Transcript Hard Drive Technologies

Hard Drive Technologies
Joe Cicero
Northeast Wisconsin Technical College
This Presentation Will Cover…
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Types of Hard Drives
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Hard Drive Parts
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Platter/s, Read/Write Head/s, Actuator Arm/s,
Actuator, Spindle, etc.
How A Hard Drive Works
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SATA, ATA, SCSI, etc
Modifying Magnetic Media
Hard Drive Math
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Why 1000 = 1024
Continued…
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Hard Drive Controllers
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Configuring Hard Drives
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Jumpers, Master, Slave, Cable Select, IDE /
EIDE Cable capabilities, etc.
Partitioning A Hard Drive
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IDE, EIDE, SCSI, SATA, RAID, etc
Primary, Extended, Logical Drives
Format of Hard Drive
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FAT, NTFS, EXT3, etc
Continued…
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Hard Drive Maintenance
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Chkdsk, cleanmgr, defrag, limitations, etc.
Types of Hard Drives
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Hard drives come in many different types.
Some of these are:
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ATA
 ATA : Also
known as IDE (Integrated Drive
Electronics) supports one or two hard drives per
cable, a 16-bit interface and PIO (Programmed
Input/Output).
ATA Hard Drive
Types of Hard Drives Continued:
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SATA
 SATA or
S-ATA, an evolution of the ATA physical
storage interface. Serial ATA is a serial link -- a
single cable with a minimum of four wires creates a
point-to-point connection between devices.
Transfer rates for Serial ATA begin at 150 MBps
and SATA II 300MBps.
 One of the main design advantages of Serial ATA
is that the thinner serial cables facilitate more
efficient airflow inside a form factor and also allow
for smaller chassis designs.
SATA Hard Drive
Types of Hard Drives Continued:
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SCSI
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This acronym is pronounced "scuzzy" and stands for Small
Computer Systems Interface. IDE and SATA are much more
common and less expensive.
The biggest difference between SCSI, ATA and SATA is that
while SCSI has a processor integrated into the controller, ATA
and SATA make greater use of the system processor to serve
that function.
SCSI is more expensive and also more flexible and generally the
drive spins faster – but it should be noted that spinning faster
doesn’t necessarily make it work faster with the OS.
With a single SCSI card you can have 15 or more devices
whereas typically you are only allowed to have 4 devices with an
ATA/IDE or SATA system.
SCSI Hard Drive
Hard Drive Parts
A - Platter/s
B - Read/Write Head/s
C - Actuator Arm/s
D - Actuator
E - Spindle
How A Hard Drive Works
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The banks of polarized molecules in the disk's
coating are themselves tiny magnets that create
a magnetic field through which the read/write
head passes. The movement of the head
through the magnetic field generates an
electrical current that travels in one direction or
the other through the wires leading from the
head. The direction the current flows depends
on the polarities pf the bands. By sensing the
directions in which the current is moving, the
computer can tell if the read / write head is
passing over a 1 or a 0.
How A Hard Drive Works
Hard Drive Math
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kilo is 1,000 in the decimal system.
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Hence, one kilometer is a 1,000 meters and one kilogram is 1,000
grams because we are using the decimal system.
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However, in the binary system, a kilo is 1,024.
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As you can see the kilo in the binary system (1,024) is close in value
to the kilo in the decimal system (1,000) and many people use 1
kilobyte as a synonym of 1,000 bytes.
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Therefore, a file of 6 KB contains 6,144 bytes (6 x 1024 bytes) not
6000 bytes. A 2.2 Gig hard drive partition would have 2,252,800,000
bytes or would be 2.2528 GB.
Hard Drive Controllers
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IDE
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Integrated Device Electronics. A hard drive interface system developed
by a group of manufacturers whereby the controller system was
integrated into the drive; all of the components were within the hard
drive unit removing the need to have a separate controller.
It should be NOTED that most older 40 wire IDE cables DO NOT
support Cable Select!
EIDE
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A design that improves on the Drive limitations of the IDE design. EIDE
designs can use up to four devices (split into two pairs). For each pair of
devices, one of the devices is the master; the drive electronics on the
master control both the master drive and (if applicable) the secondary
slave unit attached.
It should be NOTED that the Master Drive should be plugged into the
end of the cable if you want it to be a master device and are setting it to
Cable Select!
Hard Drive Controllers
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SCSI
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Small Computer Systems Interface, a high-speed
communications protocol that allows computers,
samplers, and disk drives to communicate with one
another. Pronounced "scuzzy.“
It should be noted that when using SCSI interfaces
you can have up to 7 (or even 15) devices.
SATA
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Serial ATA is an evolutionary replacement for the
Parallel ATA physical storage interface.
Hard Drive Controllers
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RAID (Redundant Array of Independent Disks). A collection of disk drives
that offers increased performance and fault tolerance. There are a number
of different RAID levels. The three most commonly used are 0, 1, and 5:
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* Level 0: striping without parity (spreading out blocks of each file
across multiple disks).
* Level 1: disk mirroring or duplexing.
* Level 2: bit-level striping with parity
* Level 3: byte-level striping with dedicated parity. Same as Level 0,
but also reserves one dedicated disk for error correction data. It provides
good performance and some level of fault tolerance.
* Level 4: block-level striping with dedicated parity
* Level 5: block-level striping with distributed parity
* Level 6: block-level striping with two sets of distributed parity for extra
fault tolerance
* Level 7: Asynchronous, cached striping with dedicated parity
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Configuring Hard Drives
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Most IDE drives have jumpers that select
the "master" or "slave" role on the
controller, but modern drives also have a
"CS" or "Cable select" pin. This allows the
IDE cable itself to select the drive's role:
all drives that have the CS jumper set
allow the cable to choose which device is
the master and which is the slave.
Configuring Hard Drives
When a drive is on the cable alone it
should be set to Master OR Cable Select –
providing it is plugged into the end
connector.
 When there are two drives, the drive that
should be bootable should be set to
Master or Cable Select – providing it is
plugged into the end connector.
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Configuring Hard Drives
When there are two drives, one that is
bootable, one that is not; The bootable
drive should be set to Master or Cable
Select – providing it is plugged into the
end connector.
 When there are two drive, both that are
bootable; They should be both set to
Cable Select.
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Configuring Hard Drives
IDE / EIDE
Configuring Hard Drives
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SATA does not require Master Slave settings.
SATA drops the master/slave shared bus of
PATA, giving each device a dedicated cable and
dedicated bandwidth. While this requires twice
the number of host controllers to support the
same number of SATA devices
Partitioning A Hard Disk
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Primary Partitions:
A primary partition may contain an operating system along with any number of data
files (for example, program files, user files, and so forth). Before an OS is installed,
the primary partition must be logically formatted with a file system compatible to the
OS.
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If you have multiple primary partitions on your hard disk, only one primary partition
may be bootable and active at a time. The active partition is the partition from which
an OS is booted at computer startup.
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Primary partitions other than the active partition are hidden if their file system type is
not recognized, preventing their data from being accessed. Thus, the data in a
primary partition can be accessed (for all practical purposes) only by the OS installed
on that partition.
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If you plan to install more than one operating system on your hard disk, you probably
need to create multiple primary partitions; most operating systems can be booted
only from a primary partition.
Partitioning A Hard Disk
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Extended Partitions:
The extended partition was invented as a way of getting
around the arbitrary four-partition limit. An extended partition
is essentially a container in which you can further physically
divide your disk space by creating an unlimited number of logical
partitions.
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An extended partition does not directly hold data. You
must create logical partitions within the extended partition
in order to store data. Once created, logical partitions
must be logically formatted, but each can use a different file
system.
Partitioning A Hard Disk
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Logical Partitions
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Logical partitions may exist only
within an extended partition and are meant
to contain only data files and operating
systems that can be booted from a logical
partition (for example, Linux, Windows NT,
and so forth).
Formatting A Hard Disk
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Formatting a hard disk arranges the magnetic media in a pattern so that the
operating system knows where it is in relation to the data on the disks
surface
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When doing a clean install of Windows XP, after you’ve selected the
partition where XP will be installed, you are presented with the option to
format the drive or partition. The format options are:
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Format the partition using the NTFS file system (Quick)
Format the partition using the FAT file system (Quick)
Format the partition using the NTFS file system
Leave the current file system intact (no changes)
The difference between the regular format versus the quick format is
whether or not the volume is scanned for bad sectors using the chkdsk
command. Both methods remove the files from the volume.
Format Choices
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FAT16
The FAT16 file system was introduced way back with MS–DOS in
1981. It was designed originally to handle files on a floppy drive, and
has had minor modifications over the years so it can handle hard
disks, and even file names longer than the original limitation of 8.3
characters, but it's still the lowest common denominator.
The biggest advantage of FAT16 is that it is compatible across a
wide variety of operating systems, including Windows 95/98/Me,
OS/2, Linux, and some versions of UNIX. By default many of these
OS’s can read FAT16!
The biggest problem of FAT16 is that it has a fixed maximum
number of clusters per partition, so as hard disks get bigger and
bigger, the size of each cluster has to get larger. In a 2–GB partition,
each cluster is 32 kilobytes, meaning that even the smallest file on
the partition will take up 32 KB of space. FAT16 also doesn't support
compression, encryption, or advanced security using access control
lists.
Format Choices
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FAT32
The FAT32 file system, originally introduced in Windows 95 Service
Pack 2, is really just an extension of the original FAT16 file system
that provides for a much larger number of clusters per partition. As
such, it greatly improves the overall disk utilization when compared
to a FAT16 file system.
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However, FAT32 shares all of the other limitations of FAT16, and
adds an important additional limitation—many operating systems
that can recognize FAT16 will not work with FAT32—most notably
Windows NT, but also Linux and UNIX as well.
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Now this isn't a problem if you're running FAT32 on a Windows XP
computer and sharing your drive out to other computers on your
network—they don't need to know (and generally don't really care)
what your underlying file system is.
Format Choices
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NTFS
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The NTFS file system, introduced with first version of Windows NT,
is a completely different file system from FAT. It provides for greatly
increased security, file–by–file compression, quotas, and even
encryption. It is the default file system for new installations of
Windows XP.
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There are DOS and Legacy Windows drivers to allow older systems
to read NTFS. Unix/Linux also has a NTFS driver, so these OS’s
can read NTFS partitions.
Hard Drive Maintenance
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Chkdsk
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If your Windows operating system experiences a
problem, you can use the Chkdsk disk repair utility
included in the operating system to check the file
system on each logical partition and check the disk
surface for unreadable or corrupted sectors.
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The Chkdsk utility creates and displays a status
report for a disk based on the file system used.
Chkdsk also lists and corrects errors on the disk. You
can run Chkdsk from your Windows operating
system. If you cannot start your operating system
because of the problem, you can run Chkdsk from the
Windows Recovery Console.
Hard Drive Maintenance
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CleanMGR
Cleanmgr.exe is designed to clear
unnecessary files from your computer's hard
disk. You can configure Cleanmgr.exe with
command-line switches to clean up the files
you want. You can then schedule the task to
run at a specific time by using the Scheduled
Tasks tool.
 It is important to clean your disk of
unnecessary files BEFORE you defrag it!
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Hard Drive Maintenance
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Sometimes when you install a program or create a data file, the file
ends up chopped up into chunks and stored in multiple locations on
the disk. This is called fragmentation.
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There's a simple solution to file fragmentation: use Windows Disk
Defragmenter (Start –> Programs –> Accessories –> System Tools –
> Disk Defragmenter). This utility, commonly called Defrag, gathers
all the scattered file fragments and writes them into adjacent
clusters, so each file occupies a contiguous section of the disk.
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Defrag works by moving slabs of data to unused parts of the disk, in
order to open up a large free section of space. It then assembles the
fragmented parts of a file and writes them in one complete piece to
the cleared space; it then does the same with the next file; and so
on until the entire disk is defragmented.
Hard Drive Maintenance
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Defrag Limitations
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Defrag cannot defragment open files or
Operating System Files that are in use.
To over come this limitation you can use
specialty software programs.
Pagedfrg – is a utility to defragment the
pagefiles
 Contig – is a utility to defragment individual
files.
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Questions