Spectra T50e - Connection Guidelines

Chapter 2—Installing the Library Installing the Tape Drives
August 2017 User Guide—Spectra T50e Library
58
Connecting SAS or SCSI Drives
InaSASorSCSIenvironment,eachdriveisconnecteddirectlyto
individualSASorSCSIportsonanHBAinthehost.Youcanalsoconnect
theSASdrivestoaSASexpandertoconnectthedrivestomultiplehosts.
Connection Guidelines
Thefollowingtableprovidesguidelinestokeepinmindasyouplanyour
connectionstoeitherSASorSCSIdrives.
Interface Connection Guidelines
SAS  Donotexceedbuslengthrestrictions.Themaximumallowablelengthofa
SASbusis13feet(4m).
 HBAtype.Useastandard6Gb/secondSASHBA.
 RAIDcontrollers.DonotuseaSASRAIDcontrollerwiththelibraryor
drives.
SCSI  DonotexceedSCSIbuslengthrestrictions.Themaximumallowablelength
ofanLVDSCSIbusis39feet(12m).
 RAIDcontrollers.DonotuseaSCSIRAIDcontrollerwiththelibraryor
drives.
 Daisy‐chainingLTO‐4drives.SpectraLogicdoesnotsupportdaisy‐
chainingmultipleLTO‐4SCSIdrives.
 Daisy‐chainingLTO‐3drives.
 AmaximumoftwoLTO‐3SCSIdrivescanbedaisy‐chainedonasingle
SCSIbus.
 Whendaisy‐chainingLTO‐3drives,useacablelengththatdoesnotrequire
makingtightbendsinthecable;theminimumlengthis12
inches.
 Keepinmindthateachdaisy‐chaineddriveincreasesthetotallengthofthe
SCSIbus.
 ConnectingmultipledevicesonasingleSCSIbuscanimpactthe
performanceofalldevicesonthebus.Thedatatransmissionratetoany
driveonthebusislimitedtothemaximumtransferrateoftheSCSIbus.
 SpectraLogicdoesnotrecommend,anddoesnotsupport,daisy‐chaining
otherSCSIdevicesonthesameSCSIbusasthedrivesinthelibrary.
Note:Althoughamaximumof15devicescanbeconnectedtoasinglewide
LVDSCSIbus,attachingmorethantwodevicestoasingleSCSIbuscan
haveanegativeimpactontheperformanceofalldevicesonthebus.
 MakesuretheSCSIbusisproperlyterminated.
 IfyouareconnectingeachdrivetoaseparatehostSCSIHBA,youmust
installaterminatoron oneoftheSCSIconnectorsoneachdrive.
 Ifyouaredaisy‐chainingtwoLTO‐3drives,installtheterminatoronthe
unusedSCSIconnector.
Important: Both ends of the SCSI bus must be terminated. If you are daisy-
chaining two LTO-3 drives, make sure that a terminator is installed on the
unused SCSI connector on one of the drives.