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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: MrZammler on March 07, 2005, 11:59:07 AM
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Hi,
I have an external cdrw scsi drive connected to the A3000. How safe is it turn it on/off while the amiga is powered on?
I hate reboots!
thanks
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I don't know whether this is different from the A3000, but on my A4000T I regularly switched off an external device while the Amiga was still running (obviously not during access to the device). I also have a Yamaha CDRW and it was in an external box for more than 2 years. Then I had an external SCSI HD that was formatted for MAC (Shapeshifter or Fusion, can't remember which) and lately formatted for FAT95 sharing between Amiga and PC. I have switched them all off at one time or another and no damage has been done to my Amiga. Same applies to switching them off while connected to the external connector of the CybSCSI device.
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I have an A3000 with external SCSI Magneto-Optical Rewritable Removeable Media drive since circa 1990 and I have turned the external drive off/on with or without the Amiga being on 74 GAZILLION times and never had any problem whatsoever.
Back in the 1990's my A3000 was on 24 hours a day and I just turned off/on the external drive as needed (about 20 times per day).
A3000 SCSI RULEZ 4-EVA :-)
P.S. Do NOT turn the drive off in the middle of a write operation. :-D
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@ChaosLord
LOL, ok, seems safe to me then! thanks!
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MrZammler wrote:
@ChaosLord
LOL, ok, seems safe to me then! thanks!
SCSI is supposed to be resilient like this. :-) However, if you have multiple devices on the chain, you want to watch out for termination issues if nothing else -- if, say, your internal HD is on the same chain, and the external device is both providing termination on the external end and providing TERMPWR for the bus, you can expect to risk flakiness on the chain when it's switched off.
Note that TERMPWR is supposed to be provided by the 'initiator' (http://h000625f788f5.ne.client2.attbi.com/scsi_faq/scsifaq.html#Generic050) (read 'the controller'), so you should be safe, as long as you haven't gone around jumpering your external stuff to ignore it and take it from the drive PSU (or it didn't come like that to begin with).
Meanwhile, for that concern raised in the above -- how long is 'longer?' -- it can be a good idea to jumper that way, let your external box power itself (the "TERMPWR to on drive terminator only" option some peripherals present), and practice power hygeine (read: not turning the terminating unit's PSU off if you have other peripherals you need to keep using on the same chain). You only reallly have to worry about this if you're having termination-related bus problems, or are paranoid about avoiding them.
(Call me stupid, but active terminators *do* still draw or have-the-option-to-draw from TERMPWR, right? How else could they make them standalone?)
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@MrZammler
If you're REALLY paranoid about it, you could use the following tool (on Aminet):
"disk/misc/Sleeper20.lha Stops SCSI-HDs during inactivity"
Edit the tooltypes, power down the motor to the drive(s) on the external leg of the SCSI chain using the GUI, THEN turn off power.