Fuzzy on SCSI Cabling

[Bill in SD, CA]

If the maximum cable length is 3 meters does that mean:

1. The sum total in the chain/bus?

or

2. Maximum between devices?

Does anything change if the card has both internal and external channels?



Thanks,

Bill

[SeanC]

I believe that's the maximum length between devices.

What is your definition of "channels"? If you mean connectors then you still have the maximum # of devices 15 for the card. If the card has multiple SCSI channels, then you can plug up to 15 devices per channel. Your SCSI card documentation would say whether you have a multi-channel or not.

Sean

[Bill in SD, CA]

Perhaps what I should have said was "connectors" not channels.

Bill

[Tomteriffic]

Bill, the maximum cable length is 3 meters per channel, regardless of whether the devices are internal, external or both.

If you have a true dual-channel card (i.e., you're able to run up to 30 devices), then the wise move is to split the devices into internal and external chains. Some cards, though have only one channel, but have both internal and external connectors for it.

What card do you have in there? With a 3 meter cable length limitation, it sounds like a SCSI 2 type card of some sort, and there weren't that many true dual channel cards out there.

[Bill in SD, CA]

I'm actually studying for my A+ and I was not sure about the maximum length. The 3 meter example was just that, an example.

I'm looking at the different specs:

SCSI-2 (fast) 8 devices (including card) 3 meters
SCSI-2 (fast wide) 16 devices (including card) 3 meters

and it occurred to me that 3 meters wasn't a lot of cable for 16 devices.

Bill

[Tomteriffic]

Originally posted by Bill in SD, CA
and it occurred to me that 3 meters wasn't a lot of cable for 16 devices.

Bill

You're right. I used to fight that all of the time. The newer flavors of SCSI have, IIRC, a 12 meter limit.