How to Unmirror a File System

Use this procedure to unmirror a file system that can be unmounted while the system is running. To unmirror root (/), /var, /usr, or swap, or any other file system that cannot be unmounted while the system is running. see How to Unmirror a File System That Cannot Be Unmounted.

Steps

1. Make sure that you have root privilege and that you have a current backup of all data.

2. Read Background Information for RAID 1 Volumes.

3. Verify that at least one submirror is in the Okay state.

   # metastat

4. Unmount the file system.

   # umount /home

5. Detach the submirror that will continue to be used for the file system

   For more information, see the metadetach(1M) man page.

   # metadetach d1 d10

6. Clear the mirror and remaining subcomponents.

   For more information, see the metaclear(1M)

   # metaclear -r d1

7. Edit the /etc/vfstab file to use the component detached in Step 5, if necessary.

8. Remount the file system.

Example 11–19 Unmirroring the /opt File System

# metastat d4
d4: Mirror
    Submirror 0: d2
      State: Okay        
    Submirror 1: d3
      State: Okay        
...
# umount /opt
# metadetach d4 d2
d4: submirror d2 is detached
# metaclear -r d4
d4: Mirror is cleared
d3: Concat/Stripe is cleared
(Edit the /etc/vfstab file so that the entry for /opt is changed  from d4 to the underlying slice or volume)
# mount /opt

In this example, the /opt filesystem is made of a two-way mirror named d4; its submirrors are d2 and d3, made of slices /dev/dsk/c0t0d0s0 and /dev/dsk/c1t0d0s0, 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 be repaired first.) The file system is unmounted then submirror d2 is detached. The metaclear -r command deletes the mirror and the other submirror, d3.

Next, the entry for /opt in the /etc/vfstab file is changed to reference the underlying slice. For example, if d4 were the mirror and d2 the submirror, the following line:

/dev/md/dsk/d4  /dev/md/rdsk/d4  /opt ufs  2  yes -

should be changed to:

/dev/md/dsk/d2  /dev/md/rdsk/d2  /opt ufs  2  yes -

By using the submirror name, you can continue to have the file system mounted on a volume. Finally, the /opt file system is remounted.

By using d2 instead of d4 in the /etc/vfstab file, you have unmirrored the mirror. Because d2 consists of a single slice, you can mount the file system on the slice name (/dev/dsk/c0t0d0s0) if you do not want the device to support a volume.