Uninstalling powerpath when your rootvg resides on a SAN LUN, is not so easy, because you can’t install concurrently the MPIO disk driver fileset, with the one you’re using with powerpath ! And you won’t be able to uninstall the latter (in order to install MPIO support for your disks), unless you wanna play with the ODM.

But first things first :

 

Unconfigure powerpath

# powermt unmanage dev=all

PS : on some older versions (like 5.3 SP1), the argument « all » is not valid, you will need to specify each volume
specifically.
If you encounter this message (because you have open VG’s on the disks), don’t worry, the unmanage option will be active for the next reboot:

 # powermt unmanage dev=hdiskpower11

Cannot remove device that is in use: hdiskpower11
Device(s) will be unmanaged on Reboot.

If not done yet, unmanage your rootvg hdisk and reboot to get rid of all powerpath managed stuff:

# pprootdev off
# shutdown -Fr

Uninstall powerpath

Now we can uninstall powerpath:

# installp -u EMCpower
[..]
Installation Summary
--------------------
Name Level Part Event Result
-------------------------------------------------------------------------------
EMCpower.encryption 5.5.0.5 USR DEINSTALL SUCCESS
EMCpower.migration_enabler 5.5.0.5 USR DEINSTALL SUCCESS
EMCpower.mpx 5.5.0.5 USR DEINSTALL SUCCESS
EMCpower.base 5.5.0.5 USR DEINSTALL SUCCESS
#

Install MPIO… Failure

As I said, you can’t have EMC.Symmetrix.fcp.rte and EMC.Symmetrix.fcp.MPIO.rte together on the same system, as you can see below when I try  to install it:


FAILURES
--------
 Filesets listed in this section failed pre-deinstall verification
 and will not be removed.

Dependency Failures
 (Deinstall Operation)
 ---------------------
 SELECTED FILESETS: The following is a list of filesets that you asked to
 remove. They cannot be removed until all of their dependent filesets
 are also removed. See subsequent lists for details of dependents.

EMC.Symmetrix.aix.rte 6.0.0.0 # EMC Symmetrix AIX Support So...

INSTALLED DEPENDENTS: The following filesets are dependents of one or more
 of the selected filesets listed above. These must be removed before
 or with the filesets that you selected. To remove these dependents with
 the selected filesets, specify the option to automatically remove dependent
 software (-g flag).

EMC.Symmetrix.fcp.rte 6.0.0.0 # EMC Symmetrix FCP Support So...

<< End of Failure Section >> 

–> When you uninstall powerpath, the device driver is still in use for your disks. But you can’t install the latter when the former is still present . How to manage that ?

Clean up a bit

I like to have a clean and simple configuration  before starting this kind of operation : I delete all hdisks (before this step you need to umount FS and varyoff vgs , of course) :

# lsdev -cdisk |awk '{print "rmdev -dl "$1}' |ksh
 Method error (/etc/methods/ucfgdevice):
 0514-062 Cannot perform the requested function because the
 specified device is busy.
 hdisk1 deleted
 hdisk2 deleted
# lspv
 hdisk0 00f688f5a829fc18 rootvg active

The problem is that the rootvg is in use, and you cannot delete it , hence you cannot uninstall the symmetrix.fcp.rte package.

So we have to find another way, which is modifying the rootvg’s hdisk’s ODM entry:

ODM modification

# lsdev -c disk
hdisk0  Available 10-T1-01 EMC Symmetrix FCP VRAID
# odmget -q "name=hdisk0" CuDv
CuDv:
name = "hdisk0"
status = 1
chgstatus = 2
ddins = "scsidisk"
location = "10-T1-01"
parent = "fscsi0"
connwhere = "11"
PdDvLn = "disk/fcp/SYMM_VRAID"

First we need to backup the definition in a text file, then backup the CuDv base :

# odmget -q "name=hdisk0" CuDv > /tmp/hdisk0.odm
# cp /etc/objrepos/CuDv /etc/objrepos/CuDv.bak

Let’s edit the text file in order to change the disk’s definition to the standard no-driver « MPIO Other FC SCSI Disk Drive » definition (if you don’t have perl installed, just edit manually the file, changing the line PdDvLn = [your disk driver] by PdDvLn = « disk/fcp/mpioosdisk ») :

# perl -pi -le 's/disk\/fcp\/SYMM_VRAID/disk\/fcp\/mpioosdisk/g' /tmp/hdisk0.odm

Now we erase the disk’s definition in its ODM entry which is still in my case « EMC Symmetrix FCP VRAID » :

 # odmdelete -q "name=hdisk0 and PdDvLn=disk/fcp/SYMM_VRAID" -o CuDv
 0518-307 odmdelete: 1 objects deleted.

We load the modified ODM entry into the ODM :

# odmadd   /tmp/hdisk0.odm

Verification :

# lsdev -cdisk
hdisk0 Available 10-T1-01 MPIO Other FC SCSI Disk Drive

Ok so the disk is no longer recognized as a symmetrix disk, we should be able to uninstall the driver !

Uninstall FCP driver

In my case I had an extra problem concerning this step :

# installp -u EMC.Symmetrix.fcp.rte
 +-----------------------------------------------------------------------------+
 Pre-deinstall Verification...
 +-----------------------------------------------------------------------------+

[...]

1 Total to be deinstalled

installp: bosboot verification starting...
installp: An error occurred during bosboot verification processing.

Actually my /dev/ipldevice was missing, I had to recreate it :

# ls -ltr /dev/ipl*
 crw-rw---- 2 root system 10, 1 May 15 14:29 /dev/ipl_blv
 # ln -f /dev/rhdisk0 /dev/ipldevice 

then I re-ran the uninstallation :

# installp -u EMC.Symmetrix.fcp.rte
 +-----------------------------------------------------------------------------+
 Pre-deinstall Verification...
 +-----------------------------------------------------------------------------+
 Verifying selections...done
 Verifying requisites...done
 Results...

[..]

installp: bosboot process completed.
 +-----------------------------------------------------------------------------+
 Summaries:
 +-----------------------------------------------------------------------------+

Installation Summary
 --------------------
 Name Level Part Event Result
 -------------------------------------------------------------------------------
 EMC.Symmetrix.fcp.rte 6.0.0.0 ROOT DEINSTALL SUCCESS
 EMC.Symmetrix.fcp.rte 6.0.0.0 USR DEINSTALL SUCCESS 

MPIO installation (again)

OK so now we should be able to install the MPIO supported driver :

Installation Summary
--------------------
Name                        Level           Part        Event       Result
-------------------------------------------------------------------------------
EMC.Symmetrix.fcp.MPIO.rte  6.0.0.0         USR         APPLY       SUCCESS
EMC.Symmetrix.fcp.MPIO.rte  6.0.0.0         ROOT        APPLY       SUCCESS

Be sure to run bosboot command and verify your bootlist, before rebooting  just in case…

Now we can reboot the server and check with lspath and lspv that our disks are now managed by MPIO!

Links

Special Thanks to http://unixadmin.free.fr/?p=179

http://www-01.ibm.com/support/docview.wss?uid=swg21307030

http://unixadmin.free.fr/?p=185

EMC² Powerpath official Documentation 

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Uninstall powerpath on a Boot from SAN configuration and get back to MPIO
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