20-Mass_Storage_IO_II_2spp

20-Mass_Storage_IO_II_2spp - CSE 421/521 - Operating...

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Unformatted text preview: CSE 421/521 - Operating Systems Fall 2011 Lecture - XX Mass Storage & IO - II Tevfik Koşar University at Buffalo November 10th, 2011 1 RAID Structure • As disks get cheaper, adding multiple disks to the same system provides increased storage space, as well as increased reliability and performance. • RAID: Redundant Array of Inexpensive Disks – multiple disk drives provides reliability via redundancy. • RAID is arranged into six different levels. RAID (cont) • RAID schemes improve performance and improve the reliability of the storage system by storing redundant data. – Data Striping: splitting each bit (or block) of a file across multiple disks. – Mirroring (shadowing): duplicate each disk • Simplest but most expensive approach – Block interleaved parity uses much less redundancy. RAID Levels RAID Level 0 ! ! ! ! 5 RAID Level 0 - block level 6 RAID Level 1 ! ! ! ! ! 7 RAID Level 1 - block level 8 RAID Level 2 ! ! ! ! ! ! ! 9 RAID Level 2 - bit level 10 RAID Level 3 ! ! ! ! ! 11 RAID Level 3 - byte level 12 RAID Level 4 ! ! ! 13 RAID Level 4 - block level 14 RAID Level 5 ! ! ! ! ! ! 15 RAID Level 5 16 RAID Level 6 ! ! – more reliability versus less data space ! 17 RAID Level 6 18 RAID (0+1) and (1+0) ! ! 19 RAID (0+1) and (1+0) 20 RAID (0+1) and (1+0) RAID 0+1 RAID 1+0 21 Any Questions? Hmm. . 21 Acknowledgements • “Operating Systems Concepts” book and supplementary material by A. Silberschatz, P. Galvin and G. Gagne • “Operating Systems: Internals and Design Principles” book and supplementary material by W. Stallings • “Modern Operating Systems” book and supplementary material by A. Tanenbaum • R. Doursat and M. Yuksel from UNR 23 ...
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This document was uploaded on 11/12/2011.

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