Cci And The Scsi Command Interface - Hitachi VSP F1500 User And Reference Manual

The remote command device is defined using Device Manager - Storage
Navigator. For more information, see the Hitachi Universal Volume Manager
User Guide.

CCI and the SCSI command interface

When CCI commands are converted into a special SCSI command format, a
SCSI through driver that can send specially formatted SCSI commands to the
RAID storage system is needed. As a result, OS support for CCI depends on
the OS capabilities. It is necessary to use a read/write command that can
easily be issued by many UNIX/PC server platforms. For example, ioctl() can
be used for the following platforms: HP-UX, Linux, Solaris, Windows, IRIX64,
OpenVMS and zLinux.
SCSI command format used. Use a RD/WR command that can be used
with special LDEVs, since they should be discriminated from the normal
RD/WR command.
Recognition of the control command area (LBA#). The host issues
control commands through the raw I/O special file of a special LDEV. Since
the specific LU (command device) receiving these commands is viewed as a
normal disk by the SCSI interface, the OS can access its local control area.
The RAID storage system must distinguish such accesses from the control
command accesses. Normally, several megabytes of the OS control area are
used starting at the initial LBA#. To avoid using this area, a specific LBA#
area is decided and control commands are issued within this area. The
command LBA# recognized by the storage system is shown below, provided
the maximum OS control area is 16 MB.
Figure 2-4 Relationship of the special file to the special LDEV
Acceptance of commands. A command is issued in the LBA area of the
special LDEV explained above. The RD/WR command meeting this
requirement should be received especially as a CCI command. A command is
2-7
CCI software environment
Command Control Interface User and Reference Guide