Adaptec 131CA Installation And Hardware Manual

Contents

2-11Installing the AAA-131CA Adapter and Connecting SCSI DevicesConnecting External SCSI Array Enclosures (StorageSubsystems)If you are installing the AAA-131CA adapter in a powerful, high-end desktop system, you may decide to use a SCSI array enclosurefor your SCSI disk drives, instead of installing the drives in the com-puter itself. Array enclosures offer a number of advantages:n New disks can easily be added.n Bad disks can easily be identified and replaced.n If the enclosure supports hot swapping1 , you can add or removedisks without pausing data I/O on the SCSI bus or shuttingdown the system.Figure 2-9 shows a typical setup between the array enclosure andthe computer. To install your SCSI devices in an array enclosure,refer to the enclosure’s documentation. The following information isprovided to help you properly connect your enclosure to the com-puter. (See Appendix E, Listing of Vendors for a list of popular arraystorage enclosure and disk drive manufacturers.)n All rules for SCSI ID and termination must be followed wheninstalling SCSI devices in an array enclosure.n Ideally, the array enclosure itself should provide terminationcapability, either on the SCSI backplane or with an attachableactive terminator, as shown in Figure 2-9, and you should dis-able termination on all the drives in the enclosure. If you termi-nate the SCSI bus by enabling termination on a drive, you mayrun into problems if you have to replace that drive and youthen forget to terminate the replacement drive.1 Hot swapping support means that the array enclosure electrically isolates thebad disk’s SCSI connector from the SCSI bus while the disk is beingswapped to prevent data corruption. Data can still be transferred to andfrom the remaining good disks while the bad disk is replaced. Check withthe manufacturer of the array enclosure if you are not sure whether it sup-ports hot swapping