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Date:      Fri, 07 Nov 1997 23:20:43 -0600
From:      dkelly@HiWAAY.net
To:        joerg_wunsch@uriah.heep.sax.de (Joerg Wunsch)
Cc:        chat@FreeBSD.ORG
Subject:   Re: hardware 
Message-ID:  <199711080520.XAA16195@nospam.hiwaay.net>
In-Reply-To: Message from j@uriah.heep.sax.de (J Wunsch)  of "Sat, 08 Nov 1997 00:16:15 %2B0100." <19971108001615.TR41338@uriah.heep.sax.de> 

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J Wunsch writes:
> 
> I don't think it's much lower-ended than SCSI.  The drive electronics'
> complexity is probably the same.

Am not sure if similar SCSI/IDE models from the same manufacturer 
actually use the same CPU's. While memory is cheap, its very common for 
an IDE drive to have only 128k, while thats a very low end SCSI drive. 
I don't shop for IDE drives, so I don't know if any have more than 
128k. 512k or 1M isn't unusual for SCSI. Using that as an example 
would it be surprise if there wasn't a similar difference in CPU 
performance?

> I've got too many surprises with too many different IDE drives to ever
> touch it again.  I'm used to hot-plug SCSI devices all over the place
> (first plug them onto the bus, then set the power plug), and i enjoy
> the feature to only set a single jumper on the new device before i
> plug it in.

The fine print in many SCSI manuals lists this as a feature, not a 
risk. I'm offline now but somewhere near 
http://www.storage.ibm.com/techsup/hddtech/hddtech.htm, my DCHS-39100 
is specifically documented for hotswap, as long as you don't have the 
SCA version where power and everything is on the same connector.

> /sbin/dmesg usually tells me what ID is still available.

Care to remind me how to get FreeBSD to recognize a SCSI device that 
wasn't there when the kernel initialized? 

"man 8 scsi":
 ...opening a fixed SCSI device has the side effect of reprobing it,
    and probing with the bus with the -p option should bring on line
    any newly found devices.

Any examples handy? Seems to suggest it requires locked down (fixed?) 
SCSI devices. But I'm not sure how to go about hot swapping. Could it
be so simple as to attempt a mount? Or to open it with sysinstall for 
partitioning and prep?

--
David Kelly N4HHE, dkelly@hiwaay.net
=====================================================================
The human mind ordinarily operates at only ten percent of its
capacity -- the rest is overhead for the operating system.





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