The correct answer is: you don't need to increase /. That's because it is a static directory which seldom changes size--unless mistakes have been made. The first mistake is a spelling error during a backup: tar cvf /dev/rmt/om * (which creates a file called om in /dev, a big mistake). The second mistake is to create large test files in root's home directory. The default (not a good one at all) for root's home is / so whatever root stores in the home directory increases / usage. The 3rd mistake is badly written application programs that do not follow Unix filesystem conventions amnd store their code in /opt, /etc/opt and /var/opt, but rather create a / directory. These apps can be moved to another directory and a symbolic link made from / to the 'correct' location.
I follow Bills opinion. Parehaps it will be helpfull to create a seperate lvol for /tmp, which is often part of the /root-lvol. Or you may remove the oldest vmunix and system backupfiles from /stand.
"/" should be static. It should be reviewed why / has a decreasing available disk space. The usual culprit is the creation (by mistake) of a device file under /dev (which will now be a regular file). I've attached a script to check for regular file in /dev.
the way to increase root filesystem is to boot into single user mode, us lvextend to extend the logical volume, and then use extendfs to extend the filesystem.
cassanova is just being punished for going to desolation row
Have a look at the allocation policy of the root file system logical volume (lvol3). # lvdisplay -v /dev/vg00/lvol3 | grep Alloca
You will find it is set to: Allocation --- strict/contiguous
Contiguous means that the extents must be consecutive. Since lvol4 follows immediately after lvol3, there will be no available contiguous extents to expand lvol3 (/).
