4.5 Configuring Channels

Using RAIDWatch Manager, you can modify the configuration of any channel on the controller. You can set the channel operation mode to host or drive, enable or disable channel termination, set SCSI IDs, set the transfer clock rate for synchronous communication, and select the transfer width.

Channel configuration settings are available under Physical View in the RAID View window.

The following describes user-configurable channel parameters:

1. Channel Mode. This parameter sets the operation mode of a particular channel on the controller. It configures the operation mode to either host or drive, where a host channel is used when connecting to a host and a drive channel is for connecting to SCSI drives. Any SCSI channel on the controller can serve as either a host or drive channel. Channel 0 is the default host channel with SCSI ID number 0.

2. Termination. This parameter enables or disables SCSI channel termination. SCSI cables must be properly terminated at both ends; that is, when connecting one end of a SCSI cable to a channel, the termination of the channel must be enabled. Note that the other end of the cable must also be properly terminated.

You can terminate the other end of the cable by installing or enabling termination on the SCSI drive farthest from the controller or by installing an external terminator on the end connector. The latter method is recommended so that removal of the drives will not affect cable termination. All other terminators must be removed or disabled making sure that only one terminator is installed on each end. (SentinelRAID series users, check your hardware documentation for additional termination information.)

3. Default Xfer Clock (in MHz), Default Xfer Width. These parameters set the data transfer clock rate for synchronous communication over the SCSI bus, and enable or disable wide transfer, respectively.

Data that is transferred across the SCSI bus in synchronous transfer mode is clocked using a synchronous transfer clock signal. The frequency of this signal determines the rate at which data is transferred. If, for example, the synchronous transfer clock is 10 MHz, data transfer rate will be 10 million bytes per second (assuming narrow transfer).

Data transfer across the SCSI bus can be either 8 bits or 16 bits at a time. The former is referred to as narrow transfer, while the latter is referred to as wide transfer. At the same synchronous transfer clock rate, data transfer using wide transfer will be double that of narrow. With a transfer clock of 10MHz, the data transfer rate will be 10 Mbytes/second under narrow transfer, and 20Mbytes/second using wide.

Occasionally, under conditions in which SCSI signal quality is poor, such as with extremely long cables, poor connections, or bad termination, it may be necessary to reduce the synchronous transfer clock to allow the SCSI channel to function normally. Worst case, it may be necessary to switch to asynchronous communication mode.

Furthermore, certain older SCSI devices may only support narrow transfer and behave abnormally when attempting to negotiate wide transfer. Under such conditions, wide transfer may need to be disabled, forcing the controller to use narrow transfer mode with that device.

4. ID pool / PID / SID. This parameter sets the SCSI ID of the channel. Each channel must have a unique SCSI ID in order to work properly. SCSI ID ranges from 0 up to 15, with 0 assigned as the default value for host channels, and 7 for drive channels.

It is necessary to create a SID on every I/O channels in redundant controller configuration.  The default are 6 for SID and 7 for PID on drive channels.  The default values for Infortrend's dual redundant configuration are 8 for SID and 9 for PID.  For more information, please refer to the hardware documentation that came with your controller.

Setting the configuration of a channel

1. Display Physical View by clicking on the Physical View command button under the RAID View introduction or by selecting Physical View from the RAID View navigation panel.

2. From Physical View, double-click on the corresponding SCSI Channel icon of the target channel. SCSI Channel icons are displayed in the navigation panels on the left side of the RAID View window. The Channel Settings configuration will appear in the RAID View content panel.

3. If you are using a SCSI-to-SCSI controller, select the channel mode from the Channel Mode drop-down list box. To select, click on the down-arrow button at the right of the box, then select the option you want. If you want to configure the selected channel as a host channel, select Host; to configure as a drive channel, select Drive.

4. From the Termination drop-down list box, specify whether to enable the channel termination or not. To enable, select On; to disable, select Off. (SentinelRAID series users, check your hardware documentation for additional termination information.)

5. If you want to assign a different SCSI ID to the selected channel, choose the new ID from the ID pool scroll list box. When selecting an ID, be sure that it does not conflict with the other SCSI devices on the channel. The ID pool lists all of the channels. Highlight the ID you want to use and click Add next to either the PID (Primary ID) or SID (Secondary ID) window.

6. To change the speed of the SCSI bus synchronous transfer clock, choose the new value from the options listed in the Default Xfer Clock drop-down list box.

7. From the Default Xfer Width drop-down list box, select whether to use narrow or wide transfer. To use narrow transfer, select Narrow; to use wide transfer, select Wide.

8. Click OK to save the new channel configuration into the non-volatile memory (NVRAM) of the controller. You will be prompted for a password in order to complete the changes.

4.5.1 Configuring New or Unassigned Drives

New and unassigned drives have some additional configuration options listed by channel under Physical View.

Drive Info (no configurable parameters, readouts only)

Drive Information: Slot Number, Channel Number, ID Number, Capacity, Status, Transfer Rate, Logical Drive ID, Vender/Product ID.

Copy & Replace:

Used to copy and replace a current member drive of a logical drive. Choose the target drive by clicking on its icon in the Copy& Replace window pane.  Click OK to replace the target with the selected new drive.


NOTE:

This operation is intended for use in expanding a logical drive by replacing all member drives one at a time.  Also, as the available size will be limited to the maximum size of the smallest hard drive, it is recommended that all drives in a logical drive be the same size.


Scan New Drive

1. Choose the channel number and ID where the new drive is located.

2. Click OK. The system will ask for a password and then scan for a drive with the specified ID. It will then either display a successful confirmation message or an error message.

3. Repeat these steps to scan additional drives.

Add Spare

Choose a logical drive to which to add a spare. Once it is displayed in the Target LD text box, click the Local button (to make a local spare) or the Global button (to make a global spare).


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