1. Hard Drive Technologies
Chapter 9

2. How Hard Drives Work Platter-based Hard Drives Data Encoding
Platters
Magnetic coating
Read/write heads
Float above the surface
Actuator arms
Servo motor
Data Encoding
Flux reversals
Run length limited (RLL)
Partial Response Maximum Likelihood (PRML)
Moving the Arms
Stepper motor or voice coil motor
Geometry
Heads
Cylinders
Sectors per track
Write precompensation cylinder
Wider data spacing
Landing zone
Spindle speed
Solid-State Drives
Pages 316, 317

3. Parallel ATA Integrated Drive Electronics (IDE) ATA-1
PIO and DMA modes
Master and slave drives

4. Parallel ATA ATA-2 Sector translation Higher capacity with LBA
1024 cylinders, 16 heads, 63 sectors/track
Higher capacity with LBA
1024 cylinders, 256 heads, 63 sectors/track
ATAPI – Advanced Technology Attachment Packet Interface
More drives = 2 controllers
Increased speed
PIO modes 3, 4; Multi-word DMA modes 0, 1, 2

5. Parallel ATA
ATA-3
S.M.A.R.T.

6. Parallel ATA
ATA-4
Ultra DMA modes 0, 1, 2

7. Parallel ATA ATA-5 Faster Ultra DMA modes 3, 4 80 wire cable
Master on end, slave in middle

8. Parallel ATA
ATA-6
48-bit LBA
Ultra DMA mode 5

9. Serial ATA ATA-7 NVMe – Non-Volatile Memory Express eSATA Serial ATA
AHCI – Advanced Host Controller Interface
Hot swapping
Native command queueing
NVMe – Non-Volatile Memory Express
Supports communications between the OS and an SSD directly
eSATA
External devices

10. Protecting Data with RAID
RAID – Redundant Array of Independent (Inexpensive) Disks
RAID 0 – Disk Striping
RAID 1 – Disk Mirroring/Duplexing
RAID 2 – Disk Striping with Multiple Parity Drives
RAID 3, 4 – Disk Striping with Dedicated Parity
RAID 5 – Disk Striping with Distributed Parity
RAID 6 – Disk Striping with Extra Parity
Need 5 drives
Implementing RAID
Originally SCSI
Serial ATA possibly to take over
Hardware versus Software
Personal RAID
The Future of RAID