SK I posted this in a [l=http://forums.anandtech.com/messageview.cfm?catid=45&threadid=1265404&STARTPAGE=1&zb=902688]FS/FT thread]. I had a hard time finding basic SCSI info when I was looking. HTH
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SCSI can seem very confusing initially. Here are some basics that would apply to getting a drive going.
SCSI is backwards compatible. You can run a U320 drive on a U160 cable on a U2 card.
Every SCSI device in the chain has an ID. Your HBA(SCSI card) is typically 7. Most newer HW will take care of the ID business for you.
Each SCSI chain must be terminated on both ends. The HBA will terminate the end it is on and your cable will have a terminator on the other end. Not all terminators are made equal. There is junk out there and it can/will cause problems.
SCSI connections are commonly in 3 varieties. 50 pin is used by older equiptment and is sometines used on external stuff. 68 pin is the most common. VHDCI is a type of external 68 pin connector. 80 pin or SCA is used in SCSI back planes where drives can be hot swapped. 80 pin carries power. You can get adapters to use an 80 pin drive with your 68 pin cable. It will be a circuit board that will take your 68 pin and power connector and get it all into your 80 pin drive.
LVD is Low Voltage Differential. Is is the signalling scheme used by Ultra2, U160 & U320.
When you buy a SCSI cable it will specifiy how many devices. This number is counting all plugs on the cable. That includes your HBA.
Do not plug unplug SCSI stuff that is not setup fo hot-swap when power is own. SCSI carries power. LVD, low voltage differential, get it?
HSW has a good article:
http://computer.howstuffworks.com/scsi.htm
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