Sun Microsystems Virtual Tape Library Bedienungsanleitung PDF herunterladen (Seite 59)

Managing virtual libraries

96267 • G Chapter 4 VTL operations 45

Nexttask:

■ Ifyouaregoingtoconfig uretapecachingon thisvirtuallibrary,goto

“Configuring AutomatedTapeCaching”onpage 45.

■ Ifyouaregoingtousetheautomaticarchivingfeatur es,goto“Settingupthe

AutoArchivefeature”onpage 49.

■ Ifyouaregoingtousetheautomaticreplication feature, goto“Settingupthe

AutoReplicationoption”onpage 50

■ Otherwise,goto“Generatingthevirtuallibrary”onpage 51.

ConfiguringAutomatedTapeCaching

YouconfigureAutomatedTapeCachingforthevirtuallibraryby defininga

migrationpolicyand areclamationpolicy.AVTLpolicyissimplyasetofcriteria

(triggers)thatcontrolhowandwhenVTLsoftwareautomaticallymovesdatafrom

itsphysic al diskcache.Usingtheconfigurationdialogs,you ca n 

specifysimple

schedulesormorecomplexstate‐andevent‐drivenpolicies.

MigrationpoliciescontrolwhenVTLcopiesdatafromthediskcachetophysi cal 

tape.Goodmigrationpoliciesmaximizetheperformanceandreliabilityofthedisk

cachebyminimizingsimultaneousreadsandwrites.Simultaneousread s and 

writes—crossI/O—forcediskarraysto

switchbackandforthbetweenmultiple,

competingI/Oste am s,reducingthroughputandsubjectinghardwaretoexcessive

wear.Sobestpracticeistoschedulemigr ationassoonaspossibleafterabackup

ANDatatimewhenotherbackupjobsarenotrunning.

Reclamationpolice scontrolwhenVTLreleasesthediskspace

thatis usedbyadata

setthathasalreadymigratedtotape.Promptandefficientreclamationprevents

over‐subscriptionofthediskandconsequentbackupfailuresandsystemdowntime,

whileminimizinginvestmentincachecapac ity.Bestpracticeistoreclaimspaceas

soonasthehighest demandfor

restoreshaspassed—typicallyafterthreetofive

days.Thisapproachstrikesthebest balancebetweentakingadvantageofthespeed

andconvenienceofadisk‐basedrestoreandminimizingconsumptionof cache

space.

Tocreateamigrationpolicy,selectoneofthefollowingapproaches:

■ “Creatingsimp le schedule‐drivenmigrationpolici es” onpage 46

■ “Creatingstate ‐andevent‐basedmigrationpolicies”onpage 4 6.

Thengoto“Creatingareclamationpolicy”onpage 48.

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Sun Microsystems Virtual Tape Library Bedienungsanleitung Seite 59