Installation Guide and Reference

Alternate Disk Migration Installation

Alternate disk migration installation allows the user to create a copy of rootvg to a NIM client's free disk (or disks) and simultaniously perform a migration installation the Network Installation Management (NIM) environment. There are several advantages to using alternate disk migration installation over a conventional migration:

• Less downtime (the migration is performed while the system is up normally and there is no need to boot from any media).
• Quick recovery in case of migration failure.
• High degree of flexibility and customization.

Reduced downtime. The migration is performed while the system is up and functioning. There is no requirement to boot from install media, and the majority of processing occurs on the NIM master.

Quick recovery in the event of migration failure. Since you are creating a copy of rootvg, all changes are performed to the copy (altinst_rootvg). In the even of serious migration installation failure, the failed migration is cleaned up and there is no need for the administrator to take further action. In the event of a problem with the new (migrated) level of AIX, the system can be quickly returned to the pre-migration operating system by booting from the original disk.

High degree of flexibility and customization in the migration process. This is done with the use of optional NIM customization resources: image_data, bosinst_data, exclude_files, pre-migration script, installp_bundle, and post-migration script.

Requirements

Alternate disk migration installation has the following requirements:

1. Configured NIM master running AIX 5.1 or later with AIX recommended maintenance level 5100-03 or later.
2. The NIM master must have bos.alt_disk_install.rte installed in its rootvg and the SPOT which will be used.
3. The level of the NIM master rootvg, lpp_source, and SPOT must be at the same level.
4. The client (the system to be migrated) must be at AIX 4.3.3 or later.
5. The client must have a disk (or disks) large enough to clone the rootvg and an additional 500 MB (approximately) of free space for the migration. The total amount of required space will depend on original system configuration and migration customization.
6. The client must be a registered NIM client to the master.
7. The nim master must be able to execute remote commands on the client using the rshd protocol.
8. The client must have a minimum of 128 MBs of memory.
9. A reliable network, which can facilitate large amounts of NFS traffic, must exists between the NIM master and the client.
10. The client's hardware should support the level it is migrating to and meet all other conventional migration requirements.

Before performing an alternate disk migration, you are required to agree to all software license agreements for software to be installed. You can do this by specifying the -Y flag as an argument to the alternate disk migration command or setting the ADM_ACCEPT_LICENSES environment variable to yes.

Limitations

The following limitations apply to alternate disk migration installation:

• If the client's rootvg has the Trusted Computing Base option turned on, either disable it (permanently) or perform a conventional migration. TCB needs to access file metadata which is not visible over NFS.
• All NIM resources used must be local to the NIM master.
• During the migration, the client's active rootvg may experience a small performance decrease due to increased disk I/O, nfsd activity, and some CPU usage associated with alt_disk_install cloning.
• NFS tuning may be required to optimize performance.

Alternate Disk Migration Installation Usage

The alternate disk migration installation operation is used in the NIM environment, as follows

nimadm -l lpp_source -c NIMclient -s SPOT -d Targetdisks
					[ -a PreMigrationScript ] [ -b installp_bundle] [ -z PostMigrationScript]
					[ -e exclude_files] [ -i image_data ] [ -m NFSMountOptions ] [ -o bosinst_data] 
					[-P Phases] [-Y ] [ -F ] [ -D ] [ -E ] [ -V ] [ { -B | -r } ]

To run nimadm migration to target NIM client aix1, using NIM SPOT resource spot1, NIM lpp_source resource lpp1, and target disks hdisk1 and hdisk2, type the following:

# nimadm -c aix1 -s spot1 -l lpp1 -d "hdisk1 hdisk2" -Y

The -Y flag agrees to all required software license agreements for software to be installed

Alternate Disk Migration Installation Process

The nimadm command performs a migration in 12 phases. Each phase can be executed individually using the -P flag. The user should have a good understanding of the nimadm process before performing a migration in phases. The nimadm phases are as follows:

1. The master issues the alt_disk_install command to the client, which makes a copy of the rootvg to the target disks (this is Phase 1 of the alt_disk_install process). In this phase, altinst_rootvg (alternate rootvg) is created.
2. The master runs remote client commands to export all of the /alt_inst file systems to the master. The file systems are exported as read/write with root access to the master.
3. The master NFS mounts the file systems exported in Phase 2.
4. If a pre-migration script resource has been specified, it is executed at this time.
5. System configuration files are saved. Initial migration space is calculated and appropriate file system expansions are made. The bos image is restored and the device database is merged (similar to a conventional migration). All of the migration merge methods are executed and some miscellaneous processing takes place.
6. All system filesets are migrated using installp. Any required RPM images are also installed during this phase.
7. If a post-migration script resource has been specified, it is executed at this time.
8. The bosboot command is run to create a client boot image, which is written out to the client's boot logical volume (hd5).
9. All mounts made on the master in phase 3 are removed.
10. All client exports created in phase 2 are removed.
11. The alt_disk_install command is called again (phase 3 of alt_disk_install) to make final adjustments and put altinst_rootvg to sleep. The bootlist is set to the target disk (unless the -B flag is used).
12. Cleanup is executed to end the migration. The client is rebooted, if the -r flag is specified.

For more information on the nimadm command, refer to the AIX 5L Version 5.2 Commands Reference.