Advanced Host Adapter Settings - Dell PowerEdge 4200 Series User Manual

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Enable Disconnection — This option (sometimes
called disconnect/reconnect) determines whether the
host adapter allows the SCSI device to disconnect
from the SCSI bus. Enabling disconnection allows
the host adapter to perform other operations on the
SCSI bus while the SCSI device is temporarily dis-
connected. The default setting is Yes.
Leave Enable Disconnection set to Yes if two or
more SCSI devices are connected to the host adapter.
This optimizes SCSI bus performance. If only one
SCSI device is connected to the host adapter, set
Enable Disconnection to No to achieve slightly bet-
ter performance.
•
Initiate Wide Negotiation — This option determines
whether the host adapter attempts 16-bit data transfer
instead of 8-bit data transfer. The default setting is
Yes.
NOTE: Some 8-bit SCSI devices may have trouble
handling wide negotiation, which may result in
erratic behavior or a hang condition. For these
devices, set Initiate Wide Negotiation to No.
When this option is set to Yes, the host adapter
attempts 16-bit transfer. When this option is set to
No, 8-bit data transfer is used unless the SCSI device
itself requests wide negotiation. The effective trans-
fer rate is doubled when 16-bit data transfer is used
because the data path for wide SCSI is twice the size
of normal 8-bit SCSI.
•
Send Start Unit Command — This option determines
whether the start unit command is sent to the SCSI
device during the boot routine. The default setting is
Yes.
Setting this option to Yes reduces the load on your
computer's power supply by allowing the host
adapter to start SCSI devices one at a time when you
boot your computer. When this option is set to No,
the devices are allowed to start at the same time.
Most devices require you to set a jumper before they
can respond to this command.
NOTE: For many devices, if Send Start Unit Com-
mand is set to Yes, the boot routine time will vary
depending on how long it takes each drive to start.
3-4 Dell PowerEdge 4200 Systems User's Guide

Advanced Host Adapter Settings

The advanced host adapter settings should not be
changed unless absolutely necessary. These values are set
by Dell, and changing them may cause conflicts with the
SCSI devices.
•
Host Adapter BIOS — This option enables or dis-
ables the host adapter BIOS. The default setting is
Enabled.
NOTE: Several SCSISelect options are not valid
unless the host adapter BIOS is enabled.
If you are booting from a SCSI hard-disk drive con-
nected to the host adapter, the BIOS must be enabled.
You should disable the host adapter BIOS if the
peripherals on the SCSI bus (for example, CD-ROM
drives) are all controlled by device drivers and do not
need the BIOS.
•
Support Removable Disks Under BIOS As Fixed
Disks — This option controls which removable-
media drives are supported by the host adapter
BIOS. The default setting is Boot Only. The follow-
ing choices are available.
CAUTION: If a removable-media SCSI device is
controlled by the host adapter BIOS, do not
remove the media while the drive is on or you may
lose data. If you want to be able to remove media
while the drive is on, install your removable-
media device driver and set this option to
Disabled.
— Boot Only. Only the removable-media drive
designated as the boot device is treated as a
hard-disk drive.
— All Disks. All removable-media drives supported
by the BIOS are treated as hard-disk drives.
— Disabled. No removable-media drives are
treated as hard-disk drives. In this situation,
software drivers are needed because the drives
are not controlled by the BIOS.