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These controllers interface to SCSI hard drives. They have the ability to provide fault tolerance for the connected drives and optionally provide write cache for the logical drives.
The User's Guide supplied by Compaq with each controller provides all the necessary information to install and configure the controller in a Compaq server.
Some administrator tunable parameters that can be modified to affect the behavior of the ciss driver are found in the file /etc/conf/pack.d/ciss/space.c.
UnixWare requires unique numbers (starting at zero) to be assigned to each HBA controller that is to be used in a system. The boot controller must be assigned an HBA number of 0 for the system to boot up successfully. The HBA number for each controller must be known by the system administrator in order to locate the entries that are created for the attached devices under the /dev/ directory. Each device name begins with cC, where C is the HBA number. (The boot driver, for example, is named /dev/dsk/c0b0t0d0p0.) Compaq drivers follow the ``controller order'' specified during System Configuration: the controller selected as ``first'' will be HBA 0; the controller selected as ``second'' will be HBA 1. If System Configuration has not been used to assign a controller order to a Compaq HBA controller, then an HBA number may be selected by the driver. The driver will update the unit field in the resource manager database with the selected number. Assigning the numbers using System Configuration allows HBA numbers to be selected before UnixWare is installed or has discovered the controller. For most other non-Compaq controllers, the HBA number will be assigned in the order the controller was discovered by the system. The HBA number of these controllers can be changed by editing the unit field of the resource manager using the dcu(1M)
The ciss driver enables SCSI target drivers (such as sd01) to communicate with target controllers and with logical units using the Storage Device Interface (SDI).
It is also possible for an application to access the SCSI bus subsystem directly by using the pass-through interface. See pt_open(3X).