- Sun Storage Virtual Tape Library VTL User Guide

Managing virtual libraries

40 VTL User Guide • May 2008 G • 96267

boththeneededlong‐termstoragecapacityandthefaste stpossibletransfertotape

media.Compressionhardwarecannotfurthercompressdatathat has been

compressedbysoftware,sotheend‐to‐endbackupprocessissignificantlyslower.

Ontheotherhand,theVTL softwarecompressionfeatureis valuablewhenitis

truly

needed:

■ whendataisstoredontheappliancelong‐term,ratherthancac he d pending

migrationtolong‐termstorageon physicaltape

■ whendatahastobereplicatedacrossaslowWANlink.

3. Ifyouplantousetapecaching,usethespinnercontroltoadjusttheTape

Caching Policy Disk Capacity Thresholdto85%(

D above).

Whenusing automatictapecaching,youhavetomakesurethatthediskneverfills

up,preventingyoufromcreatingnewvirtualvolumes.The75%thresholdhasbeen

foundtoofferagoodmargin ofsafety.

4. PressOK(

E above) .

Stophere.