containers with a key. It is accessed over HTTP APIs, not mounted as a local disk. Use it for static assets, backups, and unstructured data. Container policies control public read and lifecycle.
- NAS provides shared file storage over a network protocol to multiple instances. Use it when several nodes need the same files; do not use block storage for shared writes.
- Archive Storage is for long-term retention with low access frequency. Retrieval and minimum storage duration can affect cost, so it is not a primary database disk.
- Snapshots and replication protect data, but they are not a substitute for application-consistent backups. Check retention and restore procedures.
Worked example
A website serves product images to anonymous users and stores nightly backups. Put images in an Object Storage container with public read policy and a CDN in front. Put backups in a separate private container with lifecycle deletion after 90 days. Reason: object storage scales for static content; public read is scoped to the image container; lifecycle enforces retention without manual cleanup.
Traps
Do not mount Object Storage as a block device. Do not use Archive Storage for low-latency reads. Do not assume a block volume follows an instance across zones. Do not make a backup container public by accident.