Filter
Top Products
64 Chapter 2 Overview of CCI Operations
HORCM_CMD
#dev_name dev_name dev_name
/dev/rdsk/c1t66d36s2 /dev/rdsk/c2t66d36s2
Figure 2.31 Example of Alternate Path for Command Device for Solaris Systems
2.8.6 Alternate Command Device Function
The CCI software issues commands to the command device via the UNIX/PC raw I/O
interface. If the command device fails in any way, all Hitachi TrueCopy/ShadowImage
commands are terminated abnormally, and the user cannot use any commands. Because the
use of alternate I/O pathing depends on the platform, restrictions are placed upon it. For
example, on HP-UX systems only devices subject to the LVM can use the alternate path PV-
LINK. To avoid command device failure, CCI supports an alternate command device function.
Definition of alternate command devices. To use an alternate command device, you
must define two or more command devices for the HORCM_CMD item in the
configuration definition file (see sections 2.8.3 and 2.9). When two or more devices are
defined, they
are recognized as alternate command devices.
Timing of alternate command devices. When the HORCM receives an error notification
in reply from the operating system via the raw I/O interface, the command device is
alternated. It is possible to alternate the command device forcibly by issuing an
alternating command provided by Hitachi TrueCopy (horcctl -C).
Operation of alternating command. If the command device will be blocked due to
online maintenance (e.g., microcode replacement), the alternating command should be
issued in advance. When the alternating command is issued again after completion of
the online maintenance, the previous command device is activated again.
Multiple command devices on HORCM startup. If at least one command device is
available during one or more the command devices which was described to the
configuration definition file, then HORCM will be able to start with warning message to
startup log by using available command device. The user needs to confirm that all
command devices can be changed by using horcctl -C command option, or HORCM has
been started without warning message to the HORCM start up log.
HORCM
Command
Device
TrueCopy/
ShadowImage
Command
Command
HORCM
(CCI)
Alternating
Command
Hitachi RAID
Storage System
Command
Figure 2.32 Alternate Command Device Function