Secondary Storage ; Magnetic Disk ; Magnetic Tape Lecture -10 (LIC AAO ; IBPS ; SBI ; PO and Clerk) Video Lecture | Crash Course for SSC CGL (Hindi)

hello things welcome to current affairs
vendor free education revolution so
today's our topic is secondary storage
devices in our previous video lecture
videos is already cover our first two
memory devices which is registers cache
memories and main memory in this video
we will cover our secondary storage
devices which have so many parts so we
will cover in our some parts of
secondary storage devices so people if
you haven't seen my previous one lecture
then I request to you that please go
through that videos so that you will be
understand this video more easily so now
we are going to proceed before starting
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so now we are going to start our lecture
first of all I am going to tell you what
is the limitation of family makes like
primary memory or primary storage
because there is some limitation that is
why we need secondary storage devices
what are these limitation if you go
through my previous one lecture then you
will be easily notice that that in
timely memory it has
the limited capacity because the cost
per bit of storage hi you know that
primary storage has a limited storage we
already seen in the chart that primary
storage comes in some mb/s and your
secondary storage is greater than 100 GB
so you can say that it has a limited
capacity because of this the cost per
bit of storage is high how suppose your
primary memory consider it role is
rupees thousand rupees okay and you know
that drum has a very small size in
storage then it can if it is store
around 100 bits okay only hundred bits
then what is the cost per bit then the
cost per bit will be thousand divided by
100 which is 10 rupees per bit so you
can see that how much it is expensive
for storing data in a primary memory so
the because it is expensive than
secondary storage devices so this is the
first limitation of primary storage
device next one limitation of primary
store is that it is volatile I have
already told you what is the quality
means it the data which each has will be
destroyed when up our gate system okay
voilá time is now shrunk and I already
explained this volatize meaning here
that data is stored in H is lost when
the electric power is turned off or
interrupted these two main reserve you
can say these two main point will
limited the use of primary storage
device that is why we need our secondary
storage device now we are going to our
secondary storage device there are some
you can say there are some
characteristics of second just reduced
you or a device what it is first one is
used in a computer system to overcome
the limitation of primary storage
whatever the limitation of primary
storage these problem will not be here
in second a storage means it is
non-volatile and it is it has a large
storing capacity okay now the second
characteristic it has virtual unlimited
capacity what does it mean that what is
virtual unlimited capacity it means that
in your computer or laptop wrong if you
are round has a 16 MD or you can say 4
GB in size then you can never ever
increase its side suppose your data is
around 500 GB so you can never store it
in and even you cannot increase the size
to main memory from 50 GS or a 15 GB to
500 GB but in secondary memory what does
the advantage is this it will increase
the size virtually how I already told
you that your program have a larger
space okay suppose your marriage CD has
a very largest storage then what it will
be where we do we split our video we
will split our data in two CDs so well
how much data we have does not matter
because we can add more and more and
more CDs or pan drives or floppy these
are films in your secondary storage
devices and we can increase the storage
capacity of secondary storage device so
because the cost per bit of storage is
very low and you know that it has a
largest largest storing capacity but it
has a very small cost for you can say
that key that cost per bit of your
stories is very low next point is
operating speed for slower that of the
primary story what does it mean that
operating speed is far slower it means I
already told you about that I on to such
a person in our room it is very is if it
I want to see a search of our Salinas
country it is not impossible it way but
it will take a nice seam here
secondly women is has a very large space
has a very large capacity to store data
but the problem is that because it has a
very large space truth then then serves
to any data is become slower okay that
is why to operate anything which is
stored in your secondary storage device
will speed up its slower okay now we
came to our next point used to store
large volume of data on a permanent
basis if you want to store a large
amount of data which are in jeebies then
you have and you want to store in a
permanent basis okay then where you will
store it in a secondary storage device
and it is also known as auxilary memory
device these are the points of a storage
secondary storage device now we came
here to classify our second gen storage
device second is storage eva is
basically divided into two categories
which is GK access device and direct
access device in sequential access
device there is only one device cream
which is called which is called magnetic
tape and indirect Texas device there are
three subcategories first one is
magnetic disk second one is of the
optical disk third one is memory storage
device and many magnetic disks also
categorized into two subcategories first
one is floppy disk and next one is is
hard disk and your heart is also has of
cat
which is jib disc disc pack Winchester
days and your optical disc also has some
categories which comes in CD ROMs whoa
cd-rw and DVD and your memory storage
device has to also categories which is
flash drive which is also called pan
drive you are people use pan drive it is
also come in this flash drive and memory
card in your phone in your digital
camera all of them in there as a memory
card attached ok so this comes here we
will learn about all these devices in
our next lectures so now we are going to
our first which is device called
sequential access device so now we came
here see what is sequential as name
suggests in sequential access device
data will be access in a sequence how
look this is just a reason that this is
your memory your data is divided into
say first one data is stored here second
is their third world for one here and so
on okay so if I want to this is a first
data this is a second data third and so
on okay I want to access this one data
then I will easily get it but I want to
search up fifth Oh sis data then I count
these there this sixth one data directly
I will be cool like that in a sequential
first 2 3 4 5 6 and then I will come
here so this is the pattern to access
any data from the sequential access
device so first point ever is arrival at
the desired Astoria location may be
preceded by sequencing through other
location I already told you that how you
how you get your data restore your data
in a sequential okay
suppose if you fill up this four area
and involve you want to enter any data
then where it will we go it will be go
there next data rate of data will be go
they are same here data will be access
in a sequential way okay next point data
can only be retrieved in the same
sequence I already told you with example
that data can be retrieved
little metal of excess okay what is the
meaning of retrieve excess you can the
data can only be retrieved in the same
sequence in which it is stored okay
suppose of aapke data happens two or
three he is any Clara snea Kop Hasani
car organism in Congress or possibly
next point excess time varies various
means differ okay Malachy Bedell
tourette ahead your excess time differ
differ or varies according to the
storage location means I already told
you in my previous one lecture that what
is the excess time the time to access
our data from the memory is called the
excess time so the X stands very how
suppose I want to access the by first
data then I will take take that one data
in a very quick short may be in a second
but my data is is stored here then
definitely I already told you that that
it is go like that so if it is take of
one nanosecond then it will increase or
maybe it will take around six
nanoseconds okay so that excess time
where is according to that storage
location where it is located
it will depend on that only okay of the
information being accessed okay next
point suitable for sequential processing
where it is suitable where you need to
exit data in a sequential with which
kind of application you can imagine
suppose I want to make
a salary pay slip of my implies it is
obvious that I want to give a salary to
my um price and I in my company there
are hundred employees so I definitely
give all of them it is not possible
mother I am going giving only salary to
my 50 employees and not to others not
possible okay so here processing will be
done to each and every employee so here
I can do my sequential Excel I can use
my sequential access a device because
every s employ data I want that how many
leads that one imply take it ok how many
extra time or overtime he had done I
want all information these kind of all
information from my each and every
employee so here here I can say that
that I want a sequential access because
I knew not want to know each and every
employee status leaves change status or
overtime which he had done ok or if he
had take some half leave some like that
so same thing like that I want each and
ever and we imply from my company so I
will take the sequential access storage
device for this purpose if not all of
data records need to be processed one
after anyway what is me that I want to
process data forces on data one after
another okay magnetic tape we will going
to learn about know about what is the
magnetic tape in our next slice but yeah
and here is another magnetic tape is a
typical example of such a storage device
okay so the example of storage this kind
of storage devices magnetic tape now
here we came into magnetic we already
seen in our diagram please make that
Venn diagram so you will be memorize it
okay in
in your sequential access the storage
device there is only one device scale
which is called magnetic tape you all
people see magnetic tape in your
childhood okay or you can say in your if
you go to previous a last term 14 or 15
you're back that you all have seen this
kind of audio cassette or video can see
these called
a magnet tip okay now we came here first
point about magnetic tape what it is
commonly use sequential access device if
you use these kind of audio castles of
video cassette then you have been very
much familiar that this is the first
example where you can say that it is the
main example of sequential restores us
because they are data games in a
sequential ways suppose if you want to
listen a song so then the first song
which is stored in here will become
first than the second one than the third
word if you want to listen a third one
data that have all how do you do it you
just forward your Cassatt and then you
reach to your second third one song and
listen to it but you can't directly
listen that one song okay so this is the
main example of your magnitude tape so
it is a commonly used sequential access
storage device physically the tape
medium is elastic ribbon if you see in
your audio cassettes
so you can directly know that that it
has a ribbon which is made by plastic
which is usually half inch 1/4 inch wide
and 50 to 2400 feet long
next point is plastic ribbon is coated
with a magnetizable please note down
that your plastic ribbon is coated with
magnetizable recording materials such as
and what is that
recording material it is iron iron my
oxide on chromium dioxide okay data are
recorded on the tape in the form of tiny
what is tiny
Kangnam is very small very small
invisible which we can't see okay
so small or very small invisible spot
which are may made on your tape you
cannot see by your eyes okay but if you
see to a magnifier then you definitely
be able to see it data are recorded on
the tape in the form of tiny invisible
magnetized or non-magnetized spot
representing once and zero on its coated
surface okay so the data how data is
told through a magnetized ever recording
material somewhere it is like this is
your tape so how it is show some data
astoria so you have magnetizable in case
will be spare hell if here then here
like that but you can see it by your
eyes okay
now the next point is tape ribbon is
stored in trees where it is a store you
can see in the picture that tape ribbon
is the store in a wreath or a small
cartridge or casts it you can see that
here this reel is stored in a real or
you can see this this is stored in a
castle okay now how many types of magnet
it is available half inch half inch tape
cartridge 1/4 inch streamer tape and 4
mm digital audio tape which is also
called dat okay write down the full form
of dat digital audio tape this all
points are very important for you if
social arise that find out how the type
which is not passed to your vanity
variable if you know these four time
then you will also that if suppose 5mm
option come then this is the odd one
then you will definitely select this one
that this is not possible in magnetic
tape okay now we came here advantages of
our magnetic tip what is the advantages
now we are going to see it first one is
storage capacity is what sure I already
told you why so if I need to store data
about my information that I will make
another CD make another tape okay so the
storage capacity virtually get unlimited
okay because as many as tab as required
can be used for story very large sets I
already explained you next point cost
per bit of storage is very low I if you
remember your audio cassette or video
cases comes in a very cheap able price
twenty to forty rupees
okay so this is the so cheap price so it
you can say that cost per bit of storage
is very low for magnetic tape tapes can
be erased your tape can be erased and
reused many times if you use any audio
castle so you will be you can remember
that that your you can record anything
on your magnetic tape again and again
you can it is the data which it had also
so is easing or reusing also possible in
magnetic tape next point next advantage
T freeze and cartridge are compact
compact myths small in size and lighting
width so you can easily carry it videos
okay next advantage easy to handle
because it is very compact and lighting
wear it so you can easily handle and
store it anywhere okay it is not so much
large in size if you have a small
expensive
you can also store it okay next
advantages very large amount of data can
be stored in smallest storage space okay
third next compact size and lightweight
next advantage magnetic tape prints and
cartridges are also easily portable from
one place to another if you want to take
your magnetic trip from one place to
another it is also easy because it is
light in weight you can hand it it onto
your hand and go to somewhere else and
put it up there okay next point often
use for transferring data and program
from one computer to another that are
not linked together if you have a two
computers that are not linked together
we just go through out here magnetic
tapes on the one computer and take it to
the souther computer and insert that
magnetic tape wind up into that computer
and it will work on it okay so how the
in this way you will link your two
computers ok limitation what is the
limitation first one is due to this
equation access nature they are not
suitable for a storage of those data
that are frequently required to be
accessed ramen randomly there are some
data if you want it many times to for
processing okay and if you store it in a
sequential then I already told you that
the access time is slower so definitely
it will slow down your processing speed
this is the main limitation to speed of
your processor speed if you store your
data in your sequential storage device
which is magnetic tip then it will be
not good example okay and you need that
data again and again for your processing
okay now next limitation first one is
must be stored in a dust-free
environment your chip must be stored in
a dust-free environment because the
specs of
juice packs character space means Juke
just click on what they have walk out of
the Ark a magnetic tape may love cotton
jiske karen kavett ahead reading error
as a TA because of it
magnetic tape get corrupted okay next
limitation must be stored and an
environment with properly controlled
temperature because you know that your
magnetic a made by the book which is in
flower which is the plastic okay and if
the pressure is very high what will can
happen here plastic tape the processes
even will become meshed okay so it is
your responsibility to keep it top space
place where temperature is not too high
okay and humidity if a humidity area
will be there then what will be your
magnetic tape will be cat damage which
if a jacket as well okay tape ribbon may
get twisted due to wear pink okay
sometimes if you see in your audio
Cassatt what happened your magnetic tape
get twisted it is not like that okay so
this is the main limitations resulting
in loss of a store data the next
limitation is should be properly labeled
so that some useful data is stored on a
particular tape is not areas by mistake
you must label your magnetic tape
otherwise what will happen whatever the
data it has because it is not from if
you want not permanent always because
whenever you the ear is it it will be
raised okay so label it properly way so
that are useful data never be get erased
by mistake okay what is the use of
magnetic tape first one for application
that are based on sequential data
processing I already told you like
employee payroll you are preparing then
here you will use it next one
backing above data the data we want to
back up okay
for offline storage what is offline and
online online means like be your banking
system it is all online okay here you
want a data you to bother something some
rupees in your account okay then it will
be automatically updated at that time -
okay in your account system also and you
can anyone can see this okay this is
called the online wave or story they are
depositing it and it after that you are
account updated it so this is called
online storage next point is our
chipping of infrequently used data you
can our chip our chip means you know now
that raw data Joe up some hollaback
Marrakech Artemis Cabana of the economy
turning gay whose carbonate arch is
curlier hair or leg info data you are
not using that one data very frequently
and but you need it then you will our
change that data in your magnetic tape
next point TAS transferring of data from
one computer to another computer that
are not linked together we already
discuss about this point this is the use
of magnetic tape now here your magnetic
tape and sequentially excess device part
is kept random now we came here the
direct exercise what is the meaning of
direct access device it means in
sequential access data this is your
memory okay
and your data is here I have told you
about this then you want to access the
user data in sequential is like that but
indirect Texas if you want this one data
you will directly access that word but
data you need not to go like that okay
you can directly access
data this is called a director storage
device okay now we came here device is
there any storage location may be
selected you can select any location
memory location and exists at randomly
randomly what does it mean a he say B
omnicaster K hey apply data next point
permits access to individual information
in a more direct or immediate manner it
means that it permits access to
individual information any individual
information you can access directly and
immediately de dieu will no it will not
take a dime whatever a time to access
this one data will be same to access
that friend data also okay next point
approximately equal access time is
required I already told you before that
whatever the time it clicks is this one
data will be similar to access that one
data also okay for accessing information
from any storage location next point so
J well for direct processing application
such as online ticket booking system and
online banking now you get to know that
what is offline and online all this kind
of things are online basis ok online
ticket booking system online backing
system this is all for here on
application we use cherry Texas storage
devices ok next use magnetic optical
magneto-optical days a typical example
of such storage device we will learn all
about it but here if this is the example
you can note down that magnetic optical
and magnetic optical disk are the
typical example of Direct Taxes device
first if you see in my diagram then
there is a first one is magnetic disk ok
now we are going to avoid an aggregate
is you know all that how is magnet it is
it is a
all labeled is okay this is called your
magnetic this okay commonly use direct
access a continuous device next
characteristic physically our magnetic
disk is a thin it is a thin circular
plate or platter made of matter it is
made by metal or plastic you can say
that it can be in plastic material that
is usually coated on both side coating
is in the both side this is not a 3d
view so you can say but you if you see
in there magnitude is it is quoted from
both the side with a magnet is equal
type n magnet is I arrow magnetizable
recording material right down it that
units quote is with which material
magnetized ever recording but area such
as iron oxide okay next point is data
are recorded on the disk in the form of
tiny invisible I already told you about
tiny very small invisible that tears
sports which are we cannot see is call
invisible magnetized and non-magnetized
spot representing one side 0 okay means
see this type of coating is will be done
to your disk to tiny invisible
magnetized or non-magnetized spots okay
on the cottage surface of the disk next
point that this is stored in a specially
designed protective envelope or
cartridge if you see in your focus on
anything else your disc is inserted here
and it is covered too in a cartridge Ora
and lift okay so basically you can't
hold it directly it is will be in a
cover it will come in a cover so disc is
stored in a special design protective
and block or cartridge your heart is
also coming a magnet it is okay so all
these thing you can't handle it by your
own
okay it is in a protective cover or
several of them are stacked together you
can say that in a cover there is a
process
they recover there are so many when the
teachers are here and these are sealed
covered together sale in a contamination
free container okay this is the basic
organization of your discs you can see
this that your disc is divided like that
this area this area like it this one see
like is Percy in the video that this
area which I am parking this is called
whole track okay this is your one two
three
my teachers normally started from your
inner okay if this is a little zero one
two three four five and so on okay so
this called your track and each track is
divided into sectors this length called
sector
well you just assume that this is a zero
sector this is a one two three four five
six and seven so you can see that in
example there are five side tracks and
seven sector okay this is the basic
organization which is you can read it
here that a disservice is divided into a
number of invisible you cannot see but
it is divided into invisible concentric
circle circles for track I already seen
do that all this thing is called track
okay
after that the track are numbered
consecutively from outermost to
innermost starting from zero okay next
is each track of disk is subdivided your
East rackets are divided into sector and
there are eight or more sector for track
okay atlases or eight sector or it will
be more and next is a sector typically
contains how many bytes 112 wide ok so I
512 512 bytes okay next point is this
driver are designed to read or write in
all your computer there is a driver
which is called dis driver
so this driver are designed to read or
write only the whole sector at a time it
can read only one sector this is your
car once act enough this is your one
sector okay so all this sector will be
read by you a disk driver okay I already
told you that your you have so many
disks also in our sale packed container
here you can see that there is a four
discs are having in our one package ok
same like that now we are going to know
that what is the extent this access time
is the interval between that instant a
computer makes a request for transfer of
data from our disk system to the primary
storage and the stalls this operation is
completed ok exists and keahak eb kitten
a time a chaos a letter hey excess kind
ma or whoa aki requests we take a pod
iterator that that is called a excess
time now this SS time depends on the
following 3 XS y axis time is dependent
three parameters which is fake time
latency time and transfer rate first of
all we are going to see that what is
seektech it is that I am required to
position the rear or right head this is
if your figure you can see that this is
I this is black pointers are added okay
this will rotate in your CD and will
find out the data if our data is not in
that CD then the data header will be
moved to Durban City and will try to
read and either data from this and if
their data is also not present here then
it will go there then it will go there
so so what is the seek time see time is
the time required to position your
rewrite right head this is a read/write
head to position it over the desire
try to come over to live this is your
bisque okay and so many tracks over
there
if your track is here and your data is
here so to make goes their header here
it is called your seek time okay as well
so as soon as a read/write command is
received by the disk unit next year that
latency time what is the latency time it
is the time required to spin the desired
sector under the read/write head c10
what is to reach to the desired track
and what is the seek latency time you
reach to the desire track but you are
not at the desired sector up Emilie's
desire fact where the pause go ahead
thinking of your a desired sector where
when you watch your hair then it will be
spin in that one track this is the corn
Lee density when your readwrite head
will go to the desired track so I sector
then the time it will take it this is
called the latency time once the
read/write head is position on the
desire track okay transfer rate what is
the transfer rate it is a rate it is the
rate at which data are read or written
to the disk
once the read or write head is position
over the head how much data will be
transferring from secondary to your
screen or your output device this is
called the transfer rate if it takes 18
KB per second it means 80 Kevin it T KB
data is transferring from the secondary
storage device to your primary or
somewhere is this is called the transfer
rate so here we end up the our lecture
here what we have seen secondary memory
in secondary memory what we have learnt
that secondary memory is divided into
sequential access a direct access and
indirect Texas directors
has only magnitude disk which is a
magnetic tape which we have read it or
learn it and we also get to know that
what is the direct access devices and in
directed the access devices we learn
about the magnitude what is the
magnitude is and their structure okay
now in our next lecture we will get to
know the subcategories there are three
tacit degrees magnetic disk optical disk
and your memory Nexus devices okay we
will see all these topics in our next
lecture so people here we are going to
end up and if you like my video then
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mcq on your computer fundamental topic
but first of all I want to clear all
your whole set after that I will make it
for you till then please try to listen
all my this or see all my these videos
because if you get thoroughly to my this
video then you will be definitely able
to give any kind of memory related
question which will come to your push
exams so it will be better to go through
the entire topic thoroughly only then
you will be able to give any answer any
questions also okay so till then take
care guys have a nice day