Help understanding SCSI connections, channels, Buses and Termination
Posted on 2010-09-02
We have a server which has an onboard SCSI controller and an Adaptec 2100S PCI SCSI card installed. From the SCSI card is a cable with 6 connections. The second connection on the cable is connected to a disk RAID Array which contains 5 disks via a SAF-TE hot swap backplain.
Can you confirm that the system sees the onboard SCSI controller completely seperately from the SCSI PCI card? That is they can both have their own sequence of SCSI IDs. Would they be on seperate BUSES and can each BUS have is own sequence.
My understanding is that everydevice (including cards) would have their own SCSI ID. Is the following correct/possible?
Bus A SCSI ID 1 - Onboard SCSI Controller
Bus A SCSI ID 2 - Tape Drive
Bus B (PCI Card) SCSI ID 1 - PCI SCSI Card
Bus B SCSI ID 2 - RAID Hotswap BackPlain
Bus B SCSI ID 3 - SCSI Drive 1 in RAID
Bus B SCSI ID 4 - SCSI Drive 2 in RAID
Bus B SCSI ID 5 - SCSI Drive 3 in RAID
Bus B SCSI ID 6 - SCSI Drive 4 in RAID
Bus B SCSI ID 7 - SCSI Drive 5 in RAID
My final question is about termination. If the first cable connector is connected to the PCI Card (with auto termination) and the Second cable connector connected to the RAID backplain, should the terminator be at the third cable connctor possition or is it ok to have the connector at the very end of the ribbon with entry connectors? At the moment is is at the very end of the cable and clips on so that it can not be easily removed.
Thanks for your help