3.4 Storage Devices/RAID

What is an (HDD)?

Hard Disk Drive

• Magnetic storage

• Uses spinning platters + moving actuator arm

What is an (SSD)?

Solid-State Drive

• No moving parts

• Uses flash memory

What can you do to increase the lifespan of you SSD?

Disable regularly scheduled defragmentation of the SSD

There’s no need for it and defragmentation will do alot of writes witch are limited on an SSD

What is PCI Express storage?

Peripheral Component Interconnect Express

• high-speed connection directly to motherboard

• used by modern SSDs

Benefits:

• very high throughput

• low latency

What is NVMe?

Non-Volatile Memory Express

• protocol designed specifically for SSDs

• runs over PCIe

Advantages:

• lower latency

• much faster than SATA

NVMe = SSD optimized protocol

What is SATA used for?

• connects storage devices (HDD/SSD)

• uses Advanced Host Controller Interface AHCI protocol

Speed:

• up to 6 Gbps (~600 MB/s)

Originally designed for hard drives, not SSD speeds.

What is SAS?

Serial Attached SCSI (Small Computer System Interface)

• enterprise storage interface

• faster and more reliable than SATA

What is SAS used for?

Enterprise servers and storage arrays

What is mSATA?

mini-SATA

• smaller version of SATA

• used in laptops

Status:

• mostly replaced by M.2

What is the M.2 interface?

• compact SSD form factor

• no cables (plugs directly into motherboard)

Can use:

• SATA

• PCIe (NVMe)

Identify the M.2 SSD Key

M key

Identify the M.2 SSD Key

B + M Key

Identify the M.2 SSD Key

B Key

What are flash drives?

• portable storage using EEPROM flash memory

  • electrically erasable programmable read-only memory

Features:

• limited write cycles

What are the key characteristics of optical drives?

• Slow; mainly for archival media

• Formats: CD, DVD, Blu-Ray

RAID purpose?

• Protects data with multiple drives

• Not a backup

What does RAID stand for, and what are the common RAID levels?

• RAID = Redundant Array of Independent (Inexpensive) Disks

• RAID 0 – Striping (no redundancy)

• RAID 1 – Mirroring (full redundancy)

• RAID 5 – Striping + 1 parity drive

• RAID 6 – Striping + 2 parity drives

• RAID 10 (1+0) – Stripe of mirrors (nested RAID)

“Zero Stripes, One Mirror, Five Parity, Six Double, Ten Mirrors Striped.”

• 0 → Zero Stripes → RAID 0 = striping only, no redundancy

• 1 → One Mirror → RAID 1 = mirroring

• 5 → Five Parity → RAID 5 = stripe + 1 parity drive

• 6 → Six Double → RAID 6 = stripe + 2 parity drives

• 10 → Ten Mirrors Striped → RAID 10 = stripe of mirrors

What is RAID 0 and its characteristics?

• Purpose = Stripe across drives → fast

• No redundancy → one failure = data loss

Identify the RAID type

RAID 0

What is RAID 1 and its characteristics?

• Mirrors data across 2 drives → full redundancy

• Safe if one drive fails

• Slower write speed (data copied to both drives)

• Faster read speeds than single drive

Identify the RAID type

RAID 1

What is RAID 5 and its characteristics?

• Stripe data across 3+ drives with 1 parity drive

• Combines performance + redundancy

• Can survive one drive failure

Identify the RAID type

RAID 5

What is RAID 6 and its characteristics?

• Stripe data across 4+ drives with 2 parity drives

• Can survive two drive failures

• Slightly slower than RAID 5 due to extra parity

Identify the RAID type

RAID 6

What is RAID 10 and its characteristics?

• Nested RAID → stripe of mirrors

• Combines speed (striping) + redundancy (mirroring)

• Can survive multiple drive failures depending on which drives fail

Identify the RAID type

RAID 10