Sun Microsystems Virtual Tape Library Manuel d'utilisateur télécharger pdf (Page 15)

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CHAPTER

Introduction:VTLappliancesand

enterprisedata‐protection

SunStorageTekVirtualTapeLibrary(VTL)technologymakesthebenefitsofdisk‐to‐

disk‐to‐tapearchitectureavailabletocomplex backupenvironmentsthatcannot 

readilyaccommodatethedisruptionsandadministrativeburdensthatoften

accompanymajorchangestoinformation‐managementenvironm entsandprocesses.

VTLsol uti ons makediskmediaavailabletoapplicationsthatare

configuredtowork

withtape.VTLsoftwarepresentsyourexistingtape‐centricbackuparchitecturewith

whatappeartobe familiar tapelibra rie s, drives,anddatacartridgeswhilemanaging

thecomplexitiesoftheimplementation—diskarrays,RAIDgroups,andlogical

volumes—internally.

Suchtransparencyisa bso lutely criticalwhenbackupisjustoneaspect

ofan

enterprise‐widebusiness‐continuityplan.Whenlegacysystemsand multiple,

interdependentapplications,procedures,policies,and/orserviceprovider sare

involved,evenmodestchangestoabackuparchitecturecan haveunforeseen,far‐

reachingconsequences.

Theadvantagesthatdisk‐to‐diskbackuphastoofferarenolesscriticalincomplex

environments.

Heavyworkloads,tightschedules,andmultipledependenciesoften

makebackupwindowsverytightornon‐existent.Jobsthatfailto completecannot,

inmostcases,beretried.Tape‐basedbackupsystemsperformwellwhenhandling

bigjobs,likefullbackupsoflargefilesandfilesystemsthat canstreamlarge

amountsofsequentialdata.Butmuchofthe currentbackupworkloadconsistsof

intermittent,essentiall y randomI/O—incrementals,fullbackupsofheterogeneous

smallserversandworkstations,andsmallfiles(suchas thoseassociatedwithemail

systems).Tapedrivesperformpoorlyundertheseconditions.Butdisk‐basedstorage

isideallyplacedtohandle

thistypeofI/O.

Theremainderofthischapterprovides:

■ abriefsummaryofVTL“Features”onpage 2

■ adetaileddiscussionofthe“A d v a n t a g e s ofVTLtapevirtualization”onpage 4

■ amorein‐depthlookatselected,“KeyVTLfeaturesandoptions”onpage 8.

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