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tecknophreak
01-03-2002, 04:59 PM
if i have my scsi devices on before my comp, it's fine and i can do whatever i want to it.
if the comp is on first, i can't touch it. a cat /proc/scsi/scsi says no attached devices.
and a mt -t /dev/st0 status lets me know no one's home
i've got the adaptec 2940u2w with a generic tape drive hanging on the other end. using rh7.1
[ 04 January 2002: Message edited by: tecknophreak ]
I haven't used a SCSI accelerator with Linux on a PC, but in my experience using them (your model of Adaptec card included) with Windows and Macs, they don't automatically detect devices which come online after bootup. When you boot, the BIOS on the SCSI card initializes and scans for devices, but if you power on a device afterward (the equivalent of hot-plugging), you have to force the card to rescan. On Macs, you use a SCSI probing/mounting applet; in Win9x, the only way I've gotten cards to rescan is to go to Device Manager and hit the "Refresh" button (which doesn't always work). There might be such a method in Linux, but I don't know what it is.
Also, if when you say "a generic tape drive" you mean a 50-pin single-ended SCSI device, you'll have to make sure that it is properly cabled and terminated, as the 2940U2W uses a 68-pin differential LVD bus. Simply connecting the tape drive with a generic 68->50 pin adaptor isn't good enough to insure proper, reliable performance. Make sure you are using the adaptor supplied by Adaptec, or a similar product which properly terminates the high bits, and that the tape drive itself is terminated with a standard 50-pin terminator.
tecknophreak
01-04-2002, 09:33 AM
hot plug huh, i'll check it out? it's a shame i didn't get the card straight from adaptec, or they might have to give me some support.
sorry about the confusion on the tape drive. it's scsi 2 68 pin.
Well, true hot-plugging really refers to removable hard drives (as opposed to Zips, Jaz, etc.), but they use special enclosures with isolation circuitry such that the SCSI bus isn't disrupted/spiked when they are inserted or removed. You can get more on that from Kingston's StoreCase division (http://www.storcase.com/). That by itself still won't solve the problem of actually scanning for the device once it's been inserted, though. It just ensures that you can add or remove drives while the computer is on without glitching the bus.