I’m coming from Ubuntu, and I kept quite a bit of things in my non-home directories. The suggestion from the openSUSE installation had a root size of 20GB and the remaining was for the /home directory - about 450 or so GB.
From experience, what size/percentage do you all allocate for your root directory?
20GiB is a sensible recommendation when the disk is large enough, I believe the installer will scale down and even drop back to a single partition as space gets tighter. Currently I have allocated 24GiB for /. Since this is but a tiny fraction of the disk, it’s nothing.
If you have large files, e.g. large MySQL databases, large VM images, you might want to make sure they are put in a partition with enough space.
Most software is installed in /usr. Some packages have used /opt eg) KDE3, or /srv.
/home should be reserved for private user data and settings. That makes backup and upgrades much simpler.
Personally I separate out data, and like to keep read-mostly partitions like /usr relatively fuller, and separate from heavy write areas like /var, which benefit from large proportion of free blocks to allocate. There’s an advantage in robustness, faster fsck times, small benefit in performance (less seeking, keeping heavily used stuff in hot areas of disk), at small cost of complexity of management (as splitting stuff up, means areas can be filled).
In fstab(5) I use an entry to transparently move a directory used for web proxy (/etc/fstab) :
/work/cache/wwwoffle /var/spool/wwwoffle auto bind 0 0
Using bind mount similarly would let you put /opt/dynamips/images into a partition which you either back up frequently, or one you ignore depending on the nature of the data.