Installing alternate disk migration
The nimadm command performs a migration in 12 phases.
Each phase can be executed individually using the -P flag. Before performing a migration in phases, you should have a good understanding of the nimadm process. The nimadm phases are as follows:
- 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. If a target mksysb has been specified, the mksysb is used to create a rootvg using local disk caching on the NIM master.
- 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. If a target mksysb has been specified, the cache file systems are created based on the image.data from the mksysb.
- The master NFS mounts the file systems exported in Phase 2. If a target mskysb has been specified, the mksysb archive is restored into the cache file systems created in Phase 2.
- If a premigration script resource has been specified, it is executed at this time.
- 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.
- All system filesets are migrated using installp. Any required RPM images are also installed during this phase.
- If a post-migration script resource has been specified, it is executed at this time.
- The bosboot command is run to create a client boot image, which is written to the client's boot logical volume (hd5).
- All mounts made on the master in phase 3 are removed.
- All client exports created in phase 2 are removed.
- 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). If an output mksysb has been specified, the cache is archived into a mksysb file, and made a nim mksysb resource.
- Cleanup is executed to end the migration. The client is rebooted, if the -r flag is specified.
Note: The nimadm command supports migrating several clients at the same time.