- Sun Storage Virtual Tape Library VTL User Guide
Managing virtual libraries
96267 • G Chapter 4 VTL operations 85
VTLsupportstwotypesofcompression:
■ Hardwarecompression‐usesaHifnExpressDR1000(1GB/seccompression)or
DR600(600MB/sec)compressioncard.Alicense keycodeisrequiredfor
hardwarecompression.
■ Softwarecom pre ssi on‐usesanLZOalgorithmthatrunsontheVTLserver.
Inordertousecompre ssi on, youmustalsoenabletapedrivecompressi on inyour
backupapplication.
Note – Note:Ifyouarealready usingsoftwarecompressionthatissuppliedbyyour
backupapplication,youshouldnotuseVTL’scompression.Usingbothtypesof
compressionwillcau s eVTLtotrytocompressalready‐com pre ssed dataandthis
canslowdownyourbackups.
▼ To enableor disablecompression:
1. Enabl etapedrivecompressioninyourbackupappl icat ion.
2. Ifyouareusingh ardwarecompression,installacertifiedcompressioncardin
yourVTLserver.
YoucanhaveuptotwocompressioncardsperVTLserver.
Thecompressioncard(s)mustbeinstalledbeforecompressionbegins.Ifyoutryto
usehardwarecompression an da
compressioncardisnotavailable,VTLwillsend
anerrormessagetotheconsoleeventloganduncompr esseddatawillbewrittento
thevirtualtape drive.
3. IntheVTLConsole, right‐cl ick onVirtualT apeLibrarySystemandselect
Properties.
4. SelecttheEnableVirtualT apeLib rarycompressionmodecheckboxand
specifywhetheryouare
usingSoftwareorHardwarecompression.
IfyouareupgradingaVTLsystemthatpreviouslyusedsoftwarecompressionto
nowusehardwarecompression,thecompressi o nmodewillbeswitchedto
hardwarewhenthetapeisoverwritten.
Bothtypesofcompressionareglobalsetti ng s, whichmeansthattheywillapplyto
alltapes
inyoursystem.
IfcompressionisenabledontheVTLse rver,youcanstilldisableorenable
compressiononeachindivid ual virtualtapedriveinthesa me mannerasrealtape
drives‐‐viayourbackupapplicationorviaSCSIcommandswhicharesentbythe
operatingsystem.