Title: Magnetic Storage
1Magnetic Storage
- CIS 145
- Microcomputer Servicing
- Kelvin Kempfer
2Magnetic Storage
- The Hard Disk Drive (HDD)
- How Disk Space is Organized
- Hard Drive Size Limitations
- Hard Disk Drive Interfaces
- How to solve hard drive installation problems
3The Hard Disk Drive (HDD)
- Hard Drive
- Primary computer storage device
- Secondary Memory
- Spins, reads and writes one or more fixed disk
platters
- Storage medium in desktop and laptop computers
- The term hard differentiates high-capacity
rigid disks made aluminum or glass from
low-capacity floppy disks made of plastic
4First Microcomputer Hard Disk Seagate introduced
the first hard disk for personal computers in
1979. At 5MB, the ST506 held 10 times as much as
the RAMAC at a fraction of its size. (Image
courtesy of Seagate Technology, Inc.)
5The Hard Disk Drive (HDD)
- A sealed metal housing.
- Protection against dust particles
- An electrical motor connected to a spindle
- Spends as many as 8 magnetically coated platters
- Todays platters are coated with an alloy about
three millionths of an inch thick
- Several thousand revolutions/minute
6How a Hard Disk Drive Works
- Logic board receives commands from the drives
controller.
- Managed by the operating system and BIOS
- Translates commands into voltage fluctuations
- Forces the head actuator to move read/write
heads
- Makes sure the spindle turning the platters is at
a constant speed
- Tells the drive head to read or write
7How a Hard Disk Drive Works
- A head actuator pushes and pulls the read/write
heads across the surfaces of the platters with
critical precision.
- Aligns heads with the tracks
8How a Hard Disk Drive Works
- Read/write heads slide in unison across both the
top and bottom surfaces of the platters.
- Write the data coming from the disk controller by
aligning the magnetic fields of particles
- Read the data by detecting the polarities of
particles that have already been aligned
9Spindle
Actuator
Platters or disks
Read/write head
10- Have one, two, or more platters
- Stack together
- Spin in unison
Platters or disks
11How Disk Space is Organized
- When a disk is manufactured,
- Its surface is on a large area.
- An organizational structure must be imposed that
uniquely names each physical location on the
disk
- Drive controller can specify the exact physical
spot where a given bit of data should be written
or retrieved
- Cylinders, Heads, Sectors , and Tracks
- CHS
12How Disk Space is Organized
- Each side or surface of one hard drive platter is
called a head.
- The number of heads in the same as the number of
disk platter surfaces available for writing data
- Almost all magnetic disks are double-sided
- There is a separated read/write head for each
side.
- The numbering starts at the bottom side of the
bottom platter with 0.
- An average number of heads for a hard disk today
is 16.
13How Disk Space is Organized
- A track is a combination of the cylinder and head
location over the writeable portion of the hard
disk.
- In a multiplatter or multiside disk, each side
has its own separate tracks
- A 1.44MB floppy disk has 40 tracks per side
- A large hard disk can have tens of thousands
14How Disk Space is Organized
- A sector is the smallest unit that can be read
from or written to a disk.
- Pie slices made by lines that cross over the
track lines.
- Each sector holds exactly 512 bytes of data
- Modern 1.44MB floppy disks use 36 sectors/track
- A typical IDE hard drive usually has 63
sectors/track
- A SCSI hard drive can have 600 or more sectors
per track
15How Disk Space is Organized
- Cylinders are the concentric writeable tracks
found on the surface of the platters that make up
the hard drive.
- The stack of tracks accessible at a given
position constitutes a cylinder.
- The number of cylinders a drive has in the same
as the number of tracks on a single disk side
- All areas of a disk at a certain in/out head
position on all disk sides combined
16(No Transcript)
17How Disk Space is Organized
- Calculating the capacity of the drive
- Cylinders x heads x sectors/track x 512
bytes/sector
- Divide by
- 1024 KB
- 1048576 MB
- 1073741824 GB (Typical size)
18Hard Drive Size Limitations
- Three possible settings in most BIOS Setup
programs (translations)
- CHS (Cylinder, Head and Sector) Mode or Normal
Mode
- Extended CHS Mode (ECHS) or Large Mode
- Logical Block Addressing (LBA)
19Hard Drive Size Limitations
- CHS (Cylinder, Head and Sector) Mode or Normal
Mode
- The addressing is the same coming into and going
out of the BIOS
- Straight pass-through
- This setting turns off any translation and limits
the drive size to 528MB
- A drive can have no more than 1,024 cylinders, 16
heads, 63 sectors per track and 512 bytes per
sector
20Hard Drive Size Limitations
- Extended CHS Mode (ECHS) or Large Mode
- This was the original type of translation
- Used for drives between 504 MB and 8.4 GB
- The hard drive controller sends the logical
geometry to the system BIOS
- Logical geometry presents information not exactly
equal to the physical geometry yields the actual
capacity of the drive
- Controller BIOS masks the actual organization of
the drive from system BIOS and software (White
Lie)
- Large mode is not as popular as LBA
21Hard Drive Size Limitations
- 3. Logical Block Addressing (LBA)
- LBA is the most popular way of dealing with large
drives if the OS is using system BIOS to access
the drive.
- Most popular way of dealing with drives larger
than 504 MB
- Only way of dealing with drives larger than 8.4
GB.
- Drives larger than 504 MB are called
large-capacity drives
- Motherboard BIOS that support them is called
enhanced BIOS
- Simply views the drive as a long list of
sequential numbers
22Hard Drive Size Limitations
- You may need a BIOS update if
- Your BIOS was made before 1996
- Does not support ECHS or LBA
- A BIOS between 1996 and 1998
- Might support LBA but not have Enhanced BIOS
Services for Disk Drives support
23Hard Drive Size Limitations
- Enhanced BIOS Services for Disk Drives
- Introduced in 1998
- Breaks the 8 GB barrier
- Supports drives up to 18 trillion gigabytes
- A BIOS feature not a drive feature
24Hard Drive Size Limitations
- Device Drivers
- Used to bypass the system BIOS
- Communicates directly with the hard drive
controller
- Windows NT/2000/XP uses this method
- Windows 9x has its own 32-bit, protected-mode
device drivers to access hard drives
- Can also support system BIOS
25Hard Drive Size Limitations
- If you install an old drive that has been using
Standard CHS into a new system that autodetects
it and sets it up to use LBA, you could lose
access to the existing data on that drive. In
such case you would manually configure the drive
in BIOS to use Standard CHS, retrieve its data
and then switch it over to LBA and repartition it.
26Hard Drive Size Limitations
- Other BIOS settings
- Multisector transfers
- Specifies the number of sectors in each block
transfer from the hard drive to memory
- Disabled, 2, 4, 8, or 16
- 16 is usually the right setting
- Self-Monitoring and Reporting Tool (SMART)
- A technology for monitoring drive performance and
reporting any irregularities or changes that
might signal impending failure.
27Hard Drive Performance
- Timing
- Access time
- The average amount of time it takes for the
read/write head to move to the requested sector
- The sum of seek time and latency period
- Seek time
- The average time it takes the read/write head to
move to the requested track
- Latency period
- The time it takes for the requested sector to
spin underneath the read/write head after the
read/write head moves to the requested track
28Hard Drive Performance
- Timing
- Data Transfer rate
- Determined according to the method by which data
are transferred to and from the platters.
- Bits/second or Bytes/second
- Dependent on the speed of the disk and the
density of the data on the disk
29Formatting
- Low-Level Formatting
- The process that defines the tracks and sectors
on the platters of the hard drive
- High-Level Formatting
- The process of writing the file system structure
on the disk so that it can be used to store
programs and data
- The disk can be made bootable by copying the
operating systems boot files
30Hard Disk Drive Interfaces
- EIDE (Enhanced Integrated Device Electronics)
- ANSI (American National Standards Institute)
- An extension of IDE (Integrated Drive
Electronics)
- Standard defining how hard drives relate to the
system
- Tape drives, CD-ROM and Zip drives
- First standard was ATA-2
- Allows up to four devices
- ATAPI Advanced Technology Attachment Packet
Interface)
31Hard Disk Drive Interfaces
- EIDE
- IDE/ATA (1988)
- Speeds range from 2.1MB/s to 8.3 MB/s
- Limited to no more than 528 MB
- Supports PIO and DMA
- 40-pin ribbon cable
- Introduced the Identify Drive command
(autodetect)
- ATA-2/Fast ATA (1996)
- Speeds up to 16.6 MB/s
- Breaks the 528 MB barrier
- Allows up to four IDE devices
- Supports PIO and DMA transfer modes
- ATA-3 (Improved version of ATA-2) (1997)
- SMART
32Hard Disk Drive Interfaces
- EIDE (continued)
- Ultra ATA, Fast ATA-2, Ultra DMA, DMA/33
- ATA-4
- Speeds up to 33.3 MB/s
- Defined a new DMA mode but only supports slower
PIO modes
- Supported 80-wire ribbon caable
- Introduced ATAPI standard
- Ultra ATA/66, Ultra DMA/66
- ATA-5
- Speeds up to 66.6 MB/s
- Uses an 80-conductor cable
- Improves signal integrity
33Hard Disk Drive Interfaces
- EIDE (continued)
- Ultra ATA/100
- Speeds up to 100 MB/s
- Uses an 80-conductor cable
- Ultra ATA/133
- Speeds up to 133 MB/s
- Supports drives larger than 137 GB
- Uses an 80-conductor cable
- ATA/ATAPI-6
- A part of the ATA/133 standard that supports
drives larger than 137 GB.
34Features 60/80/100/120G Available 60G
formatted Capacity Per disk Ultra ATA - 100
FDB (Fluid Dynamic Bearing) Motor
Load/Unload Technology GMR Head Technology
with Wireless Suspension Design SilentSeek
Silentec Hybrid Latch Technology
35Hard Disk Drive Interfaces
- EIDE Cabling Methods
- Parallel ATA (PATA)
- 80-conductor
- Looks similar to the 40-conductor
- Fits the same 40-pin IDE connector
- Has twice the number of conductors when compared
to the 40-conductor
- Serial ATA cable
- Fewer pins than a parallel cable
- Fasted than ATA/100
- More expensive
36Hard Disk Drive Interfaces
37Hard Disk Drive Interfaces
- Transfer Modes
- Obsolete
- Programmed Input/Output
- DMA
- UltraDMA (UDMA)
- Also known as UltraATA
38Hard Disk Drive Interfaces
- Transfer Modes
- Programmed Input/Output
- Five different modes (0 - 4)
- PIO-0 (3.3 MB/s)
- PIO-4 (16.67 MB/s)
39Hard Disk Drive Interfaces
- Transfer Modes
- Direct Memory Addressing (DMA)
- Regular
- Uses DMA controller on the mother board
- Bus Mastering
- Higher speed DMA functionality built into the
south bridge of the chipset
- Takes advantage of the PCI bus for DMA transfers
- Modes 0 - 2 (4.16 - 16.67 MB/s)
40Hard Disk Drive Interfaces
- Northbridge Connects CPU to RAM, AGP bus, PCI
Express bus, Built-in display Adapter
Southbridge Connects CPU to ATA (IDE) Drives,
USB bus, FireWire bus, Serial port, Parallel
port, Built-in audio, ISA bus (earlier PCs)
41Hard Disk Drive Interfaces
- Transfer Modes
- UltraDMA (UDMA)
- Also known as UltraATA
- A high-speed transfer mode for disk drives that
improves upon DMA and allows transfer rates of up
to 100MB/s
- Enable UltraDMA and it does the rest
42Hard Disk Drive Interfaces
- When a modern BIOS autodetects a modern IDE
drive, it will set the PIO/DMA to Disabled
because it employs UltraDMA instead. You should
not attempt to enable PIO or DMA on such a drive
because it will only slow it down.
43Reading a File from Disk
- User makes a request
- Chooses Drive
- Operating System checks Virtual File Allocation
Table (VFAT)
- FAT16
- FAT32
- NTFS
44Reading a File from Disk
- From the VFAT it gets the address of the first
cluster that contains the beginning of the file
along with addresses of any other clusters that
might be used to store the file.
VFAT File 1st Cluster Mom.doc 3 Budget.xls 4
Rock.mp3 5
Cluster Address Cluster Track Sectors 3
1 2,3,4,5 4 1 6,7
,8,9
5 2 1,2,3,4
45Reading a File from Disk
- OS provides address information to BIOS
- BIOS issues commands to the disk drives
controller
- Controller moves the read/write head over the
clusters containing the file.
- Correct order to read the file from the beginning
to the end.
- Data is read from the disk through the BIOS.
- BIOS places data in RAM
46Purchasing a Hard Drive
- What type of drive do you need?
- What type of controller do you have?
- SCSI is faster and more reliable.
- SCSI is more expensive.
- Do you have any more connections on your
controller?
- Most computers have one or two IDE controllers
with two connections on each controller.
- SCSI will allow up to seven devices to be
connected to one controller.
47IDE Hard Drive InstallationHardware
- 1. Screw in the hard drive to the open brackets
(rails) in the case. This step sometimes requires
you to create a place to house your hard drive.
If the computer case cannot accept another hard
drive, consider purchasing a different case for
the computer. - 2. Connect the ribbon cable to the adapter card,
lining up pin 1 with the red band on the ribbon
cable.
- 3. Insert a power cord coming off the power
supply to the hard drive.
48IDE Hard Drive InstallationHardware (cont.)
- 4. IDE drives must be defined in the CMOS SETUP.
Some newer motherboards have a built-in
AUTO-DETECT feature that correctly identifies the
new hard drive. Older computers require you to
manually define the hard drive in SETUP. - 5. If its an older hard drive, use either Type
47 or User Defined when setting up the drive.
Its important to add the cylinders, heads and
sector information included in the drive. This
information usually can be found on the back of
the hard drive. - 6. After you restart the computer, the system
BIOS recognizes the drive. Next, run the DOS
FDISK program to define partitions, and then
FORMAT the unit.
49Installing a Second IDE Hard Drive
- 1. On the second drive, set the DIP switches so
that the second drive is set as the slave to
the older master drive.
- 2. Screw in the hard drive to the open brackets
(rails) in the case. This step sometimes requires
you to create a place to house your hard drive.
If the computer case cannot accept another hard
drive, consider purchasing a different case for
the computer. - 3. Connect the ribbon cable to the hard drive,
lining up pin 1 with the red band on the ribbon
cable.
50Installing a Second IDE Hard Drive (cont.)
- 4. Insert a power cord coming off the power
supply to the hard drive. IDE drives must be
defined in the CMOS SETUP. Some newer
motherboards have a built-in AUTO-DETECT feature
that correctly identifies the new hard drive.
Older computers require you to manually define
the hard drive in SETUP. - 5. If its an older hard drive, use either Type
47 or User Defined when setting up the drive.
Its important to add the cylinders, heads and
sector information included in the drive. This
information usually can be found on the back of
the hard drive.
51Installing a Second IDE Hard Drive (cont.)
- 6. After you restart the computer, the system
BIOS recognizes the drive. Next, run the DOS
FDISK program to define partitions, and then
FORMAT the unit.
52Hard Disk Partitioning
- Reduces wasted space on larger hard drives.
- Cluster size can be as large as 64K.
- When a file is written, it will consume an entire
cluster, even if it is only a few bytes in size.
- An average document file is 14K, but it will use
an entire cluster. On a very large drive, this
would waste 50K.
53CHKDSK.EXE and ScanDisk
- Prior to MS-DOS 6.0, you could use a utility
called CHKDSK.EXE. This utility is used to
recover lost allocation units and to repair
cross-linked files. - ScanDisk utility does the same as CHKDSK, but it
also includes a program that will scan the
surface of your disk for defects and attempt to
repair them.
54Defrag
- Defrag is a hard disk utility that gets rid of
any file fragments that are on the drive.
- Fragmented files slow down hard drive access.
- Defrag can move all the free space together on
the drive. This is very helpful when creating
swapfiles.
55Troubleshooting IDE Hard DrivesPossible Causes
- Hard drive configuration in CMOS is incorrect
- Virus on hard drive
- Incorrect or loose cabling of the hard drive to
the controller
- Corrupt or defective boot sector or partition
- MS-DOS corrupted
- Invalid entry in the AUTOEXEC.BAT or CONFIG.SYS
file
- Hardware conflict caused by the addition of a new
piece of hardware
56Hard Drive Error Codes and Possible Solutions
- Hard disk configuration error
- Check CMOS
- Loose cable
- Hard disk 0 failure
- Check CMOS
- Check power supply to the hard drive
- Hard disk controller failure
- Loose controller cable
- Invalid drive specification
- Check CMOS
57Hard Drive Error Codes and Possible Solutions
(cont.)
- Error selecting drive
- Check CMOS
- Check FDISK partition
- Invalid command interpreter
- Check CMOS
- Reload MS-DOS to the boot sector
- No boot device available
- Check CMOS
- Reload MS-DOS to the boot sector
58Hard Drive Error Codes and Possible Solutions
(cont.)
- Missing operating system
- Check CMOS
- Reload MS-DOS to the boot sector
- General Failure reading drive C or Not ready
reading drive C
- Check CMOS
- Run CHKDSK or SCANDISK
59Floppy Drives
- First PC floppy drive could hold only 160K.
- PC/XT came with a 5.25-inch 360K.
- Largest capacity for a 5.25-inch is 1.2MB.
- Do not attempt to format a 360K diskette to
1.2MByou will have multiple bad sectors, and if
you write data to the disk, you run the risk of
losing the data.
60Floppy Drives (cont.)
- The first 3.5-inch was introduced in the late
1980s and could hold 720KB.
- A hard plastic case and a spring-loaded cover
protects the disk. This results in a longer life
expectancy over the 5.25-inch floppy disks.
- 3.5 inch diskettes can now store up to 2.88MB,
but the norm is 1.44MB.