====== SVM Needs maintenace ======

  # metastat d200                                                                                                                                                                                    
    d200: Mirror
      Submirror 0: d201
        State: Needs maintenance         
      Pass: 1
      Read option: roundrobin (default)
      Write option: parallel (default)
      Size: 209682432 blocks
    d201: Submirror of d200
      State: Okay         
      Size: 209682432 blocks
      Stripe 0:
          Device    Start Block  Dbase State        Hot Spare
          vpath9c          0     No    Last Erred         

Oops! It's a one-side mirror so one can't re-sync from the other side of the mirror. File system is consistent as it can be mounted (fsck shows no errors).
SVM does not agree. 

  * Do a backup
  * Umount the file system (in this case it was /oracle)
  * Drop the mirror: metaclear -f d200
  * recreate mirror: metainit d200 -m d201
  * The maintance state is now OK:

  # metastat d200                                                                                                                                                                                    
  d200: Mirror
      Submirror 0: d201
        State: Okay         
      Pass: 1
      Read option: roundrobin (default)
      Write option: parallel (default)
      Size: 209682432 blocks
  d201: Submirror of d200
      State: Okay         
      Size: 209682432 blocks
      Stripe 0:
          Device    Start Block  Dbase State        Hot Spare
          vpath9c          0     No    Okay         

[[http://francoisbasquin.blogspot.com/2008/06/solaris-metastat-need-maintenance-state.html]]