1CSC 4103 - Operating SystemsFall 2009Tevfik Ko!arLouisiana State UniversityNovember 12th, 2009Lecture - XXIIMass Storage and I/O - IIRAID 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 LevelsRAID Level 05!!"#"$%&$'%(%')'$%*#+$,-+./&$"*'$%&$&01)"'$%*$"$2%3)'$+1')1$"4+*5$"--$#6)$'%&/&$%*$#6)$"11"7!'+)&$*+#$01+(%')$"*7$2"8-#$#+-)1"*.)!"-&+$/*+9*$"&$'%&/$%0%*5!%401+()&$1)"'$"*'$91%#)$0)12+14"*.)$(%"$0"1"--)-$"..)&&RAID Level 0 - block level6RAID Level 1!:--$'"#"$91%##)*$#+$#6)$01%4"17$'%&/$%&$91%##)*$#+$#6)$4%11+1$'%&/!01+(%')&$"$1)'8*'"*#;$%')*#%."-$.+07$+2$"--$'"#"!01+(%')&$2"8-#$#+-)1"*.)!"-&+$/*+9*$"&$'%&/$4%11+1%*5$!"-&+$5)*)1"--7$%401+()&$1)"'$0)12+14"*.)$<,8#$4"7$')51"')$91%#)$0)12+14"*.)=> 7RAID Level 1 - block level8RAID Level 2!8&)&$4)4+17?-)$)11+1$.+11).#%*5$.+')$<@AA=$#6"#$)40-+7&$'%&/?%0%*5$"#)57$#6"#$,1)"/&$"$2%-)$%*#+$,%#&$"*'$&01)"'&$%#$".1+&&$48-#%0-)$'%&/&!B6)$)11+1?.+11).#%+*$4)#6+'$1)C8%1)&$#61))$)3#1"$'%&/&$2+1$2+81$'"#"$'%&/&!01+(%')&$2"8-#$#+-)1"*.)$<D"44%*5$A+')$EF;GH=!."*$,+#6$')#).#$I$1).+()1$21+4$&%*5-)$,%#$2"%-81)&!."*$')#).#$,8#$*+#$.+11).#$'+8,-)$,%#$2"%-81)&!,8#$%&$*+#$"&$)22%.%)*#$"&$+#6)1$J:K!$-)()-&!L+9;$"--$'%&/&$6"()$&%4%-"1$)11+1$.+11).#%+*$.+')9RAID Level 2 - bit level10RAID Level 3!&%4%-"1$#+$J:K!$-)()-$M;$,8#$%#$1)C8%1)&$+*-7$+*)$'%&/$2+1$0"1%#7$2+1$N$'"#"$'%&/&!,7#)?-)()-$%0%*5!&822)1&$21+4$"$91%#)$,+##-)*)./;$,)."8&)$"--$0"1%#7$'"#"$%&$91%##)*$#+$"$&%*5-)$'1%()!,8#$01+(%')&$&+4)$1)"'$"*'$91%#)$0)12+14"*.)$%401+()4)*#>!J:K!$M$I$G$."**+#$&)1()$48-#%0-)$1)C8)&#&$&%48-#"*)+8&-7$11RAID Level 3 - byte level12RAID Level 4!O%4%-"1$#+$J:K!$-)()-$G;$,8#$%#$)40-+7&$%0)'$'"#"$%*$48.6$-"15)1$,-+./&$+1$&)54)*#&!L+#$"&$)22%.%)*#$"&$J:K!$-)()-$P;$,)."8&)$<"&$%*$J:K!$-)()-$G=$"--$0"1%#7$'"#"$%&$91%##)*$#+$"$&%*5-)$'1%()!J:K!$-)()-$N$&822)1&$21+4$"$91%#)$,+##-)*)./$<'8)$#+$0"1%#7$'%&/=$"*'$%&$*+#$5)*)1"--7$8&)'>$13RAID Level 4 - block level14RAID Level 5!/*+9*$"&$%0%*5$9%#6$0"1%#7!#6)$4+&#$0+08-"1$J:K!$-)()-;$1)0-".)'$J:K!$G$I$N!&%4%-"1$#+$-)()-$N$%*$#6"#$%#$%0)&$#6)$'"#"$%*$-"15)$,-+./&$".1+&&$"--$#6)$'%&/&$%*$#6)$"11"7!K#$'%22)1&$%*$#6"#$%#$91%#)&$#6)$0"1%#7$".1+&&$"--$#6)$'%&/&!B6)$'"#"$1)'8*'"*.7$%&$01+(%')'$,7$#6)$0"1%#7$%*2+14"#%+*!B6)$'"#"$"*'$0"1%#7$%*2+14"#%+*$"1)$"11"*5)'$+*$#6)$'%&/$"11"7$&+$#6"#$#6)$#9+$"1)$"-9"7&$+*$'%22)1)*#$'%&/&15RAID Level 516RAID Level 6!&#+1)&$)3#1"$1)'8*'"*#$%*2+$#+$1).+()1$21+4$48-#%0-)$'%&/$2"%-81)&!9+8-'$*))'$M$"''%#%+*"-$'%&/&$2+1$)".6$N$'"#"$'%&/&– more reliability versus less data space!8&)&$J))'?O+-+4+*$)11+1$.+11).#%*5$.+')17RAID Level 618RAID (0+1) and (1+0)!A+4,%*"#%+*$+2$J:K!$Q$I$R!,)##)1$0)12+14"*.)$I$1)-%",%-%#7;$,8#$'+8,-)&$#6)$'%&/$&#+1"5)$1)C8%1)4)*#19RAID (0+1) and (1+0)20RAID (0+1) and (1+0)21RAID 1+0RAID 0+121Any Questions?Hmm..23Acknowledgements• “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
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