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Sun Cluster Software Installation Guide for Solaris OS

Example of How to Manage a Failover or Switchover

This section describes how to provoke a switchover and how the application is transferred to the secondary cluster. After a switchover or failover, update the DNS entries. For additional information, see Guidelines for Managing a Failover or Switchover.

This section contains the following procedures:

ProcedureHow to Provoke a Switchover

Steps

  1. Change the primary cluster to logging mode.


    nodeA# /usr/opt/SUNWesm/sbin/sndradm -n -l lhost-reprg-prim \
/dev/vx/rdsk/devicegroup/vol01 \
/dev/vx/rdsk/devicegroup/vol04 lhost-reprg-sec \
/dev/vx/rdsk/devicegroup/vol01 \
/dev/vx/rdsk/devicegroup/vol04 ip sync

    When the data volume on the disk is written to, the bitmap volume on the same device group is updated. No replication occurs.

  2. Confirm that the primary cluster and the secondary cluster are in logging mode, with autosynchronization off.

    1. On nodeA, confirm the mode and setting:


      nodeA# /usr/opt/SUNWesm/sbin/sndradm -P

      The output should resemble the following:


      /dev/vx/rdsk/devicegroup/vol01 ->
lhost-reprg-sec:/dev/vx/rdsk/devicegroup/vol01
autosync:off, max q writes:4194304,max q fbas:16384,mode:sync,ctag:
devicegroup, state: logging

    2. On nodeC, confirm the mode and setting:


      nodeC# /usr/opt/SUNWesm/sbin/sndradm -P

      The output should resemble the following:


      /dev/vx/rdsk/devicegroup/vol01 <-
lhost-reprg-prim:/dev/vx/rdsk/devicegroup/vol01
autosync:off, max q writes:4194304,max q fbas:16384,mode:sync,ctag:
devicegroup, state: logging

    For nodeA and nodeC, the state should be logging, and the active state of autosynchronization should be off.

  3. Confirm that the secondary cluster is ready to take over from the primary cluster.


    nodeC# /usr/sbin/fsck -y /dev/vx/rdsk/devicegroup/vol01

  4. Switch over to the secondary cluster.


    nodeC# scswitch -Z -g nfs-rg
Next Steps

Go to How to Update the DNS Entry.

ProcedureHow to Update the DNS Entry

For an illustration of how DNS maps a client to a cluster, see Figure 6–6.

Before You Begin

Ensure that you completed all steps in How to Provoke a Switchover.

Steps

  1. Start the nsupdate command.

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

  2. Remove the current DNS mapping between the logical hostname of the application resource group and the cluster IP address, for both clusters.


    > update delete lhost-nfsrg-prim A
> update delete lhost-nfsrg-sec A
> update delete ipaddress1rev.in-addr.arpa ttl PTR lhost-nfsrg-prim
> update delete ipaddress2rev.in-addr.arpa ttl PTR lhost-nfsrg-sec
    ipaddress1rev

    The IP address of the primary cluster, in reverse order.

    ipaddress2rev

    The IP address of the secondary cluster, in reverse order.

    ttl

    The time to live, in seconds. A typical value is 3600.

  3. Create a new DNS mapping between the logical hostname of the application resource group and the cluster IP address, for both clusters.

    Map the primary logical hostname to the IP address of the secondary cluster and map the secondary logical hostname to the IP address of the primary cluster.


    > update add lhost-nfsrg-prim ttl A ipaddress2fwd
> update add lhost-nfsrg-sec ttl A ipaddress1fwd
> update add ipaddress2rev.in-addr.arpa ttl PTR lhost-nfsrg-prim
> update add ipaddress1rev.in-addr.arpa ttl PTR lhost-nfsrg-sec
    ipaddress2fwd

    The IP address of the secondary cluster, in forward order.

    ipaddress1fwd

    The IP address of the primary cluster, in forward order.

    ipaddress2rev

    The IP address of the secondary cluster, in reverse order.

    ipaddress1rev

    The IP address of the primary cluster, in reverse order.