HP-UX System Administrator's Guide: Overview

wt_round_robin
This load balancing policy selects an I/O path based on a
weighted round robin algorithm
Use the scsimgr command to specify which of the previous policies should be used
for a given device.
NOTE: Not every device supports every load balancing policy. The type of device
determines which of the previous policies you can use. For details see the following
manpages:
• scsimgr(1M)
• scsimgr_eschgr(7)
• scsimgr_esdisk(7)
• scsimgr_estape(7)
HP-UX can also automatically re-balance the loads on remaining data paths to a LUN
should one or more of those paths fail.
NOTE: Use the scsimgr command (see scsimgr(1M) for details) to set the load
balancing algorithm. An algorithm choice can be set individually for each LUN, or for
all LUNs on the server. Also, the choice can be permanently set (value retained across
reboots), or temporarily set (until the next reboot).
Device Special File Directories (and Name Formats)
Device Special Files are located in the /dev directory and many are organized in a
series of sub-directories within /dev. Two of these directories contain the persistent
device special files defining the physical disk drives on a server:
/dev/disk
Contains persistent device special files for block mode access to physical
disk devices on a server.
/dev/rdisk
Contains persistent device special files for character mode access to
physical disk devices on a server.
Within the previous directories, files have names in the format “diskN” (where “N”
is the instance number of the disk).
Examples:
/dev/disk/disk15
/dev/rdisk/disk7
An optional part of a device file name for a disk can be appended to represent disk
partition numbers. By convention, in the absence of this optional part of the device file
name the name represents an entire disk. This optional part expands the format of the
name to be diskN_p# (where p# represents the partition number, tape density, or other
information).
Examples:
64 Major Components of HP-UX