Asalamualik um My Name Is Raza Umer.BSCS Section 1A Roll No. 1027
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.
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.
Disk array.A disk array is a disk storage system which contains multiple disk drives.A disk array is commonly known as a RAID (RedundantArray of Inexpensive disk) .As a secondary storage device, provides enhancedStorage capacity, enhanced performance and enhancedreliability.Enhanced storage capacity is achieved by using multipledisks.Enhanced performance is achieved by using parallel datatransfer technique from multiple disks.Enhanced reliability is achieved by using techniques suchas mirroring or striping.
In mirroring, the system makes exact copies of files on two harddisksIn striping, a file is partitioned into smaller parts and different parts ofthe file are stored on diffetent disks. A RAID Unit
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.
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
Storage Hierarchy. CacheSmaller capacity, memoryfaster Main memory Large capacityAccess time, and On-line, direct access and Slower access timehigher Sequential-acces secondory And lower cost perCost 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.
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