[contingencies]

You can add swap space, and there is even swap space acounting support in the kernel. Personally I don't use swap, I just buy fat amounts of RAM and allocate them to diskless worker-nodes in my clusters. As for partitioning, manual partitioning can give a slight speed advantage (if you know which filesystem you want to use, you have a long enough lived job to justify optimization, etc.), but generally you can just use http://zfsonlinux.org/ or at least LVM2 to avoid the segregation requirement entirely. In the former (ZFS) case you get arbitrary-depth COW snapshots, dynamic reallocation, transparent compression, and other types of useful options for ~free, as well. In the latter (LVM2 LV) case you get single-depth snapshots (though in theory this is improving; eg. via thin provisioning) but no dynamic resizing support (AFAIK, unless you use nonstandard filesystems).