computer system
Storage
• Storage media hold the data being access, as well as the
files the system needs to operate and data needs to be
saved
 
Hard Disk 
• ( hard dis is a thic magnetic dis encased in a thicer
 protective shell
• %an hold more information compare to other storage
devices
• I#) "Integrated #rive )lectronics$
• )I#) ")nhanced I#)$ *+(T(
1 (T( – (dvanced Technology (ttachment
 
computers
• Its also popular interface for other drive such as %#'
34, ##'34
• (T( speed measurements are defined in H6. )arlier
(T( speeds were 77H6 and then 88H6. 9ewer (T(
devices can run at :;; H6, and :77H6, with the
newest devices running as fast as :88 H6.
• : +(T( connector can connect up to 2 devices
• &ecause both devices share the same channel, devices
must be configured properly to avoid conflicts by set up
the <=umper>
• -se fastest standard appropriate for range of the
system and si6e of the drive
• ust be supported by the 4S, system &I4S on
motherboard, and firmware on the drive
• -ltra (T(*:;;? most popular 
• )I#) "+(T($ have a slower speed than S(T( in term
of transferring data
a primary and a secondary
• )ach connection can support up to two I#) devices
for a total of four devices on a system
• +rimary I#) channel, master device
• +rimary I#) channel, slave device
• Secondary I#) channel, master device
• Secondary I#) channel, slave device
 
SATA 
• ( serial (T( cable is thinner and has fewer pins than an
I#) cable.
• Serial transfer rates begin at :.5 @bps ":5; &*s$, the
latest S(T( can up to 7@bps
• The cable length can be up to one meter .
• )ach S(T( drive has its own channel, with a single drive
connected to each cable and port.
 
removed while the system is running.
• S(T( devices have a special power connector. Some
 power supplies include S(T( power connectors. If not,
use a converter to attach to a normal drive power cable
• Supports eAternal devices through the )Aternal
S(T( "also called eS(T($ standard. eS(T( is
faster than -S& and !irewire.
 
SCSI
Few PCs use Small Computer System Interface (SCSI) drives SCSI drives are generally faster and
 
 
• Is typically used in servers that have high availability and
speed reBuirements.
• +rovides better performance than +(T( or S(T(.
• Though S%SI devices are most commonly used for tape
storage devices and hard diss, they can also be used for
devices such as %#'34 drives, scanners, and printers
 
• (ctive and passive terminator  • (ctive terminator uses voltage regulators, better than  passive terminator
• +assive terminator wors with resistors driven by small amount of electricity
• S%SI support up to C drives per interface
• Support internal, eAternal and even combination of
internal and eAternal interface.
The mechanism and mechanical arm that physically moves
across tracs and sectors to read or write data. There are
usually two "one on each side$ of these per platter.
• #is*+latter 
agnetic dis to write the data, every hard dis have
different amount of diss
• Spindle
The motor to spin the dis when the writing and reading
 process eAecutes.
The platter or set of platters that magnetically hold data.
•   Track 
near the center of the platter and outward.
•   Sector
The spaces "pie shaped$ in between eBually spaced lines
that emanate from the center to the outside edge of the
 platter.
• The drive must physically fit into the computer. Dith the
eAception of an eAternal drive, the most common si6ed
drives are as follows?
• 2.5E for noteboos
• 7.5E "most common$
• 5.25E "older drives$
 
when Fudging the value of a hard drive. The following
concepts and measurements define a hard driveGs overall
 performance?
• 3+ "3evolutions +er inute$ identifies how fast a hard
dis spins. %ommon I#) drives rotate their disGs at 5;;
rpm or C2;; rpm.
• See time is the amount of time reBuired to find data. (
 
• SS# stands for Solid State #rive
•  Kie a memory stic, there are no moving parts to an
SS#. 3ather, information is stored in microchips.
•  9(9# – &ased flash memory 'L non volatile
 
HDD SSD
Information is store in storage platter Information is stored in microchips
Have mechanical arm to read and write data
-sed embedded controller to perform write and read
%heaper )Apensive
 9o sound and vibration
• #iscussion
 
• ( technology that allowed computer users to achieve
high levels of storage reliability from low'cost and less
reliable +%'class dis'drive components, via the
techniBue of arranging the devices into arrays for
redundancy
configured to #AID &
replicate data among multiple hard dis drives.
• Two ey design goals?
a. increased data reliability.
 b. increased input*output performance.
• Dhen multiple physical diss are set up to use 3(I#
technology, they are said to be in a  RAID array.
• This array distributes data across multiple diss, but the
array is seen by the computer user and operating system as
one single dis.
as 3(I# :;, sometimes identified "and more
appropriately so$ as 3(I# :N;.
• 3(I# :; wors by striping and mirroring your data
across at least two diss.
•  It improves performance because the computer can get
data off more than one dis simultaneously.
• 3(I# :; is secure because mirroring duplicates all your
data. ItGs fast because the data is striped across two or
more diss, meaning chuns of data can be read and
written to different diss simultaneously.