How to Unmirror a File System That Cannot Be Unmounted (Command Line)

Use this task to unmirror file systems that cannot be unmounted during normal system operation, including root (/), /usr, /opt, and swap.

The high-level steps for this procedure are:

• Running the metastat(1M) command to verify that at least one submirror is in the "Okay" state

• Running the metadetach(1M) command on the mirror that contains root (/), /usr, /opt, or swap to make a one-way mirror

• For /usr, /opt, and swap: changing the file system entry in the /etc/vfstab file to use a non-DiskSuite device (slice)

• For root (/) only: running the metaroot(1M) command

• Rebooting the system

• Running the metaclear(1M) command to clear the mirror and submirrors

Example -- Unmirroring root (/)

# metadetach d0 d20
d0: submirror d20 is detached
# metaroot /dev/dsk/c0t3d0s0
# reboot
...
# metaclear -r d0
d0: Mirror is cleared
d10: Concat/Stripe is cleared
# metaclear d20
d20: Concat/Stripe is cleared

In this example, root (/) is a two-way mirror named d0; its submirrors are d10 and d20, which are made of slices /dev/dsk/c0t3d0s0 and /dev/dsk/c1t3d0s0, respectively. The metastat command verifies that at least one submirror is in the "Okay" state. (A mirror with no submirrors in the "Okay" state must first be repaired.) Submirror d20 is detached to make d0 a one-way mirror. The metaroot command is then run, using the rootslice that the system is going to boot from. This edits the /etc/system and /etc/vfstab files to remove information specifying the mirroring of root (/). After a reboot, the metaclear -r command deletes the mirror and the other submirror, d10. The last metaclear command clears submirrror d20.

Example -- Unmirroring swap

# metastat d1
d1: Mirror
    Submirror 0: d11
      State: Okay        
    Submirror 1: d21
      State: Okay        
...
# metadetach d1 d21
d1: submirror d21 is detached
(Edit the /etc/vfstab file to change the entry for swap from metadevice to slice name)
# reboot
...
# metaclear -r d1
d1: Mirror is cleared
d11: Concat/Stripe is cleared
# metaclear d21
d21: Concat/stripe is cleared

In this example, swap is made of a two-way mirror named d1; its submirrors are d11 and d21, which are made of slices /dev/dsk/c0t3d0s1 and /dev/dsk/c1t3d0s1, respectively. The metastat command verifies that at least one submirror is in the "Okay" state. (A mirror with no submirrors in the "Okay" state must first be repaired.) Submirror d21 is detached to make d1 a one-way mirror. Next, the /etc/vfstab file must be edited to change the entry for swap to reference the slice that is in submirror d21. For example, if d1 was the mirror, and d21 the submirror containing slice /dev/dsk/c0t3d0s1, the following line:

/dev/md/dsk/d1 - - swap - no -

should be changed to:

/dev/dsk/c0t3d0s1 - - swap - no -

After a reboot, the metaclear -r command deletes the mirror and the other submirror, d11. The final metaclear command clears submirrror d21.