Subject: Success with 2 SCSI/single chain on alpha
To: None <>
From: Jon Lindgren <>
List: port-alpha
Date: 04/25/1999 22:52:37
Hey there...  a while ago I posted a note about using two SCSI adapters on
a single bus.  Tonight, I've tried it and it appears to work.

I have an ahc (2940W) and the internal ncr SCSI adapters connected to a
single chain, using the 2940 as SCSI ID 7 and the ncr as SCSI ID 6.  The
drive is an IBM 9ES 4.5G at scsi id 0, with a tape drive at ID 4.

I found that having both adapters enabled in the kernel would cause
"overlapping command" errors.  Disabling the ncr solved that (the kernel
only knows about the ahc).  Also, I had to hardwire the boot device in the
config file, otherwise the kernel complained that "device 0 6 0 0" was
unknown or such.

Uptime of about an hour now, and a tape backup is working fine so far.
The only glitch was the "overlapping" commands.

So now I boot the disk via the ncr, then mount via the ahc.  Now I get my
20mb/s on the drive, while using a [hopefully] more stable driver.

Thanks for all those who sent tips/comments back.  And way to go, NetBSD!