AIX

Hi again, we have several types of backups we do here. On the workstations backups that we do every 3 months, we do 2 backups on each ones: mksysb and a TAR /.

I need to understand better what that mksysb does
and
figure out if doing both is useless where only one is enough

I am looking at ways to improve tasks and find where I can reduce unnecessary work.

An mksysb is basically a "savevg rootvg" (see man savevg). It is a backup of the core system. What makes the mksysb special is that some boot code is included if the destination is a tape so you could put the tape into another machine and restore to clone the system you have drawn the mksysb tape from. Basically the same mechanism is used by NIM (Network Install Manager), but instead of a tape a file transferred via network is used.

The mksysb mechanism is semi-intelligent as it will not backup /tmp, /var/tmp and you can additionally exclude more directories to make the system image smaller and faster to restore.

A "tar /" will backup all files on all mounted filesystems: system, application, data, everything together. You will not want to use that to restore your system.

A well designed system will have different volume groups for system (rootvg) and application and/or application data. Use an mksysb to get a bootable system image and tar/backup/savevg to get an application data backup. You will have to take a new mksysb every time you change some system settings and some regular schedule for taking data backups.

I hope this helps.

bakunin