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Example 2—Migrating the Primary role in a setup with multiple Secondaries

We recommend that you create RLINKs between hosts london and tokyo when setting up the RDS.


  Note   Create SRLs of the same size on the Primary and Secondary hosts.


Before migration, the configuration of the RDS looks like this:

On Primary

On Secondary

On Secondary

Host Name

displayed by the vradmin 
printrvg
command 

seattle 

london 

tokyo 

RVG

hr_rvg 

hr_rvg 

hr_rvg 

RLINKs

rlk_london_hr_rvg* 

rlk_seattle_hr_rvg* 

rlk_seattle_hr_rvg* 

rlk_tokyo_hr_rvg* 

rlk_tokyo_hr_rvg 

rlk_london_hr_rvg 

 * Indicates active RLINKs

 To migrate the Primary RVG hr_rvg to host london

  1. Stop the applications that use the Primary data volumes. For example, if the application is a file system, unmount it.
  2. Verify that the Primary RLINKs are up-to-date by using the vxrlink status command. On the Primary seattle, issue the following commands:

    # vxrlink -g hrdg status rlk_london_hr_rvg

    # vxrlink -g hrdg status rlk_tokyo_hr_rvg

    The vradmin migrate command fails if the Primary RLINKs are not up-to-date or not in the connect state. It also fails if the data volumes are active.

  3. Migrate the Primary RVG hr_rvg by typing the following command from any host in the RDS:

# vradmin -g hrdg migrate hr_rvg london

  1. If you had created RLINKs between the Secondary london and the additional Secondary tokyo, host tokyo is automatically added to the new configuration.

    Otherwise, you must manually add tokyo as a Secondary to the new Primary london. To do this, create RLINKs between london and tokyo and associate them to the respective RVGs using the following commands.

    On host london:

    # vxmake -g hrdg rlink rlk_tokyo_hr_rvg local_host=london \

    remote_host=tokyo remote_rlink=rlk_london_hr_rvg \

    remote_dg=hrdg

    # vxrlink -g hrdg assoc hr_rvg rlk_tokyo_hr_rvg

    On host tokyo:

    # vxmake -g hrdg rlink rlk_london_hr_rvg local_host=tokyo \

    remote_host=london remote_rlink=rlk_tokyo_hr_rvg \

    remote_dg=hrdg

    # vxrlink -g hrdg assoc hr_rvg rlk_london_hr_rvg


      Note   By default, the vxmake rlink command creates the RLINK with the protocol set to UDP/IP. To change the protocol to TCP/IP, see Setting the network transport protocol.


  2. Start replication to tokyo using the following command:

    # vradmin -g hrdg -f startrep hr_rvg tokyo


      Note   Ensure that the above command is run before starting the application on the new Primary london.


  3. Restart the application.

    Because the application was stopped properly before the migration, an application recovery is not required.

    By default, the vradmin migrate command enables replication from the new Primary london. To start the application before enabling replication, first, issue the vradmin pauserep command, start the application, and then resume replication.

After migration, the configuration of the RDS looks like this:

On Primary

On Secondary

On Secondary

Host Name

displayed by the command: 

vradmin printrvg

london 

seattle 

tokyo 

RVG

hr_rvg 

hr_rvg 

hr_rvg 

RLINKs

rlk_seattle_hr_rvg* 

rlk_london_hr_rvg* 

rlk_london_hr_rvg* 

rlk_tokyo_hr_rvg* 

rlk_tokyo_hr_rvg 

rlk_seattle_hr_rvg 

 * Indicates active RLINKs