1.2 Compare and contrast networking appliances, applications, and functions
📘CompTIA Network+ (N10-009)
✅ Definition
A Storage Area Network (SAN) is a specialized high-speed network that provides access to shared storage devices (such as disk arrays or tape libraries) to multiple servers.
It allows storage to be separated from individual servers and centralized into one dedicated storage network.
In simple terms, a SAN connects servers and storage devices over a dedicated network, allowing data to be stored and accessed efficiently.
🔹 Purpose of SAN
The main goals of a SAN are:
- Centralized storage management – All storage is managed in one place rather than being spread across individual servers.
- Improved performance – Data transfers occur over a high-speed, dedicated network separate from the main LAN.
- High availability and redundancy – If one path or device fails, others can take over to ensure continuous access.
- Scalability – Storage capacity can be increased easily without changing or shutting down servers.
- Efficient data access and backup – Supports faster backups, replication, and disaster recovery.
🔹 SAN vs NAS (for exam comparison)
| Feature | SAN (Storage Area Network) | NAS (Network-Attached Storage) |
|---|---|---|
| Connection Type | Block-level access | File-level access |
| Network Used | Uses a dedicated storage network (Fibre Channel, iSCSI, etc.) | Uses existing LAN (Ethernet) |
| Performance | High speed, low latency | Slower compared to SAN |
| Accessed By | Servers (treated as local disks) | Clients/users (via file sharing protocols like SMB/NFS) |
| Use Case | Enterprise environments, databases, virtualization | File sharing, backups, smaller networks |
💡 Exam Tip:
Remember — SAN = block-level storage, NAS = file-level storage.
🔹 How SAN Works (Basic Components)
A SAN is built using three key components:
1. Hosts (Servers)
- These are the systems that request and use data.
- They connect to the SAN using Host Bus Adapters (HBAs) (special network cards for storage traffic).
2. Storage Devices
- These include disk arrays, SSD arrays, or tape libraries.
- The data is stored here and managed centrally.
3. SAN Fabric (Network Infrastructure)
- The connection medium between hosts and storage.
- Uses switches, cables, and protocols optimized for storage traffic.
🔹 SAN Technologies and Protocols
There are several types of SAN technologies based on the protocol used:
1. Fibre Channel (FC) SAN
- A high-performance, specialized network technology designed for SANs.
- Uses Fibre Channel switches and fiber optic cables.
- Provides very high speed (up to 128 Gbps) and low latency.
- Common in enterprise data centers.
2. iSCSI SAN (Internet Small Computer System Interface)
- Uses TCP/IP over Ethernet networks.
- More affordable than Fibre Channel.
- Converts SCSI commands into IP packets to transfer over standard Ethernet.
- Suitable for small to medium-sized businesses.
3. Fibre Channel over Ethernet (FCoE)
- Combines Fibre Channel protocol with Ethernet infrastructure.
- Reduces the need for separate cabling and hardware.
- Requires Data Center Bridging (DCB) to ensure lossless Ethernet.
4. NVMe over Fabrics (NVMe-oF)
- A newer high-speed protocol that allows NVMe storage devices to communicate over networks.
- Extremely fast and efficient, used in modern data centers and cloud infrastructure.
🔹 SAN Topologies (Ways SAN can be arranged)
- Point-to-Point
- Direct connection between one server and one storage device.
- Simple but limited.
- Arbitrated Loop
- Devices connected in a loop (like a ring topology).
- One device transmits at a time.
- Switched Fabric
- Uses Fibre Channel switches to interconnect multiple servers and storage devices.
- Most common in enterprise SANs.
- Provides scalability, redundancy, and high performance.
🔹 SAN Zoning
SAN zoning is a security and access control method used within Fibre Channel SANs.
- It defines which servers (initiators) can connect to which storage devices (targets).
- Configured at the switch level.
- Types:
- Hard zoning: Based on switch port configuration (hardware-enforced).
- Soft zoning: Based on device names or addresses (software-enforced).
💡 Purpose: Prevents unauthorized access and limits interference between devices.
🔹 Benefits of Using SAN
- Centralized storage and management
- Improved data availability and reliability
- Faster backup and disaster recovery
- High performance for data-intensive applications
- Scalable and flexible storage expansion
- Supports virtualization environments (VMware, Hyper-V, etc.)
🔹 SAN in IT Environments (Practical IT Context)
- Used in data centers to connect large numbers of servers to shared storage pools.
- Critical for virtualized environments, where multiple virtual machines need access to the same storage.
- Supports high-availability clusters — if one server fails, another can access the same data.
- Used for database servers, mail servers, and enterprise applications needing high-speed data access.
- Commonly integrated with backup and replication systems for disaster recovery.
🔹 SAN Management Concepts
- LUN (Logical Unit Number):
- A unique identifier used to represent a logical portion of storage within the SAN.
- Servers access storage using LUNs instead of physical drives.
- Multipathing:
- Provides multiple physical paths between the server and the storage.
- Ensures redundancy and load balancing.
- Storage Virtualization:
- Combines multiple physical storage devices into a single, logical storage pool for better management and flexibility.
🔹 Common SAN Vendors (for awareness)
(Not for memorization but useful to recognize)
- Dell EMC
- NetApp
- HPE (Hewlett Packard Enterprise)
- IBM
- Hitachi Vantara
🔹 Key Exam Points Summary
| Concept | What to Remember |
|---|---|
| SAN | Dedicated high-speed network for shared storage access |
| Type of Access | Block-level |
| Protocols | Fibre Channel, iSCSI, FCoE, NVMe-oF |
| Components | Hosts, Storage devices, SAN fabric |
| Zoning | Controls device access for security |
| Use Case | Enterprise storage, virtualization, backup |
| Advantage | High performance, scalability, centralized storage management |
🧠 Quick Exam Tips
- SAN ≠ NAS — focus on the block vs file-level difference.
- Know that Fibre Channel and iSCSI are the two main protocols.
- Understand the role of HBAs, switches, and zoning.
- SAN is often used in enterprise and virtualization setups.
- SANs provide redundancy, performance, and centralized control.
