Dual scsi adaptors and setup

Dual scsi adaptors and setup

Post by Marc MERL » Sat, 04 Jul 1998 04:00:00

>Dear all

>I wonder if you can help.

>Iam trying to install Redhat Linux 5.1.  The problem I have is that in the
>machine there are two scsi adaptors:

>i)Adaptec AHA1542 CP PnP ISA
>ii) Adaptec AHA2940 W/UW

>The problem I have is that I can get Linux to detect one or the other but not

You may have to force the detection of one or the two boards.
Try giving options to lilo (the following two are excerpts from the source

 * LILO params:  aha1542=<PORTBASE>[,<BUSON>,<BUSOFF>[,<DMASPEED>]]
 * Where:  <PORTBASE> is any of the valid AHA addresses:
 *                      0x130, 0x134, 0x230, 0x234, 0x330, 0x334
 *         <BUSON>  is the time (in microsecs) that AHA spends on the AT-bus
 *                  when transferring data.  1542A power-on default is 11us,
 *                  valid values are in range: 2..15 (decimal)
 *         <BUSOFF> is the time that AHA spends OFF THE BUS after while
 *                  it is transferring data (not to monopolize the bus).
 *                  Power-on default is 4us, valid range: 1..64 microseconds.
 *         <DMASPEED> Default is jumper selected (1542A: on the J1),
 *                  but experimenter can alter it with this.
 *                  Valid values: 5, 6, 7, 8, 10 (MB/s)
 *                  Factory default is 5 MB/s.

 *  A Boot time option was also added for not resetting the scsi bus.
 *    Form:  aic7xxx=extended
 *           aic7xxx=no_reset
 *           aic7xxx=ultra
 *           aic7xxx=irq_trigger:[0,1]  # 0 edge, 1 level
 *           aic7xxx=verbose  

I bet just giving aha1542=0x330 (or whatever port you use) should solve the

Quote:>Adaptor i) has the cd rom attached and adaptor ii) has the hard drive

As someone else said, with a simple setup like that, you may be better off
putting everything on one chain (I do have two SCSI chains a home, but
that's because I have more than 10 devices, from slow narrow SCSI 5 to ultra
fast wide SCSI 40 :-D).

Home page: http://magic.metawire.com/~merlin/ (browser friendly)


1. Connecting PCI Dual Channel Ultra3 SCSI Adapter to non IBM RAID - Performance Problem!


I'm connecting a Infortrend SCSI Raid (supporting LVD, Ultra SCSI3, etc
and performing well under Linux) to a F50 with an Dual Channel Ultra3
SCSI Adapter (which should archive up to 160 MB/sec).

Reading 100MB of the same 64k block from the raid (it has 256 MB of
cache) showes me the SCSI Performance of the bus.

It takes about 4 seconds reading from /dev/rhdiskX, which is 25MB/sec.

Looking at the raid it tells me, that AIX is talking async narrow to the

Does anybody have experiance connecting a non IBM RAID on Ultra SCSI3 to
an AIX machine?

I would expect transfer rates at least of 60 MB reading from cache.

Perhaps there is a need for ODM config changes to tell AIX that osdisk
is a LVD disk?

Thanks in advance,


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