[3879] in linux-scsi channel archive
Re: changing host ID of ncr53c810?
daemon@ATHENA.MIT.EDU (Harald Milz)
Sat May 9 12:51:03 1998
Date: Sat, 9 May 98 14:09 CEST
From: hm@seneca.muc.de (Harald Milz)
To: linux-scsi@vger.rutgers.edu
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Reply-To: h.milz@seneca.muc.de
Richard Waltham (dormouse@farsrobt.demon.co.uk) wrote:
> #ifndef SCSI_NCR_MYADDR
> -#define SCSI_NCR_MYADDR (7)
> +#define SCSI_NCR_MYADDR (6)
> #endif
In order to allow for setting the ID without patching the driver, I strongly
suggest a kernel/module command line parameter to set the host adapter SCSI
ID. This will be important as soon as some shared SCSI bus high
availability software package starts to do real work. Since the SCSI ID
will not change very frequently, it should suffice to set it via the
adapter BIOS setup routines. But apparently not all adapters allow this
> Apart from the host ID there are other problems that could occur but thats
> another story. But you should be ok if you only access the drives from one
> system at a time.
No, there's a catch. The SCSI bus needs to be terminated at the far ends
ONLY. If you put the SCSI peripherals "between" the adapters, you need to
disable bus termination on the adapters and use a Y cable
(http://sunsite.unc.edu/pub/Linux/ALPHA/linux-ha/High-Availability-HOWTO-7.html)
to make sure the bus isn't unterminated at one end if the machine at this
end is switched off. You can also put the SCSI host adapters in the
"middle", disable termination on the adapters and attach terminators at the
far ends of the SCSI bus. Any way the SCSI host adapters need to have
termination disabled. More is documented in the HA HOWTO pointed to above.
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