SAN technology is used where the storage architecture needs to provide block-level storage to servers and other systems through a dedicated storage environment.
Practical example: NAS, DAS or SAN?
For shared office files, NAS is often the natural architecture to evaluate first.
Scenario: A 25-user office needs shared departmental files, central backup storage and controlled user access.
A NAS is a natural candidate because it provides file services over the existing network. A directly attached enclosure would tie the storage more closely to one host. A SAN would make more sense where servers require shared block storage, for example in a more complex virtualisation environment.
Decision: For this example, start by evaluating NAS capacity, drive type, network speed, snapshots and backup replication. Do not deploy SAN architecture merely because it sounds more enterprise.
Common mistakes and selection checklist
Common mistakes
- Choosing NAS, DAS or SAN because one architecture sounds more enterprise rather than because it fits the workload.
- Sizing storage only by terabytes and ignoring IOPS, throughput, network speed, snapshots and backup.
- Using one storage system as both primary data and the only backup copy.
What happens if you get it wrong?
Users can experience slow file access or applications can be constrained by the wrong storage path. More importantly, a storage failure or data-loss event can affect both production data and the supposed recovery copy.
Selection checklist
- Decide whether applications need file storage, block storage or storage attached to one host.
- Estimate current usable capacity and realistic growth.
- Identify performance, network and concurrency requirements.
- Check drive type, RAID options, snapshots and expansion.
- Design backup and off-system recovery independently.
A resilient array keeps services available during some drive failures. Separate backups provide recovery from deletion, corruption, malware and site loss.
Block storage
A SAN presents storage as blocks to connected hosts. The operating system and applications can then use the storage in the way required by the workload.
SAN vs NAS
NAS generally provides file-level storage services over a network, while a SAN provides block-level storage. The distinction affects how applications and operating systems interact with the storage.
Infrastructure requirements
SAN environments can involve storage systems, controllers, switches, transceivers, fibre connectivity and appropriate host interfaces. Compatibility and design are important.
When does SAN make sense?
A SAN is generally considered when the performance, availability, centralisation and management requirements justify a dedicated storage architecture.
The storage system, connectivity, switches, host adapters and software configuration all form part of the solution.
Confirm the exact product specification, supported configuration and compatibility before ordering. Platform generation, firmware, licences and optional components can change what a product supports.