[rescue] Question for the SCSI gurus

dsimmons dsimmons at libx.siu.edu
Tue Jan 24 11:06:03 CST 2006

Object of the game: to shove one (or even two) more drives into an E250
which already has a fully-populated 6-drive backplane without having to
hang them from the inside of the chassis with zip-ties.

Note: I freely admit to only a high-level understanding of SCSI. If what
I propose is foolish for some reason, please don't hesitate to tell me

My E250 has dual single-ended ultra/wide SCSI. One chain is the factory
bus which talks to the backplane, on which I presently have 6 ST39102LC
drives with standard SCA80 connectors. This chain also connects (via a
50-pin IDC cable leading off the top of the backplane) to the removable
media bay where I have a single CDROM. I do not have a floppy or a tape
drive, so I have two unused bays, and my tinker-gene has presented the
following question: can I get a SCA80/IDC50 adapter to plug into the
back of one of my Seagate drives and then plug the adapter into the
50-pin IDC, for example, where the tape drive would normally go? I
presume that it would have to have an ID <7 because it would be on a
narrow cable, but it would be identical to the other drives, so I wonder
if I could do this and not suffer an SE fallback speed for the entire
chain. http://store.a2zcable.com/ra41.html and similar items on eBay
seem like they would be exactly what I need except that some (not all)
of the SCA80/IDC50 adapters I find specify "Not for use with LVD
drives". Why not? Are there SCA80/IDC50 adapters which ARE for use with
LVD devices? If I ignore this warning and use one of these adapters with
an LVD drive anyway, what will happen? Will the drive explode? Will I
just get a slow chain? No communication with the drive? Sun engineers
will show up at my door and pound me? What?

Thanks in advance for your time and any suggestions!

Doug Simmons
Procedures and Systems Analyst II
Morris Library Systems
Southern Illinois University Carbondale

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