Subject: Re: Another changer, another changer problem
To: None <>
From: Greg A. Woods <>
List: current-users
Date: 10/01/1998 18:24:26
[ someone who's attribution has been lost in the mists of time said: ]
> Uh, actually, when I said SCSI controller, I didn't mean the SCSI bus
> (esp0), I meant the controller as in the card that drives the disk
> drive. Currently, most, if not all, manufacturers ship disks that have a
> one-to-one disk-to-controller mapping; I'd like it if there were some
> that at least could split 2 disks (LUNs) for one controller (Target).

There are, but they generally do a whole lot more than you might be
expecting.  For example some SCSI attatched RAID controllers can offer
logical volume to LUN mapping.  In fact some of these controllers are
SCSI-EIDE and offer a very cost effective way of getting decent
performance out of cheap and fast but otherwise useless drives.

The SCSI standard clearly defines LUNs and they should be properly
supported throughout (i.e. regardless of what the target devices are, so
long as it's legal in the standard to have multiple LUNs for them).

I do have several Emulex MT02 controllers, and at least one
SCSI-to-ST506 controller, and a SCSI-to-ESDI controller.  The former two
are probably not worthy of use, but the latter still is though I'll
probably keep it in my AT&T 3B2 where it has full OS support, including
explict device naming such as "c0t0d0s0" which means "controller 0,
target 0, disk(LUN) 0, slice 0" (something I wish NetBSD had).

							Greg A. Woods

+1 416 218-0098      VE3TCP      <>      <robohack!woods>
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