Example—Replacing a Submirror in a Mirror

The following example illustrates how to replace a submirror in an active mirror.

The specific configuration of the new volume d22 will depend on the component you are replacing. A concatenation, as shown here, would be fine to replace a concatenation, but would not be an ideal replacement for a stripe as it could impact performance.

# metastat d20
d20: Mirror
    Submirror 0: d21
      State: Okay        
    Submirror 1: d22
      State: Needs maintenance
...
# metadetach -f d20 d22
d20: submirror d22 is detached
# metaclear -f d22
d22: Concat/Stripe is cleared
# metainit d22 2 1 c1t0d0s2 1 c1t0d1s2
d22: Concat/Stripe is setup
# metattach d20 d22
d20: components are attached

The metastat command confirms that the two-way mirror d20 has a submirror, d22, in the “Needs maintenance” state. In this case, the entire submirror will be cleared and recreated. The metadetach command detaches the failed submirror from the mirror by using the -f option, which forces the detach to occur. The metaclear command clears the submirror. The metainit command recreates submirror d22, with new slices. The metattach command attaches the rebuilt submirror, and a mirror resynchronization begins automatically.

You temporarily lose the capability for data redundancy while the mirror is a one-way mirror.