Scsi bus interface definitions, Boot device options, Scsi device configuration settings – Dell PowerEdge 6650 User Manual

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SCSI Bus Interface Definitions

The basic host adapter settings are the SCSISelect settings most likely to require modification:

Host Adapter SCSI ID — Sets the host adapter's SCSI ID. The default setting is SCSI ID 7, which allows the host adapter to support narrow SCSI
devices in addition to wide SCSI devices. Dell recommends that you leave the host adapter set to SCSI ID 7.

SCSI Parity Checking — Determines whether the host adapter verifies the accuracy of data transfer on the SCSI bus. The default setting is Enabled.
You should disable SCSI Parity Checking if any SCSI device connected to the host adapter does not support SCSI parity; otherwise, leave it enabled.
Most SCSI devices support SCSI parity. If you are unsure whether a device supports SCSI parity, consult the documentation for the device.

Host Adapter SCSI Termination — Sets termination on the host adapter. The default setting for the AIC-7892 host adapter is Enabled or Automatic.
Dell recommends that you leave this option set to the default.

Boot Device Options

The boot device options allow you to specify the device from which to boot your system:

Boot SCSI ID — Specifies the SCSI ID of the boot device.

Boot LUN Number — Allows you to specify a particular logical unit number (LUN) from which to boot your boot device if your boot device has multiple
LUNs and BIOS Multiple LUN Support is enabled (see "

SCSI Device Configuration Settings

"). The default setting is LUN 0.

SCSI Device Configuration Settings

The SCSI device configuration settings allow you to configure certain parameters for each device on the SCSI bus. To configure a specific device, you must
know the SCSI ID assigned to that device. If you are not sure of the SCSI ID, see "

Using the SCSI Disk Utilities

Sync Transfer Rate MB/sec — Sets the maximum synchronous data transfer rate that the host adapter supports.

The AIC-7892 host adapter supports rates up to 160 MB/sec. The default for the AIC-7892 host adapter is 160 MB/sec.

If the host adapter is set to not negotiate for synchronous data transfer, the maximum synchronous transfer rate is the maximum rate that the host
adapter accepts from the device during negotiation. (This setting is standard SCSI protocol.)

Initiate Wide Negotiation — Determines whether the host adapter attempts 16-bit data transfer instead of 8-bit data transfer. The default is Yes.

When this option is set to Yes, the host adapter attempts 16-bit data transfer. When this option is set to No, 8-bit data transfer is used unless the SCSI
device itself requests wide negotiation. The effective transfer 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.

Enable Disconnection (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
disconnected. 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 better performance.

Send Start Unit Command — Determines whether the start unit command is sent to the SCSI device during the boot routine. The default is Yes.

Setting this option to Yes reduces the load on your system's power supplies by allowing the host adapter to start SCSI devices one at a time when you
boot your system. 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.

Boot LUN Number

SCSI Device Configuration:

Sync Transfer Rate MB/Sec

160

Initiate Wide Negotiation

Yes (Enabled)

Enable Disconnection

Yes (Enabled)

Send Start Unit Command

Yes (Enabled)

Enable Write Back Cache

Yes, No, or N/C