CompTIA Network+ Preparation · lesson 20 of 30 · 25 min
Storage Technologies
Network storage allows multiple systems to share storage resources over a network. The Network+ exam covers three main storage architectures: DAS, NAS, and SAN.
DAS (Direct-Attached Storage) — storage connected directly to a single server (internal drives, external USB/eSATA). Not shared over the network. Fast but not scalable for multiple servers.
NAS (Network-Attached Storage) — dedicated storage device connected to the network. Accessed via file-sharing protocols (SMB/CIFS for Windows, NFS for Linux/Unix). Appears as a network share. Easy to set up and manage. Good for file sharing.
SAN (Storage Area Network) — dedicated high-speed network connecting servers to storage arrays. Accessed at the block level (appears as a local disk to the server). Uses Fibre Channel or iSCSI. High performance, high cost. Used in enterprise data centers.
SAN Protocols
Fibre Channel (FC) — dedicated high-speed network for SAN. Uses FC switches and HBAs (Host Bus Adapters). Very fast and reliable but expensive. Separate physical infrastructure from Ethernet.
iSCSI (Internet Small Computer Systems Interface) — runs SCSI commands over TCP/IP. Uses existing Ethernet infrastructure — lower cost than Fibre Channel. Good performance with 10 GbE or faster.
FCoE (Fibre Channel over Ethernet) — encapsulates Fibre Channel frames over Ethernet. Converges FC and Ethernet on the same physical network. Requires lossless Ethernet (DCB).
NFS (Network File System) — Unix/Linux file-sharing protocol. NAS uses NFS for Linux clients. NFSv4 adds security improvements.
SMB/CIFS — Windows file-sharing protocol. NAS uses SMB for Windows clients. SMB3 adds encryption and improved performance.
Exam Tip
NAS = file-level access (SMB/NFS). SAN = block-level access (FC/iSCSI). iSCSI runs over TCP/IP — uses existing Ethernet. Fibre Channel requires dedicated infrastructure. DAS is not shared over the network.
RAID Levels
RAID (Redundant Array of Independent Disks) — combines multiple drives for performance and/or redundancy.
RAID 0 (Striping) — data split across drives. Best performance. No redundancy — one drive fails = all data lost.
RAID 1 (Mirroring) — data duplicated on two drives. Full redundancy. 50% storage efficiency. Good for OS drives.
RAID 5 (Striping with parity) — data and parity striped across 3+ drives. Can survive one drive failure. Good balance of performance, capacity, and redundancy.
RAID 6 — like RAID 5 but with double parity. Can survive two drive failures. Requires 4+ drives.
RAID 10 (1+0) — mirrored pairs that are striped. Requires 4+ drives. High performance and redundancy. Can survive multiple failures if not in the same mirror pair.
Key Terms
Key Terms
Knowledge Check — 10 Questions
Network+ — Network Storage
NAS provides which type of storage access?
- Block-level
- File-level
- Object-level
- Direct-attached
Answer: File-level
NAS = file-level access via SMB (Windows) or NFS (Linux). SAN = block-level (appears as a local disk).
iSCSI runs SCSI commands over:
- Fibre Channel
- TCP/IP (Ethernet)
- USB
- InfiniBand
- Answer: TCP/IP (Ethernet)
iSCSI encapsulates SCSI commands in TCP/IP packets — uses existing Ethernet infrastructure, making it cheaper than Fibre Channel.
Which RAID level provides NO redundancy?
- RAID 1
- RAID 5
- RAID 0
- RAID 10
Answer: RAID 0
RAID 0 (striping) has no redundancy — one drive failure loses all data. It is used purely for performance.
RAID 5 requires a minimum of how many drives?
- 2
- 3
- 4
- 5
Answer: 3
RAID 5 requires at least 3 drives — data and parity are striped across all drives. Can survive one drive failure.
Which storage type appears as a local disk to the server?
- NAS
- SAN
- NFS share
- SMB share
Answer: SAN
SAN provides block-level storage — the server sees it as a local disk. NAS provides file-level shares that appear as network drives.
Fibre Channel SANs require:
- Standard Ethernet switches
- Dedicated FC switches and HBAs
- iSCSI initiators
- NFS servers
- Answer: Dedicated FC switches and HBAs
Fibre Channel requires its own infrastructure: FC switches, HBAs (Host Bus Adapters) in servers, and FC cabling — separate from Ethernet. RAID 6 can survive:
- One drive failure
- Two drive failures
- Three drive failures
- No drive failures
- Answer: Two drive failures
RAID 6 uses double parity — can survive two simultaneous drive failures. Requires 4+ drives.
Windows clients access NAS using which protocol?
- NFS
- iSCSI
- SMB/CIFS
- FTP
Answer: SMB/CIFS
Windows uses SMB (Server Message Block) / CIFS for file sharing. Linux/Unix uses NFS. NAS supports both.
RAID 10 combines:
- Striping and parity
- Mirroring and striping
- Parity and mirroring
- Three-way mirroring
- Answer: Mirroring and striping
RAID 10 (1+0) = mirrored pairs that are then striped. Combines RAID 1 redundancy with RAID 0 performance. Requires 4+ drives.
DAS stands for _____ -Attached Storage.
Answer: Direct
DAS = Direct-Attached Storage — connected directly to one server, not shared over the network.
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