Yes, but in fact it is the other way round: a carefully designed system organises data which are logically related (like, for instance, data used by one application) into the same volume group. These groups of logically related data make logical items to be backed up together, which is not surprising.


True. In fact "savevg" uses the same 4-part-layout "mksysb" does, but with the first 3 parts filled with dummy-entries. "savevg" even used to be a link to "mksysb", so this comes not as a surprise. The "mksysb"-file format is this (every part can be filled by dummy-entries):

1. boot code. Gets only written if destination file is a tape drive.
2. Installation section. contains installation commands, bosinst.data, etc.
3. TOC. A file in "inutoc" format of all the packages installed.
4. Data. The content of the volume group in backup-file-format (used to be "tar" in historic versions)

To restore a single file (directory, ...) from such a backup: always keep in mind, that the different parts are marked by a EOD on the tape. You have to skip forward to the fourth part and then use normal "restore" to pull it out of the backup-format file. IBM tape drives under AIX rewind automatically after every operation, you have to address the tape therefore with the auto-rewind feature switched off, which is done by using /dev/rmtX.1:

Code:

tctl fsf 3 /dev/rmtX.1 ; restore ...

Yes. It is also possible to boot the system with a normal boot CD and then restore from a non-bootable "mksysb"-image - for instance one which was taken to a file and later burned on CD.

Good idea.

I once heard the basic tenet of UNIX is: everything is a file. Editing these can't be so bad, can it? Whatever can be edited in a file can be scripted and automated. Try scripting one of these graphical true-colour 3-D clicky-thingies and you will instantly appreciate the old-fashioned ways. The ones, where it isn't necessary to use your mouse at 3 o'clock in the morning but a script started by "at" does that for you and mails you the outcome. But that is perhaps another issue for another thread.

I hope this helps.

bakunin