How to Mirror File Systems That Cannot Be Unmounted

Use this procedure to mirror file systems that cannot be unmounted during normal system usage, such as /usr, /opt, or swap.

1. Become superuser on a node of the cluster.

2. Put the slice on which an unmountable file system resides in a single slice (one-way) concatenation.

   # metainit -f submirror1 1 1 diskslice

3. Create a second concatenation.

   # metainit -f submirror2 1 1 submirror-diskslice

4. Create a one-way mirror with one submirror.

   # metainit mirror -m submirror1

   ---

   Note -

   The metadevice name for the mirror does not need to be unique throughout the cluster.

   ---

5. Repeat Step 1 through Step 4 for each unmountable file system to be mirrored.

6. On each node, edit the /etc/vfstab file entry for each unmountable file system you mirrored.

   Replace the names in the device to mount and device to fsck columns with the mirror name.

   # vi /etc/vfstab #device        device          mount           FS      fsck    mount   mount #to mount      to fsck         point           type    pass    at boot options # /dev/md/dsk/mirror /dev/md/rdsk/mirror /filesystem  ufs     2       no      global

7. Evacuate any resource groups or device groups from the node.

   # scswitch -S -h node

   -S

   Evacuates all resource groups and device groups

   -h node

   Specifies the name of the node from which to evacuate resource or device groups

8. Reboot the node.

   # shutdown -g0 -y -i6

9. Attach the second submirror to each mirror.

   This attachment starts a sync of the submirrors.

   # metattach mirror submirror2

10. Wait for the sync of the mirrors, started in Step 9, to complete.

    Use the metastat(1M) command to view mirror status.

    # metastat mirror

11. If the disk used to mirror the unmountable file system is physically connected to more than one node (multiported), enable the localonly property of the raw disk device group for the disk used to mirror the unmountable file system.

    You must enable the localonly property to prevent unintentional fencing of a node from its boot device if the boot device is connected to multiple nodes.

    1. If necessary, use the scdidadm -L command to display the full device ID (DID) pseudo-driver name of the raw disk device group.

       In the following example, the raw disk device group name dsk/d2 is part of the third column of output, which is the full DID pseudo-driver name.

       # scdidadm -L ... 1            phys-schost-3:/dev/rdsk/c1t1d0    /dev/did/rdsk/d2 # scconf -c -D name=dsk/d2,localonly=true

       For more information about the localonly property, see the scconf_dg_rawdisk(1M) man page.

    2. Use the scconf(1M) command to enable the localonly property.

       # scconf -c -D name=rawdisk-groupname,localonly=true

       -D name=rawdisk-groupname

       Specifies the name of the raw disk device group

12. Do you intend to mirror user-defined file systems?

    • If yes, go to "How to Mirror User-Defined File Systems".

    • If no, go to "How to Create a Diskset" to create a diskset.

Example--Mirroring Unmountable File Systems

The following example shows the creation of mirror d1 on the node phys-schost-1 to mirror /usr, which resides on c0t0d0s1. Mirror d1 consists of submirror d11 on partition c0t0d0s1 and submirror d21 on partition c2t2d0s1. The /etc/vfstab file entry for /usr is updated to use the mirror name d1. Disk c2t2d0 is a multiported disk, so the localonly property is enabled.

(Create the mirror)
# metainit -f d11 1 1 c0t0d0s1
d11: Concat/Stripe is setup
# metainit -f d21 1 1 c2t2d0s1
d21: Concat/Stripe is setup
# metainit d1 -m d11
d1: Mirror is setup
 
(Edit the /etc/vfstab file)
# vi /etc/vfstab
#device        device          mount           FS      fsck    mount   mount
#to mount      to fsck         point           type    pass    at boot options
#
/dev/md/dsk/d1 /dev/md/rdsk/d1 /usr            ufs     2       no      global
 
(Reboot the node)
# scswitch -S -h phys-schost-1
# shutdown -g0 -y -i6
 
(Attach the second submirror)
# metattach d1 d21
d1: Submirror d21 is attached
 
(View the sync status)
# metastat d1
d1: Mirror
      Submirror 0: d11
         State: Okay
      Submirror 1: d21
         State: Resyncing
      Resync in progress: 15 % done
...
 
(Identify the DID name of the mirrored disk's raw
disk device group)
# scdidadm -L
...
1         phys-schost-3:/dev/rdsk/c2t2d0     /dev/did/rdsk/d2
 
(Enable the localonly property of the mirrored disk's
raw disk device group)
# scconf -c -D name=dsk/d2,localonly=true