2. Asalamualik
um
My Name Is Raza Umer.
BSCS Section 1A Roll No. 1027

3. Mass Storage Devices.
 Mass storage device are storage system having storage
capacity of several trillions of bytes of data.
 They use multiple units of a storage media (such as
multiple disks, multiple tapes, multiple CD-ROMs,
etc.) as a single storage devices.

4.  Disk array using a set of megnetic disk.
 Automated tape library using a set of megnetic
tapes
 CD-ROM jukebox using a set of CD-ROMs.

5. Disk array.
A disk array is a disk storage system which contains multiple disk drives.
A disk array is commonly known as a RAID (Redundant
Array of Inexpensive disk) .
As a secondary storage device, provides enhanced
Storage capacity, enhanced performance and enhanced
reliability.
Enhanced storage capacity is achieved by using multiple
disks.
Enhanced performance is achieved by using parallel data
transfer technique from multiple disks.
Enhanced reliability is achieved by using techniques such
as mirroring or striping.

6.  In mirroring, the system makes exact copies of files on two hard
disks
In striping, a file is partitioned into smaller parts and different parts of
the file are stored on diffetent disks.
A RAID Unit

7. a) Set of magnetic tapes and magnetic tape drives with a controller
mounted in a single box, forming a single large storage unit.
b) Large tape library can accommodate up to several hundred
high capacity magnetic tapes bringing the storage capacity of
the storage unit to several terabytes.
c) Typically used for data archiving and as on-line data back up
devices for automated back up in large computer centers.
Automated Tape Library.

8. a) Set of CD-ROMs and CD-ROMs drives with a controller
mounted in a single box, forming a single large storage unit.
b) Large CD-Rom jukebox can accommodate up to several hundred
CD-ROM disks bringing the storage capacity of
the storage unit to several terabytes.
c) Used for archiving read-only data in such applications as on-line
museums, on-line digital libraries, on-line encyclopedia, etc

9. Storage Hierarchy.
Cache
Smaller capacity, memory
faster Main
memory Large capacity
Access time, and
On-line, direct access and Slower access time
higher
Sequential-acces secondory And lower cost per
Cost per bit stored
Storage devices such as hard disk Bit stored
Off-line direct access and sequential
Access secondary storage devices such as
Tape, floppy disk,zip disk etc.
Mass storage devices such as tape library, CD jukebox, etc.