The Virtual Target Device name cannot be edited dynamically. It MUST be removed and recreated.

1) Determine which vscsi adapter on the client LPAR is mapped to the vhost with the vtd that needs to be changed;

a) Run the following command on the client LPAR:
# lscfg -vl hdisk#

b) Note the lun ID of the disk:
hdisk0 U9119.595.0208550-V6-C2-T1-L810000000000 Virtual SCSI Disk Drive

V6 is the client LPAR ID
C2 is the adapter slot number of the LPAR
L810000000 is the LUN ID of the backing device

c) On the HMC;
a) right click on client profile
b) go to properties
c) click Virtual I/O tab, select SCSI

d) Match the client LPAR vscsi client adapter with slot#2 (as in the above example) with the remote VIO Server name, ID and slot#;

1) Example: The remote VIO Server is ID 1, remote adapter for the VIO Server is 8.
2) Login as padmin on the VIO Server and run the following command:

$ lsmap -all | more

3) Look for the vhost adapter with location code V1-C8.

4) The backing device that has lun id L810000000000 corresponds to the hdisk in the client LPAR.

2) Change the corresponding vscsi path on the client LPAR to priority 2 or power down the client LPAR to insure that no data is going across the vscsi devices.

Example:
# chpath -l hdisk0 -a priority=2 -p vscsi0
# chpath -l hdisk0 -a priority=1 -p vscsi1

3) Save the vhost mapping on the VIO Server for recreation:

$ lsmap -vadapter <vhost#>

4) Remove the VTD:

$ rmvdev -vtd <vtdName>

5) Recreate the VTD with the new name:

$ mkvdev -vdev <hdisk#> -vadapter <vhost#> -dev <vtdName>

6) Check that the paths are still enabled on the client LPAR:

# lspath

# chpath -l hdisk# -p vscsi0 -s enable

7) Change the path priorities back on the client LPAR if necessary.