If you are using vxvm, you may have issues when you try to unconfigure a disk

root@techsupport2 # cfgadm -c unconfigure c1::dsk/c1t3d0
cfgadm: Component system is busy, try again: failed to offline:
    Resource             Information      
----------------       -------------------------
/dev/dsk/c1t3d0   Device being used by VxVM

“cfgadm unconfigure” command fails here.
The way to resolve this is to disable the disks path from DMP control. Since there is only one path to this disk, the “-f” (for force) option needs to be used:
root@techsupport2 # vxdmpadm -f disable path=c1t3d0s2
root@techsupport2 # vxdmpadm getsubpaths
NAME         STATE[A]   PATH-TYPE[M] DMPNODENAME  ENCLR-NAME   CTLR   ATTRS
================================================================================
c1t6d0       ENABLED(A)   -          disk_0       disk         c1       -
c1t3d0       DISABLED(M)   -          disk_1       disk         c1       -
c1t0d0s2     ENABLED(A)   -          disk_2       disk         c1       -
c1t1d0       ENABLED(A)   -          disk_3       disk         c1       -
c3t47d0      ENABLED(A)   -          sun35100_0   sun35100     c3       -
c3t47d1      ENABLED(A)   -          sun35100_1   sun35100     c3       -
c3t47d2s2    ENABLED(A)   -          sun35100_2   sun35100     c3       -
c3t47d3s2    ENABLED(A)   -          sun35100_3   sun35100     c3       -

You can see the path now disabled from DMP.
root@techsupport2 # cfgadm -c unconfigure c1::dsk/c1t3d0

Now you can unconfigure the disk