disk scheduling and disk management

1. Disk scheduling & Disk
management
By
k.Sivapriya
Msc(IT)
Nadar Saraswathi College Of Aarts and Science
Theni

2. concept
Disk scheduling
 Important of disk scheduling
 Seek time
 Rotational Latency
 Transfer time
 Disk Access Time
 Disk Response Time
 Purpose of disk scheduling
Disk management
Disk management availability
How to use disk management
More information on disk management

3. Disk Scheduling
Disk scheduling is done by operating
systems to schedule I/O requests arriving
for the disk. Disk scheduling is also
known as I/O scheduling.

4. Important of disk scheduling
 Multiple I/O requests may arrive by different
processes and only one I/O request can be
served at a time by the disk controller. Thus
other I/O requests need to wait in the waiting
queue and need to be scheduled.
 Two or more request may be far from each
other so can result in greater disk arm
movement.
 Hard drives are one of the slowest parts of
the computer system and thus need to be
accessed in an efficient manner.

5. Seek Time
Seek time is the time taken to locate the
disk arm to a specified track where the
data is to be read or write. So the disk
scheduling algorithm that gives minimum
average seek time is better.

6. Rotational Latency
Rotational Latency is the time taken by the
desired sector of disk to rotate into a
position so that it can access the
read/write heads. So the disk scheduling
algorithm that gives minimum rotational
latency is better.

7. Transfer Time
Transfer time is the time to transfer the data.
It depends on the rotating speed of the
disk and number of bytes to be
transferred.

8. Disk Access Time
Disk Access Time is:
Disk Access Time = Seek Time +
Rotational Latency + Transfer Time

9. Disk Response Time
Response Time is the average of time spent
by a request waiting to perform its I/O
operation. Average Response time is the
response time of the all requests. Variance
Response Time is measure of how
individual request are serviced with
respect to average response time. So the
disk scheduling algorithm that gives
minimum variance response time is better.

10. Purpose of Disk Scheduling
The main purpose of disk scheduling
algorithm is to select a disk request from
the queue of IO requests and decide the
schedule when this request will be
processed.

11. Disk management
 Disk Management is an extension of the
Microsoft Management Console that
allows full management of the disk-based
hardware recognized by Windows.
 Disk Management is used to manage the
drives installed in a computer like hard
disk drives (internal and external), optical
disk drives, and flash drives . It can be
used to partition drives, format drives,
assign drive letters, and much more.

12. Disk Management Availability
Disk Management is available in most
versions of Microsoft Windows
including Windows 10, Windows 8,
Windows 7, Windows Vista, Windows XP
and Windows 2000.

13. How to Use Disk Management
Disk Management has two main sections a
top and a bottom:
 The top section of Disk Management
contains a list of all the partitions,
formatted or not, that Windows
recognizes.
 The bottom section of Disk Management
contains a graphical representation of the
physical drives installed in the computer.

14. More Information on Disk
Management
 The Disk Management tool has a
graphical interface like a regular
program and is similar in function to
the command line utility diskpart, which
was a replacement of an earlier utility
called fdisk.

15. Cont…
 You can also use Disk Management to
check free hard device space. Look under
the Capacity and Free Space columns (in
the Disk List or Volume List view) to see
the total storage capacity of all the disks
as well as how much free space is
remaining, which is expressed in units
(i.e. MB and GB) as well as a percentage.

16. Cont…
 Disk Management is where you can create
and attach virtual hard disk files in
Windows 10 and Windows 8. These are
single files that act as hard drives, which
means you can store them on your main
hard drive or in other places like external
hard drives.