media YT Video 330 The hard drive is the primary longterm storage device used in personal computers Hard drives are not volatileeven without power data remains stored on the drive Hard drives come in three sizes for personal computers ID: 816236
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Slide1
Hard Drive Components
1.5 Install and configure storage devices and use appropriate
media
YT Video 3:30
Slide2The hard drive is the primary long-term storage device used in personal computers
Hard drives are not volatile-even without power data remains stored on the drive
Hard drives come in three sizes for personal computers
3.5" size for desktops
2.5" size for laptop computers
1.8" size for low-end laptops and other equipment such as MP3 players
2
The Hard Drive
Top to bottom: 1", 1.8", 2.5", 3.5”, hard drives
Slide3Hard Drive Types
Hard drives come in 2 types
The most common type of hard drives with moving parts are known as hard disk drives (HDDs)
The newer and expensive technology that has no moving parts are called solid state drives (SSDs)
In addition, some drives use a combination of these 2 technologies and are known as hybrid drives
5
Slide4Slide5Slide6Magnetic Hard Drives
HDDs are generally larger in capacity than a SSD
A magnetic hard drive has a mixture of both physical and logical components
Platters
Read/write heads
Actuator/actuator arms
The physical components of a hard drive include:
Tracks
Sectors
Clusters
The logical components of a hard drive include:
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Slide7Magnetic Hard Drives
Physical Components
Platters
, or disks, can be written to on both sides
Hard drives can have multiple platters, which are extremely smooth and cannot be exposed to outside airA tiny dust particle can cause damage to the drive
Every platter requires 2
read/write heads, one on the top and one on the bottom (if a drive has 4 platters it needs 8 heads)
Read/Write heads move across the platters as they rotate on a spindleThe heads ride on a very thin cushion of air hundreds of times smaller than a human hair7
Slide8Magnetic Hard Drives
Physical Components
The
actuator controls the movement of the actuator arm
The
actuator arm moves back and forth around an central axis point (called the actuator axis)
This allows the read/write head to be positioned on different areas of the platter
Today hard drives use a voice coil motor to move the actuator arm8
Slide9Magnetic Hard
Drives
Logical Components
Each platter is logically divided into a thousand or more tracks, which are circular areas on the disk
When the head is over a track, it can read or write data
Tracks are logically divided into
sectors and they are the smallest storage unit on a disk
Sector markings are written to a magnetic drive before it leaves the factory in a process called low-level formattingA sector often stores 512 bytes but with new hard drives the sector size is moving to 4096 bytes (4K)10
Slide10Magnetic Hard Drives
Logical Components
A
cluster is a group of multiple sectors
Files are written to a cluster, but if the file is bigger than a single cluster, it is written to multiple clusters
In a perfect world a file will be written to clusters that are next to each other11
Slide11Slide12Slide13A solid state drive (SSD) uses memory chips to store data instead of metal spinning parts
SSDs are usually built using NAND flash memory which retains data when power is disconnected
The lifespan of a SSD is based on the number of write operations to the drive
SSDs are more expensive, but faster, more reliable, last longer, and use less power than HDDs
13
Solid State Drives
YT Video 4:05
Slide1414
s
olid-state drives by Toshiba
Slide15Hard Drive Interface Standards
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Interface standards define data speeds and transfer methods within a system
They also define types of cables and connectors
Interfaces can be divided into 2 categories, internal and external standards
Internal standards include PATA, SATA, and SCSI (pronounced scuzzy)
External standards include
eSATA
, USB,
Firewire
,
Thunderbolt, and
SCSI
Slide16Integrated Drive Electronics (IDE) appeared in the 1980s
In the early 1990s IDE was standardized as ATA, later named ATA-1, and the maximum drive size was 137 GB
In the mid 1990s enhancements of the original IDE were marketed as Extended IDE (EIDE) and later standardized as ATA-2
In the early 2000s ATA was upgraded to ATA-7, SATA was introduced, and EIDE was renamed to PATA to differentiate it from SATA
Originally IDE and ATA were only for hard drives but ATA Packet Interface (ATAPI) provided standards so they could be used with optical drives (CD or DVD-ROM)
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Internal PATA Drives
PM (800 series) Video 8:09
Slide1718
Timeline of interface standards used by internal drives
Slide1818
Summary of ATA interface standards
Slide19Internal PATA
Drives
Parallel ATA (PATA) sends data in parallel
Allows 1 or 2 connectors on a motherboard
Allows 2 drives on a single cable (master/slave)PATA has been mostly replaced by SATA
Types of PATA ribbon cables
The first drives used a 40-pin cable
40 pins and 40 wiresThe cable has a colored strip down one side (Pin 1)ATA-5 defined the use of a new 80-conductor cable
(blue connector) 40 pins and 80 wires Maximum recommended length of either is 18”
19
80-conductor cable and 40-conductor cable; they are about
the same width, but the 80-conductor cable has many more and finer wires
Slide20Serial ATA standards use a serial data path rather than the traditional parallel data path used by PATA drives
Some advantages SATA has over PATA include:
SPEED:
SATA is faster than PATA and is used by all drive types
NO MASTER/SLAVE:
Multiple connectors are easier to configure with no master
or slave configurations neededHOT SWAPPING: SATA supports hot-swapping (hot-plugging)Connect and disconnect drive while system is runningCABLE LENGTH: The SATA maximum cable length of 40 inches is more than twice that of a PATA cable length
AIRFLOW: SATA cables don’t hinder airflow (narrower than PATA)
20Internal SATA DrivesPM (800 series) Video 4:03
A SATA data cable and SATA power cable
Slide2121
Slide2222
SATA standards
Slide23Small Computer System Interface (SCSI) has been around a long time
While it has provided better performance than PATA drives it is more expensive and harder to implement
With the popularity of SATA drives, SCSI drives are largely falling out of use
SCSI is different from PATA and SATA in that SCSI devices connect together in a string of devices called a daisy chain
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Internal & External SCSI
PM
(800 series) Video
9:35
Slide2424
A SCSI host adapter card can support
internal and external SCSI devices
Slide25Internal &
External
SCSI
Each SCSI device is assigned a SCSI ID (0 - 15)
Most people set the host adapter to 7
SCSI chains use a terminating resistor
Plugged into last device at both ends of the chain
Reduces electrical noise or interference on the cable
Categories of SCSI Connectors
8-bit (narrow SCSI)
16-bit (wide SCSI)
25
Slide26External Drive Interfaces
eSATA
drives use a special shielded serial ATA cable
and the port is shaped different than internal SATAeSATA supports speeds of 6 Gb/s
Motherboards can provide external SATA (
eSATA) ports
USB 3.0 supports speeds up to 5 Gb/s and cables over 16’ long
Almost every computer has USB ports
Firewire 800 supports speeds up to 800 Mb/s and cables over 15’ long
Many computers have a Firewire port
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