When I list the PV's using lspv i see both vpath and hdisk names being listed. I got the info that each vpath is configured for 4 hdisks. Problem is I am not able to add either the hard disks in vpath to the existing non-rootvg. ? need to know the basics of vpath ..

Seems like you use SDD that creates vpath devices from the hdisks. The hdisks appear as often as there are paths, i.e. if you see every hdisk four times there are four paths from your server's FC adapter to the storage box. To make the best use of the multi path I/O you need to use the vpath devices for creating/extending a vg and must not use the hdisk devices. Basic SDD commands are hd2vp (to create vpath devices from hdisks) vp2hd (to remove the vpath device) and dpovgfix (if the vpath configuration got messed up).

to list out a easy displayout the vpaths maped to disk yue the following
lsvpcfg

I got this SDD related info on my AIX box



lslpp -l | grep -i sdd
devices.sdd.52.rte 1.6.0.2 APPLIED IBM Subsystem Device Driver
devices.sdd.52.rte 1.6.0.2 APPLIED IBM Subsystem Device Driver

Shockneck..
"Basic SDD commands are hd2vp (to create vpath devices from hdisks) vp2hd (to remove the vpath device) and dpovgfix (if the vpath configuration got messed up). "
I am unable to find these commands in my box... any comments on this

I got the following info from one of my colleague's

AIX 4.3 to 5.2 ...the san disk naming convension is vpath.....later version ie 5.3......it will show as hdisk

Is that the case

You need both the SDD package and the host attachment scripts. In case of ESS with FC which I assume you have this would be devices.fcp.disk.ibm2105.rte. With parallel SCSI connection replace fcp with scsi.

I am afraid not. You can convert vpath to hdisk if you don't want to use vpath devices. But SDD naming convention did not change and most likely won't change in the future as both ESS and SDD are not developed any further.