At 07:58 PM 9/9/98 -0700, Brad Loomis wrote:
>I am installing an OEM IBM DDRS34560W drive. Since it did not come with any
>manuals, I am not sure of some of the jumper settings.  plan to set it as
>my boot drive with my existing WD 2GB as secondary drive. It will be ID #0,
>which i believe is correct for booting. The ones I don't know are:

>1. Enable Auto Spin-up

"This jumper controls how the drive starts when power is applied. If the jumper
is NOT installed then the drive will spin up automatically after power-on reset.
If the jumper IS installed the drive will NOT spin up unless the host system
issues a 'START UNIT' command to the drive."

If it is your boot drive, you probably don't want this jumper installed.
On the other hand, most controllers are capable of giving a start unit command
if you tell them to. But why bother.

>2. Disable Unit Attention

"When this jumper is installed the drive will not generate a Unit Attention
following a Power On Reset (POR) or SCSI Bus Reset. Any pending Unit Attention
conditions will also be cleared at POR or SCSI Bus Reset."

This would be useful if the drive needs a command from the controller to
spin up. POR means you hit the reset button, or the system spontaneously
rebooted, or you performed a warm reboot. (The SCSI bus sometimes resets
after errors, or when switching from real mode to protected mode drivers,
or (for example) if you refresh Device Manager in Win95 or 98.)


>3. Enable TI-SCTR/WDTR

"When the jumper is installed the drive will initiate synchronous data transfer
speed negotiation (50,68 & 80 pin) and initiate wide data transfer request
(68 & 80 pin) following a SCSI bus reset or power on event."

You want this installed unless you have problems and want to troubleshoot
using these less efficient protocolls.

>4. Enable Auto start delay
>5. Delay Start 6/12

"The auto start delay and delay start pins control when and how the drive can
spin up, with the combination of auto spin up option (JP5).

"When in auto spin up and start delay mode the drive start will be delayed by
a period of time multiplied by its own SCSI address. If auto spin up is
disabled, these jumpers will be ignored."

Since the drive will be ID=0, this setting is not important to you.
This is mainly for the case where there are multiple drives installed
and you don't want to stress the power supply by spinning them all up
at the same time.


>6. Disable SCSI Parity Check

"When this jumper is installed, the drive's SCSI parity checking is disabled."

You definitely want parity checking. Some older devices do not support parity
checking, and you must disable parity on all devices to be able to use them.
You would be advised to get rid of such an old device. And some devices do not
utilize parity checking but will still work with it enabled on the SCSI bus.


DDRS-34560 family references:

http://www.storage.ibm.com/techsup/hddtech/ddrs/ddrstek.htm
performance characteristics of the DDRS models

http://www.storage.ibm.com/techsup/hddtech/ddrs/ddrsjum.htm
Diagrams for the jumper and option block settings.

http://www.storage.ibm.com/techsup/hddtech/ddrs/ultr9es.pdf
Installation Guide

Regards,
Bill

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