You might also consider a tool I've used before from
Storix It would let you run a backup and the rebuild your server laying out new partitions as you go. Probably better than just increasing everything everywhere. Try to keep the root filesystem and others like
/usr &
/var to only have what is critical to get the OS to boot, perhaps with backup/recovery software included.
/tmp and
/home should also be separate filesystems really, ideally on separate physical volumes (or LUNs if disk is VM or SAN provided)
I'm not sure if it is available for your OS though, but please do have a read. It is very likely and is an excellent tool, apparently written by some of those that wrote
mksysb for AIX.
I hope that this is useful,
Robin