sysutils/lsof, sysutils/fuserhow to find out who keeps this device busy ?
# fstat /data
USER CMD PID FD MOUNT INUM MODE SZ|DV R/W NAME
# fstat -v /data
...
unknown file type 5 for file 13 of pid 1128
can't read vnode at 0x0 for pid 45
can't read vnode at 0x0 for pid 44
...