File allocation methods are crucial for efficiently organizing and accessing data on secondary storage by dividing files into logical blocks and mapping them to physical disk sectors.
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Hello friends, Welcome to Gate Smashers
In this video I am going to explain allocation method
or you can call it as file allocation method
which is the most important point of the file allocation system
and this is important for your competitive exams
and very much important even for your college and university exams
because from this topic many questions come in exams
So guys quickly like this video and subscribe this channel
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So let's start
What is the actual purpose allocation method?
means the file system we have
What it does?
Let's say I have a file,
file name is F1
and on the other side what do we have? we have hard disk
that is your secondary storage
Now what we do? what actually the file system does?
It divides this file logically
in blocks.
Means before putting this file as it is in disk what it will do?
divide this file logically in to blocks
and on the other side the hard disk we have
or the permanent storage we have
what we have in that storage?
It has sectors.
Which you can call physical blocks.
means where the data actually resides
and what do we call them? Sectors
Although sectors are not like this
We have platters, on platter we have surfaces
on surface we have tracks
on tracks there are sectors in this way.
So here just I am showing you by visualizing simply
how the data is loaded on sectors.
So what the file system did? First it divided the data
divided the file and did logical partitions
and now what will it do with these blocks?
on these physical sectors
put it over these physical sectors of the disk
now see depending on how we put it
Where are we putting a particular block or block of a file
in what way we are putting, that is actually allocation method
So the allocation method can be contagious
or it can be non contagious
and in non contagious further we have two types
Linked list allocation
and indexed allocation
So there is a simple way to understand this.
Let's say we have a lot of students,
there are lot of students
Now what we did? On other side we have a room
and inside the room we have seats
there are vacant benches
Now what are we doing?
In actual what the file system is doing?
What we have to do now?
We have to take the students in to the room
We have to allocate bench to students inside the rooms,
that you sit on this bench, you sit on this bench,
what actually the file system is doing?
It is not like that we are sending students directly
What I did first? I divided the students in sections
means made sections like
section 1, section 2, section 3, section 4
and then what are we doing?
we are moving these sections into the rooms
So what we can call them inside the room?
One is contagious, what is the meaning of contagious?
that I will say roll no. 1 sit on bench no. 1
after that roll no. 2 on bench no. 2
3 on bench no. 3
in this way we will make contagious allocation
but this is not necessary that roll No. 1 on bench No. 1
you can also start roll No. 1 from bench No. 10
Let's say you said roll No. 1 go to bench No. 10
now where will roll No. 2 sit, he will sit on bench no. 11
where will 3 sit, sit on 12
means 13 then 14 means
you have to start contagiously but you can start from any place
So that is actually the contagious allocation.
similarly you can put randomly
said to roll No. 1 to go to bench no. 5
roll No. 2 go to bench No. 90
roll No. 3 go to bench No. 53
that is the random allocation
so based on our requirement
based on the scenario we do contagiously
and non contagiously also
so if someone ask you what is the purpose of allocation method?
What are we achieving from that?
So first thing we are achieving
efficient disk utilization
means the disk we have that we have to utilize properly
so what does this means to utilize properly
So disk has some capacity let's say 1 terabyte capacity
so that capacity I have to use properly or utilize in efficient way
it should not happen that there is some fragmentation effect
or external fragmentation is happening
or some blocks are not filled properly
meaning we want that we can utilize it properly
and second advantage that we are giving
is access
we are saying that the data we have to put on the disk
It does not mean that we will never access that data
Obviously what are you doing? In your laptop you store data daily.
sometime you download sometime you bring it in pen drive
you received from mail and downloaded from there
So through multiple ways you are collecting data
Now to collect that data
why are you obviously collecting it?
So that when you need you can access it.
means you can retrieve it
so access should be faster
So if we use allocation method properly
so the access I have should be faster
means access time should be less
then obviously you can say that
performance of the system will increase
because in less time you are trying to access more and more data
accessing more and more data in less time
so you can say access time should be less
or you can say like this also
that my access speed should be faster
So these are actually our two aim
of the allocation method
how to efficiently utilize disk space
and how to make access faster
so now in next video we will discuss
What is contagious allocation?
What are the advantages and disadvantage?
same way, what are the advantage and disadvantage in non contagious?
Thank You.
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