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From: dupuy@cs.columbia.edu (Alexander Dupuy)
Newsgroups: comp.sys.sun
Subject: Sun usable disk SCSI ID's
Keywords: Hardware
Message-ID: <8905171902.AA13727@cs.columbia.edu>
Date: 17 May 89 19:02:03 GMT
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Organization: Sun-Spots
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> c) There are 8 SCSI addresses, and 8 Logical Unit Numbers available in the
> Sun SCSI implementation - the Sun Host Adaptor take address 7, so there
> are 7 free.  Asumming you have a tape at address 4, this makes more like
> 48 possible disks on a SCSI bus. 6 if you are using Embedded SCSI (direct)
> controllers with no LUN's.

I find this interesting, and yet puzzling, since we have run Exabyte tapes
with the thumbwheel SCSI ID (=?= SCSI address) set to 7, and it seems to
work fine.  If in fact the Host Adaptor uses address 7, this would seem
not to prevent tapes or disks from using this address as well (perhaps
because they are not SCSI masters?).  Here are the relevant lines from our
GENERIC Sun-3 config:

controller      sc0 at vme24d16 ? csr 0x200000 priority 2 vector scintr 0x40
disk            sd0 at sc0 drive 0 flags 0
disk            sd1 at sc0 drive 1 flags 0
disk            sd2 at sc0 drive 8 flags 0
#disk           sd3 at sc0 drive 9 flags 0
tape            st0 at sc0 drive 32 flags 1
tape            st1 at sc0 drive 40 flags 1
#disk           sf0 at sc0 drive 8 flags 2
tape            smt0 at sc0 drive 48 flags 4
tape            smt1 at sc0 drive 56 flags 4
controller      si0 at vme24d16 ? csr 0x200000 priority 2 vector siintr 0x40
controller      si0 at obio ? csr 0x140000 priority 2
disk            sd0 at si0 drive 0 flags 0
disk            sd1 at si0 drive 1 flags 0
disk            sd2 at si0 drive 8 flags 0
disk            sd3 at si0 drive 9 flags 0
tape            st0 at si0 drive 32 flags 1
tape            st1 at si0 drive 40 flags 1
#disk           sf0 at si0 drive 8 flags 2
tape            smt0 at si0 drive 48 flags 4
tape            smt1 at si0 drive 56 flags 4
controller      se0 at vme24d16 ? csr 0x300000 priority 2 vector se_intr 0x40
disk            sd0 at se0 drive 0 flags 0
disk            sd1 at se0 drive 1 flags 0
disk            sd2 at se0 drive 8 flags 0
disk            sd3 at se0 drive 9 flags 0
tape            st0 at se0 drive 32 flags 1
tape            st1 at se0 drive 40 flags 1
tape            smt0 at se0 drive 48 flags 4
tape            smt1 at se0 drive 56 flags 4

The smt driver is from Delta Microsystems.

@alex
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