[OpenIndiana-discuss] how to release OS disk space?

[Dang Zhiqiang]

Hi,
Why my disk space more and more less, and how to release it?
OS: 151a9
not clone, no spanshot 
# zpool list rpool1
NAME     SIZE  ALLOC   FREE  EXPANDSZ    CAP  DEDUP  HEALTH  ALTROOT
rpool1  3.72G  3.65G  72.0M         -    98%  1.00x  ONLINE  -
# zfs list -t snapshot
no datasets available


Thanks