Upgrade EMC powerpath on VIO server issues (mapping issue)

[Database Administrator]

Hi,

Today I ran into the following issue :

In order to update the EMC Powerpath software on a VIO server, I need to
remove all mappings.
Restoring my mappings with the same VIO LUN id seems impossible, as the
previous numbering was not contigious and the LUN id is assigned by IOS when
issueing the mkvdev command (no way to assign one myself). So basicly I can
map all devices to the corresponding vhosts, but I cannot be sure they will
use the same LUN is.
This is not a problem in most cases, but it is when the device is used as a
boot device. A change in the bootlist for VIO clients will be necessary.
This is something I would like to do without.

As it's not likely I'm the first to encounter this issue, I'm curious what
work-arounds others have come up with.
Thanks for the help!

Regards,
Mark

[colinpearse]

You could use dummy entries as place setters, eg.

mkvdev -vdev hdisk10 -vadapter vhost5 -dev vdisk1
mkvdev -f -vdev hdisk10 -vadapter vhost5 -dev dummy1
mkvdev -f -vdev hdisk10 -vadapter vhost5 -dev dummy2
mkvdev -f -vdev hdisk10 -vadapter vhost5 -dev dummy3
mkvdev -vdev hdisk11 -vadapter vhost5 -dev vdisk2
rmvdev -vtd dummy1
rmvdev -vtd dummy2
rmvdev -vtd dummy3

will create LUNs of 0x81 and 0x85.

A bit messy but at least no actions on the VIOCs (apart from ensuring there's no disk access) are necessary since lscfg -vl hdisk* will show the correct LUNs (assuming you have the patch that ensure hdisk access does not hang when the disks are unmapped).