We had a look at a pool today which had a raidz1 vdev consisting of 2x2TB drives and 1x1TB drive. The 1TB drive failed and was replaced with a 2TB drive; however, on resilver the pool didn’t expand. Exporting and importing didn’t work, so we tried:
# zpool online -e [poolname] [disk01] [disk02] [disk03]
…and the available capacity increased as it should.