Solaris: metastat "need maintenance" state on a SAN

After a scheduled downtime, one of our Oracle server (SunFire V240) was started slightly before the SAN (Sun StorEdge D280) was fully operational. It resulted in I/O errors and a metastat in "need maintenance" state.
(Please notice I've truncated the output for an easier reading).

# metastat d200 
d200: Mirror
    Submirror 0: d201
      State: Needs maintenance
    Pass: 1
    Read option: roundrobin (default)
    Write option: parallel (default)
    Size: 566198272 blocks (269 GB)

d201: Submirror of d200
    State: Needs maintenance
    Invoke: after replacing "Maintenance" components:
                metareplace d200 /dev/dsk/c3t600A...d0s0 
    Size: 566198272 blocks (269 GB)
    Stripe 0:
        Device                 Start Block  Dbase        State Reloc Hot Spare
        /dev/dsk/c3t600B...d0s0          0     No      Last Erred   Yes
    Stripe 1:
        Device                 Start Block  Dbase        State Reloc Hot Spare
        /dev/dsk/c3t600C...d0s0       8192     No      Last Erred   Yes
#

As you can see, it's a one-side mirror (easier when I need to consolidate multiple LUNs).
The metareplace command did not work:

# metareplace -e d200 /dev/dsk/c3t600A...d0s0 
metareplace: sdmtl114: d200: attempt to replace a component on the last running submirror
#

There are two way to clear the maintenance state: the recommended one, ... and the last chance.

The recommended way

1. Do a backup
   
2. Add another side to the mirror
   
3. When sync'd, drop the "old" side and recreate it
   
4. Once sync'd, drop the temporary side.
   

The last chance

1. Do a backup
   
2. Drop the mirror: metaclear -f d200
   
3. And recreate it: metainit d200 -m d201
   
4. The maintance state should now be cleared:
   

   
   # metastat d200 
   d200: Mirror
       Submirror 0: d201
         State: Okay
       Pass: 1
       Read option: roundrobin (default)
       Write option: parallel (default)
       Size: 566198272 blocks (269 GB)
   
   d201: Submirror of d200
       State: Okay
       Size: 566198272 blocks (269 GB)
       Stripe 0:
           Device                 Start Block  Dbase        State Reloc Hot Spare
           /dev/dsk/c3t600B...d0s0          0     No            Okay   Yes
       Stripe 1:
           Device                 Start Block  Dbase        State Reloc Hot Spare
           /dev/dsk/c3t600C...d0s0       8192     No            Okay   Yes
   # 

   
   

Of course, I'm not responsible if you loose any data. This worked for me, but has no guarantee it will work for you. However, it's rather good to know the trick.