2-8AAA-130SA Series Installation and Hardware GuideAdditional Hints for Connecting SCSI PeripheralsAll SCSI Peripheralsn If you are booting your server from a single SCSI hard diskdrive or bootable array, the boot order (or virtual device order) ofthe disk or array must be set to 0. (See Making the Array Bootableon page 3-5.)n Enable termination power on all SCSI peripherals in the serverso that if you remove a drive that is supplying terminationpower other peripherals will still provide it.n Symptoms of SCSI cabling-related problems are drives notbeing recognized, drives locking up, or drives that deactivate.n Use good-quality SCSI cabling, and minimize the stub lengths.Good-quality cables should not be limp when you pick themup. (See Appendix E, Obtaining SCSI Cables and Converters foradditional information.)Cable Lengthsn The total length of cabling (internal and external) on each SCSIchannel should not exceed the following:– Three m (9.8 ft) if you are using Fast SCSI data transferrates (10 MBytes/sec).– Three m (9.8 ft) if you are using Ultra SCSI data transferrates (20 MBytes/sec for 8-bit peripherals, and 40 MBytes/sec for 16-bit peripherals) and have four or less peripherals(including the Array controller).– One and one-half m (4.9 ft) if you are using Ultra SCSI datatransfer rates and have between four and eight peripherals(including the Array controller).Note: Ultra SCSI data transfer rates do not currentlysupport more than eight peripherals per channel.– Six m (19.7 ft) if you are using 5-MByte/sec asynchronous orsynchronous data transfer rates.n When calculating the total length of the bus, be sure to includethe cabling inside any array enclosure.
