I was doing the 11.0 to 11.1 upgrade, and pkg told me:

pkg: Insufficent disk space available (3.16 GB)for estimated need (4.42 GB) for
Root filesystem

So I need to find another Gb and a bit from somewhere, and it happens that this box has way more swap space than it needs.

On any Solaris with ZFS root, swap is a ZFS dataset just like any other. Well, almost any other. It’s acutally a vdev, so it needs to be created with -V and a size.

$ swap -l
swapfile                  dev    swaplo   blocks     free
/dev/zvol/dsk/rpool/swap 171,2         8    12280    12280

The steps are to remove the swap space, destroy the dataset, recreate it with a smaller size, then add it again.

# swap -d /dev/zvol/dsk/rpool/swap
# zfs destroy rpool/swap
# zfs create -V 3G rpool/swap
# swap -a /dev/zvol/dsk/rpool/swap

If, like me, you have slow disks, it can take a while to intialize the swap, but that’s all you have to do. Beats messing about with swap partitions doesn’t it?