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Sun Cluster 3.1 Software Installation Guide

How to Mirror the Global Namespace

Use this procedure to mirror the global namespace, /global/.devices/node@nodeid.

  1. Become superuser on a node of the cluster.

  2. Put the global namespace slice in a single slice (one-way) concatenation.

    Use the physical disk name of the disk slice (cNtXdYsZ).


    # metainit -f submirror1 1 1 diskslice

  3. Create a second concatenation.


    # metainit submirror2 1 1 submirror-diskslice

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


    # metainit mirror -m submirror1

    Note –

    The metadevice or volume name for the mirror must be unique throughout the cluster.

  5. Attach the second submirror to the mirror.

    This attachment starts a sync of the submirrors.


    # metattach mirror submirror2

  6. Edit the /etc/vfstab file entry for the /global/.devices/node@nodeid file system.

    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 /global/.devices/node@nodeid ufs 2 no global

  7. Repeat Step 1 through Step 6 on each remaining node of the cluster.

    Ensure that each metadevice or volume name for a mirror is unique throughout the cluster.

  8. Wait for the sync of the mirrors, started in Step 5, to complete.

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


    # metastat mirror

  9. Is the disk that is used to mirror the global namespace physically connected to more than one node (multiported)?

    • If no, go to Step 10.

    • If yes, enable the localonly property of the raw disk device group for the disk used to mirror the global namespace. 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(1M) 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. View the node list of the raw disk device group.

      Output will look similar to the following, where N is the DID number.


      # scconf -pvv | grep dsk/dN
Device group name:						dsk/d2
...
  (dsk/d2) Device group node list:		phys-schost-1, phys-schost-3
...

    3. Does the node list contain more than one node name?

    4. Remove all nodes from the node list for the raw disk device group except the node whose root disk you mirrored.

      Only the node whose root disk you mirrored should remain in the node list. 


      # scconf -r -D name=dsk/dN,nodelist=node
      -D name=dsk/dN

      Specifies the cluster-unique name of the raw disk device group

      nodelist=node

      Specifies the name of the node or nodes to remove from the node list

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

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


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

      Specifies the name of the raw disk device group

  10. Do you intend to mirror file systems other than root (/) that cannot be unmounted?

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

Example—Mirroring the Global Namespace

The following example shows creation of mirror d101, which consists of submirror d111 on partition c0t0d0s3 and submirror d121 on partition c2t2d0s3. The /etc/vfstab file entry for /global/.devices/node@1 is updated to use the mirror name d101. Disk c2t2d0 is a multiported disk, so the localonly property is enabled. 


(Create the mirror)
# metainit -f d111 1 1 c0t0d0s3
d111: Concat/Stripe is setup
# metainit d121 1 1 c2t2d0s3
d121: Concat/Stripe is setup
# metainit d101 -m d111
d101: Mirror is setup
# metattach d101 d121
d101: Submirror d121 is attached
 
(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/d101 /dev/md/rdsk/d101 /global/.devices/node@1 ufs 2 no global
 
(View the sync status)
# metastat d101
d101: Mirror
      Submirror 0: d111
         State: Okay
      Submirror 1: d121
         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
 
(Display the node list of the mirror disk's raw
disk device group)
# scconf -pvv | grep dsk/d2
Device group name:						dsk/d2
...
  (dsk/d2) Device group node list:		phys-schost-1, phys-schost-3
...
 
(Remove phys-schost-3 from the node list for the
raw disk device group)
# scconf -r -D name=dsk/d2,nodelist=phys-schost-3
 
(Enable the localonly property of the mirrored disk's
raw disk device group)
# scconf -c -D name=dsk/d2,localonly=true