What do you have to install at the beginning & the endof the SCSI chain?

both ends of a scsi bus (chain) must *always* be terminated. one end of the bus, usually the scsi host bus adapter, will provide termination for that side. the other end (the device end) typically requires a scsi terminator to be physically attached. however, these days, some devices will offer auto-termination built-in. to find out whether or not your device(s) offer that, you'll have to read the user's manual(s) or contact the manufacturer(s). if you determine that a terminator is what you need, *do not* just put any terminator on the bus just because it looks like it fits. a lot of terminators look the same but, the internal electronics can differ greatly. using the wrong terminator, at the least, will just make the bus more unstable. at the worst, it can cause serious permanent, physical damage to any of the devices on the bus. at one of my former companies, i actually saw a raid box start smoking because one of the production people did just that. a *very* expensive mistake.

at the end you need a terminator so that it knows that is the end of the chain.