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/usr/lpp/bos/README.PARTITION_INSTALL from AIX 5L Product


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This document describes key features and limitations associated with
the preparation of non-partition systems to enter the pSeries 690 partition
(also known as LPAR) environment.  For complete instructions on initial
installation and partition management, please refer to the the following
official publication: "AIX Installation in a Partition Environment."  For
any other questions or issues, please contact IBM AIX support or your
local marketing representative.






The utilities described in this README have been designed to simplify the
transition of existing systems from standalone configuration to partitioning.
Please note that the user could accomplish everything these utilities do
using manual AIX commands - the point of these utilities is to make this
process streamlined and convenient. Also, the several functions have been
added to the alt_disk_install utility to aid installation in a partition


Another option is to install LPARS through the alt_disk_install utility.
A user can clone the rootvg from the current system to a target disk. That
disk can then be allocated as the boot disk (rootvg) for an LPAR. To facilitate
this function, a new flag has been added to the alt_disk_install utility: "-O".
The "-O" flag performs the equivalent of "devreset" (device reset.. see bellow)
on the target disk (there is no impact to the current rootvg).

# /usr/sbin/alt_disk_install -O -B -C hdisk1

Note: You should make sure that all required device support for the
target partition is first installed on the current system or installed
through alt_disk_install functions.

After the newly installed disk (altinst_rootvg) is allocated to the target
partition using HMC functions, the bootlist should be setup in SMS menus
(multiboot menu) with the first available boot device pointing to the newly
installed disk.  After the initial boot from the newly installed disk,
the partition will not have any user defined device configuration (i.e.
networking, console, maxuproc, etc). There are two new alt_disk_install
functions to assist the user in configuring the newly installed LPAR:

1. If the "-O" flag is specified, the target altinst_rootvg will not
retain its console configuration. Therefore, the user will be prompted
to configure the system console during the initial boot from the target
disk. If the target console (the console of the system that will boot from
the target disk) is known during alt_disk_install installation, it can
be specified with the "-c <console device>" flag. NOTE: if the "-O" flag
is not specified, the "-c" flag is ignored.

Example: To set "/dev/tty0" as the console during device reset install
         to hdisk1:
# alt_disk_install -BCO -c /dev/tty0 hdisk1

Example: To set "/dev/lft2" as the console during device reset install
         to hdisk1:
# alt_disk_install -BCO -c /dev/tty0 hdisk1

2. It is possible to specify a customization script during a device
reset install with the "-x <config script>" flag. The customization
script will be copyed into altinst_rootvg and executed from inittab
immediately after /etc/rc (before networking and most other functions
are started). This gives the user an opportunity to automaticly
configure networking and any other device attributes on the target
partition.  Otherwise, the user will have to login to the newly
installed partition and configure devices manually.  The "-x" flag
applies to alt_disk_install clone, mksysb, and sleep.

# cat /tmp/lpar1.cfg
# Setup networking
/usr/sbin/mktcpip -h lpar1  -a -m \
 -i en0 -n  -d -g
# Setup maxuproc
/usr/sbin/chdev -l sys0 -a maxuproc=900

# alt_disk_install -B -CO -x /tmp/lpar1.cfg -c /dev/tty0 hdisk1

Alt_disk_install and Dynamic Partitioning
It is possible, on a system that supports dynamic LPAR (dynamic logical
partitioning), to dynamically add an adapter with disks to a running LPAR.
A new rootvg can then be installed to these added disks using
alt_disk_install (clone or mksysb). There are a few flags to keep in
mind if running alt_disk_install with dynamically added target disks
on an LPAR system:

  1. If the target disk will be used to boot an LPAR other then the
     one where the operation is being executed, the "-O" (device
     reset) flag should be used.

  2. The "-B" flag should be added to prevent "bootlist" from being
     executed.  A general limitation of dynamically added disks is
     that you can not specify them as a boot device (before an initial
     reboot).  If you are attempting to boot an LPAR from dynamically
     added disks, the bootlist should be set in SMS menus.

  3. Dynamically added disks will not appear bootable to the operating
     system (before an initial reboot).  The user will need to verify
     that the newly added adapter and disks are bootable and run
     alt_disk_install with the "-g" (ignore bootability checks) flag.

Please see the alt_disk_install man page and the "AIX 5.1 Installation
Guide" for a full description of alt_disk_install functionality.


The function of devreset (full path /usr/sbin/devreset) is to rebuild
the device ODM database and reset all devices to default configurations.
devreset does this by rebuilding all Cu* (Customized Device Attributes) in
/etc/objerepos and deleting non-standard /dev special files.  devreset
asks for interactive confirmation before making any changes (unless the Force
option is invoked), and the old device attributes and special files
are backed-up in a save directory (see -A and -R flags bellow).

** WARNING: Running devreset on a live system can result in process **
** disruption.  You must halt the system immediately after devreset **
** completes.                                                       **

# devreset

Why use devreset to reset all devices ?
There may be several reasons, but the major one is in the context of
partitioning.  The best way to illustrate its functions is by example:
Lets say that you have a system installed at AIX 5.1.  The rootvg
disk (or disks) are hot-plug (removable), and you would like to
move this disk from the current system to another system, so that the target
system can boot from this rootvg.  You have installed all the required
devices support and made sure the systems use the same kernel (lets say
MP), but there is one more problem.  When the target system comes up
from the moved disk, all of the old device entries and attributes
will still be there !  This can cause various issues down the road.
devreset solves this problem by removing all device entries and
attributes (a few attributes like rootvg LVM are not removed) so the
target system comes up with basicly a new device slate.  This can be
especially useful in the partitioning environment, where the user may wish to
switch boot disks or would like to move a disk to a new partition (physically
or logically).

A Few devreset Issues:
Before running devreset, it is *strongly* recommended that all non essential
functions are stopped. It is also a recommended that a system backup of
the OS is made (for example: mksysb).  Here are a few notes of concern:

1. Make sure you run "bootlist" before running devreset and set it to
the disk you wish the current system to boot from next. After running
devreset, you may not be able to run "bootlist" because the device
ODM definitions for the disks and other devices will be removed.

2. After running devreset, the system will be mostly unusable and should
be haled or rebooted.

3. All device configurations will be reset and may need to be reconfigured
(for example: networking parameters).

4. During the the first boot from a devreset disk, the user will be
prompted to configure the console (by pressing 1 or F1).  This is
normal and expected.

5. The user may want to search /etc/inittab and disable any gettys
that are running for devices that will not exist on the target system.

6. It may be a good idea to clear out the old hardware errpt so there
is not confusion on the target system.  The command to do this is
/usr/bin/errclear -dH 0.

7. Before moving the disk (physically or logically), make sure all device driver
support is installed for any new devices on the target system.  An easy
way to do this is to install ALL existing device support from AIX 5.1 base
level media (see -S flag for partition_ready).

* devreset arguments *

-A <directory> Flag.
Use alternate save directory.  By default, devreset will save the current
device configurations and special files in /tmp/devsave.  However,
you can specify your own save directory with this flag.  This directory
must be local to the system.  devreset attempts to calculate and expand,
if needed, the space for the save/backup directory.  Usually, the
save directory utilizes 1 to 2 megs.

# mkdir /usr/odmsave
# devreset -A /usr/odmsave

-D Flag.
Turns tracing on for all devreset functions.  This flag is used to
debug the devreset script itself and should be rarely used by the

-F Flag.
Force, do not verify or confirm.  Normally, devreset prompts you for
confirmation.  However, if there is a need to skip this confirmation,
the Force flag may be employed.

-R Flag.
Recover from previously saved directory. The default save directory
is /tmp/devsave.  The -S Flag can be used in conjunction with the -A flag.
WARNING: Be sure you have specified a valid backup directory. Restoring
invalid device files can cause system corruption or other problems.
No interactive confirmation is performed for this function.

# devreset -A /usr/odmsave -R

-S Flag.
Save current configuration only. No device attributes are altered.
The default save directory is /tmp/devsave.  The -S Flag can be used
in conjunction with the -A flag.

# devreset -S

Document information

More support for: AIX family

Software version: 530

Operating system(s): AIX

Reference #: 530readmea1c1ee7csr_

Modified date: 01 May 2008

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