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Sun Cluster Software Installation Guide for Solaris OS

ProcedureHow to Mirror File Systems Other Than Root (/) That Cannot Be Unmounted

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

Note –

This procedure provides the long forms of the Sun Cluster commands. Most commands also have short forms. Except for the forms of the command names, the commands are identical. For a list of the commands and their short forms, see Appendix A, Sun Cluster Object-Oriented Commands, in Sun Cluster System Administration Guide for Solaris OS.

  1. Become superuser.

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

    Specify the physical disk name of the disk slice (cNtX dYsZ).


    phys-schost# metainit -f submirror1 1 1 diskslice

  3. Create a second concatenation.


    phys-schost# metainit submirror2 1 1 submirror-diskslice

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


    phys-schost# metainit mirror -m submirror1
    Note –

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

  5. Repeat Step 1 through Step 4 for each remaining unmountable file system that you want to mirror.

  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.


    phys-schost# 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. Move any resource groups or device groups from the node.


    phys-schost# clnode evacuate from-node
    from-node

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

  8. Reboot the node.


    phys-schost# shutdown -g0 -y -i6

  9. Attach the second submirror to each mirror.

    This attachment starts a synchronization of the submirrors.


    phys-schost# metattach mirror submirror2

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

    Use the metastat(1M) command to view mirror status and to verify that mirror synchronization is complete.


    phys-schost# metastat mirror

  11. If the disk that is used to mirror the unmountable file system is physically connected to more than one node (multihosted), ensure that the device-group node list contains only one node and that the localonly property is enabled.

    Ensure that the device group meets the following requirements:

    • The raw-disk device group must have only one node configured in its node list.

    • The localonly property of the raw-disk device group must be enabled. The localonly property prevents unintentional fencing of a node from its boot device if the boot device is connected to multiple nodes.

    1. If necessary, use the cldevice command to determine the name of the raw-disk device group.


      phys-schost# cldevice show node:/dev/rdsk/cNtXdY
      Tip –

      If you issue the command from a node that is physically connected to the disk, you can specify the disk name as cNtXdY instead of by its full device path name.

      In the following example, the raw-disk device-group name dsk/d2 is part of the DID device name.


      === DID Device Instances ===                   

DID Device Name:                                /dev/did/rdsk/d2
  Full Device Path:                               phys-schost-1:/dev/rdsk/c1t1d0
  Full Device Path:                               phys-schost-3:/dev/rdsk/c1t1d0
…

      See the cldevice(1CL) man page for more information.

    2. View the node list of the raw-disk device group.


      phys-schost# cldevicegroup show dsk/dN

      Output looks similar to the following for the device group dsk/d2:


      Device Group Name:                              dsk/d2
…
  Node List:                                      phys-schost-1, phys-schost-3
…
  localonly:                                      false

    3. If the node list contains more than one node name, remove all nodes from the node list except the node whose root disk you mirrored.

      Only the node whose root disk you mirrored should remain in the node list for the raw-disk device group.


      phys-schost# cldevicegroup remove-node -n node devicegroup
      -n node

      Specifies the node to remove from the device-group node list.

    4. Enable the localonly property of the raw-disk device group, if it is not already enabled.

      When the localonly property is enabled, the raw-disk device group is used exclusively by the node in its node list. This usage prevents unintentional fencing of the node from its boot device if the boot device is connected to multiple nodes.


      phys-schost# cldevicegroup set -p localonly=true devicegroup
      -p

      Sets the value of a device-group property.

      localonly=true

      Enables the localonly property of the device group.

      For more information about the localonly property, see the cldevicegroup(1CL) man page.

Example 4–4 Mirroring File Systems That Cannot Be Unmounted

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. Device c2t2d0 is a multihost disk, so the localonly property is enabled.


phys-schost# metainit -f d11 1 1 c0t0d0s1
d11: Concat/Stripe is setup
phys-schost# metainit d21 1 1 c2t2d0s1
d21: Concat/Stripe is setup
phys-schost# metainit d1 -m d11
d1: Mirror is setup
phys-schost# 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
…
phys-schost# clnode evacuate phys-schost-1
phys-schost# shutdown -g0 -y -i6
phys-schost# metattach d1 d21
d1: Submirror d21 is attached
phys-schost# metastat d1
d1: Mirror
      Submirror 0: d11
         State: Okay
      Submirror 1: d21
         State: Resyncing
      Resync in progress: 15 % done
…
phys-schost# cldevice show phys-schost-3:/dev/rdsk/c2t2d0
…
DID Device Name:                                /dev/did/rdsk/d2
phys-schost# cldevicegroup show dsk/d2
Device Group Name:                              dsk/d2
…
  Node List:                                      phys-schost-1, phys-schost-3
…
  localonly:                                      false
phys-schost# cldevicegroup remove-node -n phys-schost-3 dsk/d2
phys-schost# cldevicegroup set -p localonly=true dsk/d2
Next Steps

To mirror user-defined file systems, go to How to Mirror File Systems That Can Be Unmounted.

Otherwise, go to Creating Disk Sets in a Cluster to create a disk set.

Troubleshooting

Some of the steps in this mirroring procedure might cause an error message similar to metainit: dg-schost-1: d1s0: not a metadevice. Such an error message is harmless and can be ignored.