REP-1995-163 - A na ly s iso ftheR equestP attern stotheN...

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Unformatted text preview: A na ly s iso ftheR equestP attern stotheN SSDCO n-lineA rch ive TheodoreJohn son ted@ c is .u .edu C ode D ep t .o fC IS NA SAG oddardSpaceF ligh tC en ter U n ivers ityo fF lor ida G reenbe ltMD G a inesv ille ,F l- A b stract NA SAm iss ion s ,both forearthsc ienceand forspacesc ience ,co llecthugeam oun ts o fdata ,andtherateatwh ichdata isbe inggathered isincreas ing .F orexam p le ,the EO SD ISp ro jectisexpectedtoco llectpetaby tesperyear .Inadd it ion ,thesearch ives arebe ingm adeava ilab letorem oteu sersovertheIn ternet .Theab ilitytom anagethe grow tho fthes izeandrequestact iv ityo fsc ien t icarch ivesdepend sonanunderstand ing o ftheo ftheaccesspattern so fsc ien t icu sers . TheN at iona lSpaceSc ienceD ataC en ter(N SSDC )o fNA SAG oddardSpaceF ligh t C en terhasrunthe iron-linem assstoragearch iveo fspacedata ,theN at iona lD ata A rch iveandD istr ibu t ionServ ice(NDAD S ) ,s inceN ovem ber .A largew or ld-w ide spaceresearchcomm un itym akesu seo fN SSDC ,request ingm orethan, lesper m on th .S incethein it iat iono fthe irserv ice ,theyhavem a in ta ined logleswh ichrecord a llaccessesthearch ive . Inth isreport ,w ep resen tanana ly s iso ftheNDAD S logles .W eana lyzethelog les ,andd iscu sssevera lissues ,inc lud ingcach ing ,re ferencepattern s ,c lu ster ing ,and sy stem load ing . In troduct ion O n-linesc ien t icarch ivesarean increas ing ly im portan ttoo lforperform ingdata-in ten s ive research .Bu ild inga large-sca learch iveisanexpen s ivep ropos it ion ,how ever ,andsy stem resou rcesneedtobecare fu llym anaged .T odate ,therehasbeen litt lepub lishedresearch thatstud iestheperform anceo fon-linesc ien t icarch ives . T heN at iona lSpaceSc ienceD ataC en ter(N SSDC )o fNA SAG oddardSpaceF ligh tC en- terhasrunthe iron-linem assstoragearch iveo fspacedata ,theN at iona lD ataA rch iveand D istr ibu t ionServ ice(NDAD S ) ,s inceN ovem ber . A largew or ld-w idespaceresearch comm un itym akesu seo fN SSDC ,request ingm orethan , lesin .S incethe in it iat iono fthe irserv ice ,theyhavem a in ta ined loglesw h ichrecorda llaccessestothe arch ive . Inth ispaper ,w ep resen tanana ly s iso faccesspattern stotheNDAD S .T heseana ly ses arebasedonthein form at ioncon ta ined inthelogles .W ed iscu sssevera laspectso fsy s- tem perform ance ,inc lud ingtheperform anceo fsevera lcach inga lgor ithm sontherecorded requeststream ,andtheeect ivenesso fthedatac lu ster ingu sedbyNDAD S .W eshow that therequestforalearebu rsty ,andthatu serrequestsarebu rsty .F ina lly ,w ep resen tan ana ly s iso fthesy stem load . Severa lstud iesonthere ferencepattern stom assstoragesy stem shavebeenpub lished . Sm ith ana lyzeslem igrat ionpattern sinh ierarch ica lstoragem anagem en tsy stem . T h isana ly s isw asu sedtodes ignsevera lH SM cach inga lgor ithm s.Law r ie ,R anda l,and Bu rton com paretheperform anceo fsevera llecach inga lgor ithm s .M illerandK atz T h isw orkw asperform edw h ileT heodoreJohn sonw asanA SEESumm...
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This note was uploaded on 01/22/2012 for the course COP 5555 taught by Professor Staff during the Fall '08 term at University of Florida.

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REP-1995-163 - A na ly s iso ftheR equestP attern stotheN...

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