Chapter 3.6 Storage Devices

HDD Design

Data Stored magnetically, Non-Volatile, Stored on Moving Platters, Actuator Arms Move Read-Write Heads

HDD 3.5in Form Factor

Desktops

HDD 2.5in Form Factor

Laptops, Mobile Devices

HDD 1.8in Form Factor

Ultrabooks, Compact Devices

HDD 5400 RPM Performance

Laptops

HDD 7200 RPM Performance

Workstations

HDD 10-15k RPM Performance

High Performance Servers

HDD Industry Standard Interface

SATA

SATA 1.0 Performance

150 Mbps

SATA 2.0 Performance

300 Mbps

SATA 3.0 Performance

600 Mbps

Hot Swapping

Replacing a Drive without Powering Down the System

SSD Design

No Moving Parts, Electronic Storage (NAND Chips), Non-Volatile

SSD Performance Benefits Compared to HDD

Smaller, Faster, More Shock Resistant, and Require less Power

SSD Overwriting Downside

SSDs cannot overwrite data directly, They must Erase Blocks of Data at a Time, Impacting Lifespan

NAND (Acronym)

Not AND, Logic Gate

SSD Form Factors

2.5in, M.2

M.2 Form Factor Design

Plugs Directly to Motherboard, Defined by its Dimensions (2280 = 22mm x 80mm), Always 22mm Wide

M.2 Connection Interfaces

MiniSATA or NVMe

NVMe (Acronym)

Non-Volatile Memory Express

NVMe (Use Case)

Optimized Interface for M.2 SSDs, Utilizes PCIe, Increased Speed Compared to SATA

PCIe (Acronym)

Peripheral Component Interconnect Express

Storage Type Used by Flash Drives, SD Cards and Multimedia Cards

NAND Chips

RAID (Acronym)

Redundant Array of Independent Drives

RAID (Use Case)

Combining Multiple Drives to Enhance Performance, Capacity, and Redundancy. Managed by a RAID Controller Card.

RAID 0 Striping (Use Case)

Striped Across Mulitple Drives, for Performance, Only Used when Data Loss is Acceptable

RAID 1 Mirroring (Use Case)

Provides Redundancy, Capacity is halved, Creates Identical Copy of Drive

RAID 5 Distributed Parity (Use Case)

Striped Across All Drives, Parity Information is Distributed Across All Drives, Combination of Redundancy and Performance

RAID 6 Doubled Parity (Use Case)

RAID 5’s Combination of Striping and Parity, 6 Can Withstand 2 Simultaneous Drive Failures Compared to RAID 5’s 1 Failure

RAID 10 Stripe of Mirrors (Use Case)

Combined Striping and Mirroring, Drives are Arranged as Mirrored Pairs, Tolerates failure of 2 Drives of Different Pairs, Expensive!