Hard Drive
Content
Hard Drive Technologies
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Overview
In this chapter, you will learn to
± Explain how hard drives work ± Identify and explain ATA hard drive interfaces ± Identify and explain SCSI hard drive interfaces ± Describe how to protect data with RAID ± Explain how to install drives ± Configure CMOS and install drivers
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Historical/Conceptual
How Hard Drives Work
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
The Hard Drive
Hard drives are composed of individual disks or platters The platters are made up of aluminum and coated with a magnetic medium Two tiny read/write heads service each platter
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
The Hard Drive
The closer the read/write heads are to the platter, the more densely the data can be packed on to the drive Hard drives use a tiny, heavily filtered aperture to equalize the air pressure between the exterior and interior of the hard drive Platters spin between 3500 and 10,000 rounds per minute (RPM)
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Data Encoding
Hard drives store data in tiny magnetic fields called fluxes The flux switches back and forth through a process called flux reversal
Hard drives read these flux reversals at a very high speed when accessing or writing data
± Fluxes in one direction are read as 0 and the other direction as 1
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Data Encoding
Encoding methods used by hard drives are
± Run length limited (RLL)
Data is stored using ³runs´ that are unique patterns of ones and zeroes Can have runs of about seven fluxes
± Partial Response Maximum Likelihood (PRML)
Uses a powerful, intelligent circuitry to analyze each flux reversal Can have runs of about 16 to 20 fluxes Significantly increased capacity (up to 1 TB)
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Arm Movement in the Hard Drive The stepper motor technology and the voice coil technology are used for moving the actuator arm
± Moves the arms in fixed increments or steps ± Only seen in floppies today
The voice coil technology uses a permanent magnet surrounding the coil on the actuator arm to move the arm
± Automatically parks drive over non-data area when power removed
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Geometry
Geometry is used to determine the location of the data on the hard drive
± CHS (cylinders, heads, sectors)
Used to be critical to know geometry
± Had to enter into CMOS manually
Today, geometry stored on hard drive
± BIOS can query hard drive for geometry data
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Heads
Heads
± Number of read/write heads used by the drive to store data ± Two heads per platter (top and bottom) ± Most hard drives have an extra head or two for their own usage, so the number may not be even
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Cylinders
Cylinders ± Group of tracks of the same diameter going completely through the drive
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Sectors per Track
Sectors per track
± Number of slices in the hard drive ± 512 bytes per sector
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Obsolete Geometry
Might see in older systems Write precompensation cylinder
± The specific cylinder from where the drive would start writing data farther apart
Internal sectors physically smaller External sectors physically larger This identified cylinder where spacing changed
Landing zone
± Unused cylinder as ³parking place´ for heads
Referred to as Lzone, LZ, Park Needed for older drives using stepper motors
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
IT Technician
CompTIA A+ Essentials
ATA²The King
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Hard Drive Interfaces
ATA interfaces dominate today¶s market
± Many changes throughout years ± Parallel ATA (PATA) historically prominent ± Serial ATA (SATA) since 2003
Small Computer System Interface (SCSI)
± Pronounced ³Scuzzy´ ± Used in many high-end systems
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
ATA Overview
Cable 40-pin 40-pin 40-pin 40-pin Keywords PIO and DMA EIDE ATAPI SMART Ultra BIOS Upgrade ATA/33 ATA/66 Big Drive ATA/133 SATA Speed 3.3 MBps to 8.3 MBps 11.1 MBps to 16.6 MBps Max size 504 MB 8.4 GB
ATA-1 ATA-2 ATA-3 ATA-4 INT13 ATA-5 ATA-6 ATA-7
11.1 MBps to 16.6 MBps 8.4 GB 16.7 MBps to 33.3 MBps 8.4 GB 137 GB 44.4 MBps to 6.6 MBps 100 MBps 133 MBps to 300 MBps 137 GB 144 PB 144 PB
40-pin 80-wires 40-pin 80-wires 40-pin 80-wires 7-pin
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
ATA-1
Programmable I/O (PIO)²traditional data transfer
± 3.3 MBps to 8.3 MBps
DMA²direct memory access
± 2.1 MBps to 8.3 MBps
Allowed two drives (one master, one slave)
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
ATA-2
Commonly called EIDE (though a misnomer) Added second controller to allow for four drives instead of only two Increased size to 8.2 GB Added ATAPI
± Could now use CD drives
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
ATA-3
Self-Monitoring Analysis and Reporting Technology
± S.M.A.R.T.
No real change in other stats
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
ATA-4
Introduced Ultra DMA Modes
± Ultra DMA Mode 0: 16.7 MBps ± Ultra DMA Mode 1: 25 MBps ± Ultra DMA Mode 2: 33 MBps
Ultra DMA Mode 2 also called ATA/33
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
INT13 Extensions
ATA-1 standard actually written for hard drives up to 137 GB
± BIOS limited it to 504 MB due to cylinder, head, and sector maximums ± ATA-2 implemented LBA to fool the BIOS, allowing drives to be as big as 8.4 GB
INT13 Extensions extended BIOS commands
± Allowed drives as large as 137 GB
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
ATA-5
Introduced newer Ultra DMA Modes
± Ultra DMA Mode 3: 44.4 MBps ± Ultra DMA Mode 4: 66.6 MBps
Ultra DMA Mode 4 also called ATA/66 Used 40-pin cable, but had 80 wires
± Blue connector²to controller ± Gray connector²slave drive ± Black connector²master drive
ATA/66 cable
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
ATA-6
³Big Drives´ introduced Replaced INT13 & 24-bit LBA to 48-bit LBA Increased maximum size to 144 PB
± 144,000,000 GB
Introduced Ultra DMA 5
± Ultra DMA Mode 5: 100 MBps ATA/100 ± Used same 40-pin, 80-wire cables as ATA-5
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
ATA-7
Introduced Ultra DMA 6
± Ultra DMA Mode 6: 133 MBps ATA/133 ± Used same 40-pin, 80-wire cables as ATA-5 ± Didn¶t really take off due to SATA¶s popularity
Introduced Serial ATA (SATA)
± Increased throughput to 150 MBps to 300 MBps
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
IT Technician
CompTIA A+ Technician
ATA-7
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Serial ATA
Serial ATA (SATA) creates a point-to-point connection between the device and the controller ± Hot-swappable ± Can have as many as eight SATA devices ± Thinner cables resulting in better airflow and cable control in the PC ± Maximum cable length of 39.4 inches compared to 18 inches for PATA cables
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Serial ATA
More on SATA
± PATA device my be connected to SATA using a SATA bridge ± Can have as many as eight SATA devices
Add more SATA functionality via a PCI card
eSATA
± External SATA
eSATA Port
± Extends SATA bus to external devices
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
SCSI Small Computer System Interface
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
SCSI
Pronounced ³Scuzzy´ Been around since ¶70s Devices can be internal or external Historically the choice for RAID
± Faster than PATA ± Could have more than four drives
SATA replacing SCSI in many applications
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
SCSI Chains
A SCSI chain is a series of SCSI devices working together through a host adapter The host adapter is a device that attaches the SCSI chain to the PC All SCSI devices are divided into internal and external groups The maximum number of devices, including the host adapter, is 16
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Internal Devices
Internal SCSI devices are installed inside the PC and connect to the host adapter through the internal connector Internal devices use a 68-pin ribbon cable
Cables can be connected to multiple devices
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
External Devices
External SCSI devices are connected to host adapter to external connection of host adapter External devices have two connections in the back, to allow for daisy-chaining A standard SCSI chain can connect 15 devices, including the host adapter
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
SCSI IDs
Each SCSI device must have a unique SCSI ID The values of ID numbers range from 0 to 15 No two devices connected to a single host adapter can share the same ID number No order for the use of SCSI IDs, and any SCSI device can have any SCSI ID
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
SCSI IDs
The SCSI ID for a particular device can be set by configuring jumpers, switches, or even dials Use your hexadecimal knowledge to set the device ID
± Device 1 = ± Device 7 = ± Device 15 = 0001 0111 1111 Off, Off, Off, On Off, On, On, On On, On, On, On
Host adapters often set to 7 or 15 but can be changed
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Termination
Terminators are used to prevent a signal reflection that can corrupt the signal Pull-down resistors are usually used as terminators Only the ends of the SCSI chains need to be terminated Most manufacturers build SCSI devices that self-terminate
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Protecting Data with RAID
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Protecting Data
The most important part of a PC is the data it holds
± Companies have gone out of business because of losing data on hard drives
Hard drives will eventually develop faults Fault tolerance allows systems to operate even when a component fails
± Redundant Array of Inexpensive Disks (RAID) is one such technology
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
RAID Level 0
Disk striping
± Writes data across multiple drives at once ± Requires at least two hard drives ± Provides increased read and writes
Not fault tolerant
± If any drive fails, the data is lost
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
RAID Level 1
Disk mirroring/duplexing is the process of writing the same data to two drives at the same time
± ± ± ± Requires two drives Produces an exact mirror of the primary drive Mirroring uses the same controller Duplexing uses separate controllers
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
RAID Levels 2 to 4
RAID 2
± Disk striping with multiple parity drives ± Not used
RAID 3 and 4
± Disk striping with dedicated parity ± Dedicated data drives and dedicated parity drives ± Quickly replaced by RAID 5
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
RAID Level 5
Disk striping with distributed parity
± Distributes data and parity evenly across the drives ± Requires at least three drives ± Most common RAID implementation
Software-based RAID 5
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
RAID 5 (Stripe with Parity)
Decimal 0 1 2 3 4 22 4 0 0 0 0 1 21 2 0 0 1 1 0 20 1 0 1 0 1 0 Decimal 21 2 0 0 1 1 20 1 0 1 0 1 Odd Parity 1 0 0 1
0 1 2 3
0 0 1 1 Data
0 1 0 1 Data
1 0 0 1 Parity
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
RAID Level 6
Super disk striping with distributed parity
± RAID 5 with asynchronous and cached data capability
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Implementing RAID
SCSI has been the primary choice in the past
± Faster than PATA ± PATA allowed only four drives
SATA today viewed as comparable choice
± Speeds comparable to SCSI ± Dedicated SATA controllers can support up to 15 drives
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Hardware vs. Software
Hardware RAID
± Dedicated controller ± Operating system views it as single volume
Software RAID
± Operating system recognizes all individual disks ± Combines them together as single volume
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Personal RAID
ATA RAID controller chips have gone down in price Some motherboards are now shipping with RAID built-in The future is RAID
± RAID has been around for 20 years but is now less expensive and moving into desktop systems
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Connecting Drives
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Connecting Your Drive
Choosing your drive
± PATA, SATA, or SCSI ± Check BIOS and motherboard for support
Jumpers and cabling on PATA
± Master ± Slave ± Cable select
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Jumpers and Cabling
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Connecting SCSI Drives
First need compatible controller
± Different types of SCSI
Connect data cable
± Reversing this cable can damage drive, data, or both
Connect power
± Pin 1 goes to Pin 1
Configure SCSI IDs on drives and controller
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
BIOS Support: Configuring CMOS and Installing Drivers
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Configuring CMOS
Enable Controller Turn on Auto detection
PATA - IDE Channels 1 and 2
SATA - IDE Channels 3 to 6 (note no slaves)
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Boot Order
Identifies where computer will try to load an operating system
± Multiple devices configured ± First one with an OS will boot
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Device Drivers
ATAPI devices show up in CMOS, but true BIOS support comes from a driver at boot-up Serial ATA requires loading drivers for an external SATA controller and configuring the controller Flash ROM settings for the specific drive
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Overview
In this chapter, you will learn to
± Explain how hard drives work ± Identify and explain ATA hard drive interfaces ± Identify and explain SCSI hard drive interfaces ± Describe how to protect data with RAID ± Explain how to install drives ± Configure CMOS and install drivers
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Historical/Conceptual
How Hard Drives Work
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
The Hard Drive
Hard drives are composed of individual disks or platters The platters are made up of aluminum and coated with a magnetic medium Two tiny read/write heads service each platter
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
The Hard Drive
The closer the read/write heads are to the platter, the more densely the data can be packed on to the drive Hard drives use a tiny, heavily filtered aperture to equalize the air pressure between the exterior and interior of the hard drive Platters spin between 3500 and 10,000 rounds per minute (RPM)
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Data Encoding
Hard drives store data in tiny magnetic fields called fluxes The flux switches back and forth through a process called flux reversal
Hard drives read these flux reversals at a very high speed when accessing or writing data
± Fluxes in one direction are read as 0 and the other direction as 1
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Data Encoding
Encoding methods used by hard drives are
± Run length limited (RLL)
Data is stored using ³runs´ that are unique patterns of ones and zeroes Can have runs of about seven fluxes
± Partial Response Maximum Likelihood (PRML)
Uses a powerful, intelligent circuitry to analyze each flux reversal Can have runs of about 16 to 20 fluxes Significantly increased capacity (up to 1 TB)
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Arm Movement in the Hard Drive The stepper motor technology and the voice coil technology are used for moving the actuator arm
± Moves the arms in fixed increments or steps ± Only seen in floppies today
The voice coil technology uses a permanent magnet surrounding the coil on the actuator arm to move the arm
± Automatically parks drive over non-data area when power removed
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Geometry
Geometry is used to determine the location of the data on the hard drive
± CHS (cylinders, heads, sectors)
Used to be critical to know geometry
± Had to enter into CMOS manually
Today, geometry stored on hard drive
± BIOS can query hard drive for geometry data
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Heads
Heads
± Number of read/write heads used by the drive to store data ± Two heads per platter (top and bottom) ± Most hard drives have an extra head or two for their own usage, so the number may not be even
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Cylinders
Cylinders ± Group of tracks of the same diameter going completely through the drive
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Sectors per Track
Sectors per track
± Number of slices in the hard drive ± 512 bytes per sector
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Obsolete Geometry
Might see in older systems Write precompensation cylinder
± The specific cylinder from where the drive would start writing data farther apart
Internal sectors physically smaller External sectors physically larger This identified cylinder where spacing changed
Landing zone
± Unused cylinder as ³parking place´ for heads
Referred to as Lzone, LZ, Park Needed for older drives using stepper motors
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
IT Technician
CompTIA A+ Essentials
ATA²The King
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Hard Drive Interfaces
ATA interfaces dominate today¶s market
± Many changes throughout years ± Parallel ATA (PATA) historically prominent ± Serial ATA (SATA) since 2003
Small Computer System Interface (SCSI)
± Pronounced ³Scuzzy´ ± Used in many high-end systems
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
ATA Overview
Cable 40-pin 40-pin 40-pin 40-pin Keywords PIO and DMA EIDE ATAPI SMART Ultra BIOS Upgrade ATA/33 ATA/66 Big Drive ATA/133 SATA Speed 3.3 MBps to 8.3 MBps 11.1 MBps to 16.6 MBps Max size 504 MB 8.4 GB
ATA-1 ATA-2 ATA-3 ATA-4 INT13 ATA-5 ATA-6 ATA-7
11.1 MBps to 16.6 MBps 8.4 GB 16.7 MBps to 33.3 MBps 8.4 GB 137 GB 44.4 MBps to 6.6 MBps 100 MBps 133 MBps to 300 MBps 137 GB 144 PB 144 PB
40-pin 80-wires 40-pin 80-wires 40-pin 80-wires 7-pin
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
ATA-1
Programmable I/O (PIO)²traditional data transfer
± 3.3 MBps to 8.3 MBps
DMA²direct memory access
± 2.1 MBps to 8.3 MBps
Allowed two drives (one master, one slave)
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
ATA-2
Commonly called EIDE (though a misnomer) Added second controller to allow for four drives instead of only two Increased size to 8.2 GB Added ATAPI
± Could now use CD drives
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
ATA-3
Self-Monitoring Analysis and Reporting Technology
± S.M.A.R.T.
No real change in other stats
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
ATA-4
Introduced Ultra DMA Modes
± Ultra DMA Mode 0: 16.7 MBps ± Ultra DMA Mode 1: 25 MBps ± Ultra DMA Mode 2: 33 MBps
Ultra DMA Mode 2 also called ATA/33
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
INT13 Extensions
ATA-1 standard actually written for hard drives up to 137 GB
± BIOS limited it to 504 MB due to cylinder, head, and sector maximums ± ATA-2 implemented LBA to fool the BIOS, allowing drives to be as big as 8.4 GB
INT13 Extensions extended BIOS commands
± Allowed drives as large as 137 GB
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
ATA-5
Introduced newer Ultra DMA Modes
± Ultra DMA Mode 3: 44.4 MBps ± Ultra DMA Mode 4: 66.6 MBps
Ultra DMA Mode 4 also called ATA/66 Used 40-pin cable, but had 80 wires
± Blue connector²to controller ± Gray connector²slave drive ± Black connector²master drive
ATA/66 cable
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
ATA-6
³Big Drives´ introduced Replaced INT13 & 24-bit LBA to 48-bit LBA Increased maximum size to 144 PB
± 144,000,000 GB
Introduced Ultra DMA 5
± Ultra DMA Mode 5: 100 MBps ATA/100 ± Used same 40-pin, 80-wire cables as ATA-5
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
ATA-7
Introduced Ultra DMA 6
± Ultra DMA Mode 6: 133 MBps ATA/133 ± Used same 40-pin, 80-wire cables as ATA-5 ± Didn¶t really take off due to SATA¶s popularity
Introduced Serial ATA (SATA)
± Increased throughput to 150 MBps to 300 MBps
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
IT Technician
CompTIA A+ Technician
ATA-7
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Serial ATA
Serial ATA (SATA) creates a point-to-point connection between the device and the controller ± Hot-swappable ± Can have as many as eight SATA devices ± Thinner cables resulting in better airflow and cable control in the PC ± Maximum cable length of 39.4 inches compared to 18 inches for PATA cables
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Serial ATA
More on SATA
± PATA device my be connected to SATA using a SATA bridge ± Can have as many as eight SATA devices
Add more SATA functionality via a PCI card
eSATA
± External SATA
eSATA Port
± Extends SATA bus to external devices
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
SCSI Small Computer System Interface
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
SCSI
Pronounced ³Scuzzy´ Been around since ¶70s Devices can be internal or external Historically the choice for RAID
± Faster than PATA ± Could have more than four drives
SATA replacing SCSI in many applications
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
SCSI Chains
A SCSI chain is a series of SCSI devices working together through a host adapter The host adapter is a device that attaches the SCSI chain to the PC All SCSI devices are divided into internal and external groups The maximum number of devices, including the host adapter, is 16
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Internal Devices
Internal SCSI devices are installed inside the PC and connect to the host adapter through the internal connector Internal devices use a 68-pin ribbon cable
Cables can be connected to multiple devices
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
External Devices
External SCSI devices are connected to host adapter to external connection of host adapter External devices have two connections in the back, to allow for daisy-chaining A standard SCSI chain can connect 15 devices, including the host adapter
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
SCSI IDs
Each SCSI device must have a unique SCSI ID The values of ID numbers range from 0 to 15 No two devices connected to a single host adapter can share the same ID number No order for the use of SCSI IDs, and any SCSI device can have any SCSI ID
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
SCSI IDs
The SCSI ID for a particular device can be set by configuring jumpers, switches, or even dials Use your hexadecimal knowledge to set the device ID
± Device 1 = ± Device 7 = ± Device 15 = 0001 0111 1111 Off, Off, Off, On Off, On, On, On On, On, On, On
Host adapters often set to 7 or 15 but can be changed
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Termination
Terminators are used to prevent a signal reflection that can corrupt the signal Pull-down resistors are usually used as terminators Only the ends of the SCSI chains need to be terminated Most manufacturers build SCSI devices that self-terminate
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Protecting Data with RAID
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Protecting Data
The most important part of a PC is the data it holds
± Companies have gone out of business because of losing data on hard drives
Hard drives will eventually develop faults Fault tolerance allows systems to operate even when a component fails
± Redundant Array of Inexpensive Disks (RAID) is one such technology
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
RAID Level 0
Disk striping
± Writes data across multiple drives at once ± Requires at least two hard drives ± Provides increased read and writes
Not fault tolerant
± If any drive fails, the data is lost
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
RAID Level 1
Disk mirroring/duplexing is the process of writing the same data to two drives at the same time
± ± ± ± Requires two drives Produces an exact mirror of the primary drive Mirroring uses the same controller Duplexing uses separate controllers
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
RAID Levels 2 to 4
RAID 2
± Disk striping with multiple parity drives ± Not used
RAID 3 and 4
± Disk striping with dedicated parity ± Dedicated data drives and dedicated parity drives ± Quickly replaced by RAID 5
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
RAID Level 5
Disk striping with distributed parity
± Distributes data and parity evenly across the drives ± Requires at least three drives ± Most common RAID implementation
Software-based RAID 5
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
RAID 5 (Stripe with Parity)
Decimal 0 1 2 3 4 22 4 0 0 0 0 1 21 2 0 0 1 1 0 20 1 0 1 0 1 0 Decimal 21 2 0 0 1 1 20 1 0 1 0 1 Odd Parity 1 0 0 1
0 1 2 3
0 0 1 1 Data
0 1 0 1 Data
1 0 0 1 Parity
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
RAID Level 6
Super disk striping with distributed parity
± RAID 5 with asynchronous and cached data capability
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Implementing RAID
SCSI has been the primary choice in the past
± Faster than PATA ± PATA allowed only four drives
SATA today viewed as comparable choice
± Speeds comparable to SCSI ± Dedicated SATA controllers can support up to 15 drives
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Hardware vs. Software
Hardware RAID
± Dedicated controller ± Operating system views it as single volume
Software RAID
± Operating system recognizes all individual disks ± Combines them together as single volume
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Personal RAID
ATA RAID controller chips have gone down in price Some motherboards are now shipping with RAID built-in The future is RAID
± RAID has been around for 20 years but is now less expensive and moving into desktop systems
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Connecting Drives
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Connecting Your Drive
Choosing your drive
± PATA, SATA, or SCSI ± Check BIOS and motherboard for support
Jumpers and cabling on PATA
± Master ± Slave ± Cable select
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Jumpers and Cabling
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Connecting SCSI Drives
First need compatible controller
± Different types of SCSI
Connect data cable
± Reversing this cable can damage drive, data, or both
Connect power
± Pin 1 goes to Pin 1
Configure SCSI IDs on drives and controller
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
BIOS Support: Configuring CMOS and Installing Drivers
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Configuring CMOS
Enable Controller Turn on Auto detection
PATA - IDE Channels 1 and 2
SATA - IDE Channels 3 to 6 (note no slaves)
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Boot Order
Identifies where computer will try to load an operating system
± Multiple devices configured ± First one with an OS will boot
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Device Drivers
ATAPI devices show up in CMOS, but true BIOS support comes from a driver at boot-up Serial ATA requires loading drivers for an external SATA controller and configuring the controller Flash ROM settings for the specific drive
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
