2.5 In-band SCSIWhat is it and what is it used for?
These days more and more external devices require communication with the host computer for device monitoring and administration. This is usually done through RS-232C ports.
An alternative means of communication is now available for SCSI-to-SCSI RAID controllers – in-band SCSI. The traditional way for SCSI controllers to communicate with the host computer has been via software (such as RAIDWatch) using an RS-232C connection. With in-band SCSI, integrators have more flexibility. They may use RS-232C or the existing SCSI cable instead.
In-band SCSI is particularly useful when creating a new RAID. In order for a host to "see" the controller, and thus for Primary and Secondary agents, and RAIDWatch Manager to manage the controller, it must first be configured as a peripheral device. In-band SCSI allows you to do this using Text RAID Manager.
How is it able to use the SCSI cable?
In-band SCSI technology translates the original commands into standard SCSI commands. These SCSI commands are then sent to and received from the SCSI RAID controller. RAIDWatch can manage the RAID controller just as it could before via RS-232C. (Note: it is assumed that users of in-band SCSI possess the following – a third-party SCSI adapter and a channel on their Infortrend RAID controller that can be designated as a host channel. Both of these are required for in-band SCSI communication between the host and the RAID controller.)
Configuring a RAID Controller to Use In-band SCSIRAID Controller Adjustments
Some adjustments must be made to the RAID controller and to the host computer's SNMP settings before the two can communicate using SCSI commands. The RAID controller settings can be changed using the Front Panel. (Your front panel may be different in appearance from the one shown in this example.)
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From the Main Menu, press t or s to select "View and Edit Configuration Parameters."
Press <Enter>; and then use the t or s to select "Host-side SCSI Parameters." Then press <Enter>.
You will need to make adjustments in the following four submenus: Peripheral Device Type, Peripheral Device Qualifier, Device Support for Removable Media, and LUN Application. Different host operating systems require different adjustments. Look at the table below to find the proper settings for your host operating system.
Table 2-2 : Peripheral Device Type Parameters Referencefor Various Operating Systems
Operating System Peripheral Device Type Peripheral Device Qualifier Device Support for Removable Media LUN Applic-ability NT 4.0 1f connected disabled All Undefined LUNs NT 5.0 3 connected enabled All Undefined LUNs NetWare 4.x 1f connected disabled All Undefined LUNs SCO Unix 5.0x 7f connected either is okay All Undefined LUNs UnixWare 2.1x 3 connected either is okay All Undefined LUNs Solaris 2.5.x/2.6 7f connected either is okay All Undefined LUNs
Table 2-3 : Peripheral Device Type Settings:
Device Type Setting No Device Present 7f Direct-access Device 0 Sequential-access Device 1 CD-ROM Device 5 Scanner Device 6 MO Device 7 Unknown Device 1f Processor Type 3
Example: Settings for Windows NT 4.0The settings for Windows NT 4.0 are provided here as an example. For the settings under other operating systems, please refer to table 2-2 above, Peripheral Device Type Parameters Reference for Various Operating Systems.
On the front panel, use t or s to select "Peripheral Device Type Parameters"; and then press <Enter>.
(For this example, we assume that there are currently no peripheral devices.)
Press t or s to choose "Unknown Device - 1f".
Press <Enter> to confirm the selection. Now that we have changed the Peripheral Device Type, let us set the Peripheral Device Qualifier. Press <Esc> to return to the sub-menus mentioned above. Use the arrow keys to scroll down to Device Qualifier., press t or s to select "Device Qualifier Connected."
The default setting is "Connected." If your Front Panel reads "Disconnected," press <ENT> and you will be prompted to change to "Connected." If your Device Qualifier setting reads "Connected,"
press <Esc> to return to the host-side SCSI submenus.
Use the t or s to select Support for Removable Media. The default setting is "Disabled." If the LCD reads "Enabled," press <Enter> and you will be prompted to accept a change. If the screen reads "Disabled," press <Esc> to return to the host-side SCSI submenus.
Press t or s to select "LUN Application"; and then press <Enter>. The default setting is "All Undefine LUN."
Press <Enter> and use t or s to select "Undefine LUN-0's."
Press <Enter> to accept. The screen should display the following message.
The RAID controller adjustments necessary to use in-band SCSI have been completed.
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