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How do you handle setting up 80 pin scsi drives?

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September 13, 2010 3:34:53 PM

I have a bunch of 80 pin scsi drives and no enclosure. Thinking I would a use a length of 80 (or parallel 2 40's) conductor ribbon, break out 68 conductors for idc 80 pin connectors (assuming they're out there) and daisy chain the power pins to a molex power plug. Any thoughts or suggestions short of dropping $$$$ on an enclosure? Could etch my own copper I suppose....
September 14, 2010 3:00:04 PM

Are you sure they are 80-pin SCSI drives? Are they all the same model #?
How many drives are you talking about? And which SCSI controller do you have?
Some controllers can handle up to 15 drives and there are SCSI cables to match.
Would your main power supply handle that many drives? An external enclosure
with its own power supply shouldn't cost much and would be a good idea if there
are more drives than you have bays for in your main box.
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September 14, 2010 4:32:11 PM

Yes, they are ST318404LC. Notice the LC, indicating an 80 pin connector (Power is supplied via this connector. The controller is an AHA-2940UW, uses a 68 pin external, 50 and 68 pin internals. Single channel version of the 2940, SCSI-2 support. I haven't found an 80 pin cable that breaks out the power for each drive. EBaying returns >$200 for enclosures that have merit.

So, I take it that you haven't seen this done? Neither have I, that's why I'm asking.
You do have good points, however.
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September 15, 2010 1:59:55 PM

Sorry but I've never seen one. The only cable that I had heard of that included power was for a laptop ide drive.
Don't know how you'll connect to the 2940UW.

I was thinking even getting a full tower case and using that for the drives if you have more drives than will fit
easily in your current case.

The Seagate document at http://www.seagate.com/support/disc/manuals/scsi/757895... mentions only
a single drive per connection but I may be reading that wrong.

Do you know what controller they were originally connected to and in what type of computer? Any chance you
could get a controller & cable from their old computer?

Frankly it may be far easier and cheaper to go with a new SATA or IDE drive. They're generally around
$50 for 500gig. I had been using SCSI 18g drives for around 20 years but finally had to switch when
the Adaptec controller and drives started going bad. Not to mention the drives were only 18g and cost around
$300-$400 when I bought them new back in the late 80s.

Sorry I couldn't be of more help.
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September 15, 2010 3:17:46 PM

Paul, the 80 pin connectors are intended to be used as hot pluggable chassis drives. Typically, there is a backplane that these plug into. The backplane handles the power, id, and termination. A 68 pin cable and a power source will plug into the backplane and be distributed to the drives via the 80 pin. I have are some cast-off drives from a scheduled maintenance update. What I am currently looking at is snagging a couple of backplanes from ebay and seeing if I can't that to work. I found a couple of 10 bay planes for $10. I think that if I hook up a couple of dreg power supplies I should be on the air. This should be even less expensive and a whole lot sturdier than a length of ribbon cable, and a slew of idc connectors.

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September 16, 2010 12:04:26 PM

Ok, that sounds like it would work. but you're still going to need a BIG cabiniet to put them in if you're talking
between 10 & 20 drives. a full tower at least. or maybe 2 as I'm not sure you could put 2 backplanes in a
single cabinet ( but I have no experience with them ). plus fans to keep it cool. not to mention that you'll need
another SCSI card as the 2940UW only handles 15 drives max. what OS are you running?

But look at it another way. if it works then you've got at most 360g on 20 drives. do they still make them anymore?
what happens when they start crashing? for under $100 you can get 500g to 1000g on a single drive and have
no problem putting it in a modern computer ( and not much problem putting it in an older computer ).

But if it is just to prove that "Yes I can!" then I say Go For It! and post a picture when you get it running.

Good Luck.
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October 17, 2010 2:51:01 PM

Hello sdad,
Did you find a way to connect your scsi drives yet?
I have a couple of drives and I bought the 68 to 80 pin adapters but the host adapter doesn't recognize them.
I bought an HP Netserver LH4 backplane but it has a 14-pin power connector which pinout I don't know.
Did you buy backplanes yourself and did you manage to make them working?

Thanks
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October 17, 2010 4:27:52 PM

Yes I do have them working. I bought a couple of Compaq UW2 backplanes that also has a "Molex" dual row connector for power. Sitting along side mine is also a standard 4 pin Molex for a single drive, so getting pinouts for my 12 pin (as compared to your 14) was easy. Power is 12, 5 and gnd. The large connector is to handle the high current demands from all those drives. My backplane handles 10 drives each. First thing I did was use an ohm meter to group the pins into 3 groups. I then used the ohmmeter to map each group to the smaller single drive connector. If you don't have that smaller connector then it will take a little research on your part, but shouldn't be too bad with Google's help. Locate a known 12, 5 and ground pin on one of the 80 pin drive connector (or from a known device on the board, like a ground plane, or an ic pin.). The pinouts should be easy to come up with, I believe they are toward the outer side of the connector. You say you have an adapter? Trace that out. Should be the same.

Couple of questions regarding the adapter you bought. Are you supplying power via the molex connector?, are you assigning an address not in conflict with host? are you terminating the drive? can you hear the drive spool up? Jumpers on the adapter should deal with drive options. Keep in mind that the backplane most likely does address asigns and termination. Watch the hba's address however, don't test the board with a drive in a conflicting slot, won't work. What you might want to do is move the controller's address above the slot assignments of your board, now its a non-issue.
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October 24, 2010 12:48:08 AM

Paul, I was re-reading these comments because of a follow-up from the forum. Understand that these arrays typically do not reside in a typical home box, rather they are found in either a separate chassis, usually a row of up to 14 drives stacked next to each other, or in a server chassis which could be 20" wide, 10" high, 30" deep and weigh in at 100 lbs. Google a Compaq DL580G2. Huge. Absolutely right about fans (note the plural)
I do have the backplanes working, just sitting on the bench right now. Each takes a good sized power supply to handle 10 drives. And yes, I have two controller boards.

There are some very good reasons for using the scsi drives, most reasons revolve around reliability (redundancy) accessibility, expandability.

If you think that 15 drives in a scsi array is large, consider using a fiber channel loop. 120+ drives in a single loop! Imagine if you will what that does to the old light bill.
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