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Appendix A. Open systems operating systems specifics 349
Device Specific.(ZB)........C2D3.91A1
Device Specific.(YL)........U1.13-P1-I1/Q1
You can also print the WWPN of an HBA directly by running
lscfg -vl <fcs#> | grep Network
The # stands for the instance of each FC HBA you want to query.
Managing multiple paths
It is a common and recommended practice to assign a DS8000 volume to the host system
through more than one path, to ensure availability in case of a SAN component failure and to
achieve higher I/O bandwidth. AIX will discover a separate hdisk for each path to a DS8000
logical volume.
To utilize the path redundancy and increased I/O bandwidth, you need an additional software
layer in the AIX disk subsystem to recombine the multiple hdisks into one device.
Subsystem device driver (SDD)
The IBM Subsystem Device Driver (SDD) software is a host-resident pseudo device driver
designed to support the multipath configuration environments in IBM products. SDD resides
in the host system with the native disk device driver and manages redundant connections
between the host server and the DS8000. SDD is available for AIX 5.1, 5.2, and 5.3.
Refer to 15.2, “Subsystem Device Driver” on page 324 for download information and
installation and usage documentation.
Determine the installed SDD level
To determine whether SDD is installed, and at which level, you can use the lslpp -l
command, as shown in Example A-5.
Example: A-5 lslpp -l “*sdd*”
Fileset Level State Description
----------------------------------------------------------------------------
Path: /usr/lib/objrepos
devices.sdd.52.rte 1.5.1.2 COMMITTED IBM Subsystem Device Driver
for AIX V52
Path: /etc/objrepos
devices.sdd.52.rte 1.5.1.2 COMMITTED IBM Subsystem Device Driver
for AIX V52
Useful SDD commands
The datapath query device command displays information about all vpath devices. It is
useful to determine the number of paths to each SDD vpath device and their status. See
Example A-6.
Example: A-6 datapath query device command
{yli4642:root}/home/redbook -> datapath query device
Total Devices : 2
DEV#: 0 DEVICE NAME: vpath3 TYPE: 2107 POLICY: Optimized
SERIAL: 10522873
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