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Dell EMC Solutions Enabler 9.2 SRDF Family CLI User Guide

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Planned workload switching: Concurrent SRDF/Star

About this task

A planned workload switch operation switches the workload function to one of the remote target sites, even when:

  • The original workload site is operating normally,
  • The system state is STAR Protected, or
  • The target sites are at least Connected.
NOTE:All RDF links between the 3 sites, including the RDF links for the recovery leg, must be online before you initiate the planned switch operation.

To switch the workload from the original site:

Steps

  1. Confirm the system state using the symstar query command.
  2. Stop the application workload at the current workload site, unmount the file systems, and export the volume groups.
  3. Perform the SRDF/Star halt action from the Star control host.

    To halt CG StarGrp: 

    symstar -cg StarGrp halt
    NOTE:

    If you change your mind after halting SRDF/Star, issue the halt -reset command to restart the workload site on the same Star control host.

    The halt action at the initial workload site (NewYork):

    • Disables the R1 devices,
    • Waits for all invalid tracks and cycles to drain,
    • Suspends the SRDF links,
    • Disables SRDF consistency protection, and
    • Sets the STAR mode indicators.

    The target sites transition to the Halted state, with all three sites having the data.

    Figure 1. Concurrent SRDF/Star: halted
  4. From a Star control host at the synchronous target site (NewJersey), issue the switch command to switch the workload to the synchronous target site (NewJersey). 
    symstar -cg StarGrp switch -site NewJersey

    The following image shows the resulting SRDF/Star state:

    Figure 2. Concurrent SRDF/Star: switched
  5. From a Star control host at the synchronous target site (NewJersey), issue two connect commands to:
    • Connect NewJersey to NewYork (synchronously)
    • Connect NewJersey to London (asynchronously): 
    symstar -cg StarGrp connect -site NewYork
symstar -cg StarGrp connect -site London

    The following image shows the resulting SRDF/Star state:

    Figure 3. Concurrent SRDF/Star: connected
  6. From a Star control host at the synchronous target site (NewJersey), issue two protect commands and the enable command to:
    • Protect NewJersey to NewYork
    • Protect NewJersey to London
    • Enable SRDF/Star 
    symstar -cg StarGrp protect -site NewYork
symstar -cg StarGrp protect -site London
symstar -cg StarGrp enable

    The following image shows the resulting SRDF/Star state:

    Figure 4. Concurrent SRDF/Star: protected

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