An mksysb file consists of 4 parts:

You can exclude certain files/directories by using the "-e" flag and an exclude file (entries there follow the regexps for "grep"), but that is not obligatory. It is to speed up the process and make the image smaller, but you should it apply only once the process as a whole works.

Note that you have to have enough free space in /tmp to hold the boot block (use the bosboot command to find out how big that is) during backup AND restore. You can use the "-X" flag to automatically adjust the size of /tmp.

Note also, that there is a file /image.data, which records the sizes of the various LVs/FSes, which mksysb uses. It is possible to use this file to make FSes smaller in the backup (and hence the restore) than they are on the original system. This file is created by the mkszfile command and can be modified by hand to create certain results. The downside is that you are responsible for having a file which at least works - mksysb doesn't check that. If unsure create it directly prior to the mksysb run either by calling mkszfile by hand or using the "-i" flag of mksysb, which calls this command automatically.

The process of backing up a VG is - like any other backup - a relatively static process. unlike with a database, there is no "transaction log" in a filesystem and hence the backup is prone to inconsistencies if files are changing during backup. This is why it is advisable to have transactional data NOT in the rootvg and take the backup during times of minimal activity.

I hope this helps.

bakunin