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Chapter 26. Global Mirror examples 355
MSSERIAL (27131)
26.4.3 Failover from B to A volumes
Once the primary volumes fail and the application I/O stops at the primary site, the status of
the secondary volumes (B) is changed from
secondary pending to primary suspended. This is
done with the ACTION(FAILOVER) on the secondary volumes; see Example 26-18.
Example 26-18 Failover from B volume to A volume
//* ---------------------------- TSO --------- FAILOVER (3) ------ ***
//* ESTABLISH Global Copy PAIR(S) FAILOVER B -> A ***
//* ***
//* NOTE: ACTION IS NOT VALID WITH MODE(COPY) ***
//* -------------------------------------------------------------- ***
//EPAIRFO EXEC PGM=IKJEFT01
//SYSPRINT DD SYSOUT=*
//SYSTSPRT DD SYSOUT=*
//SYSTSIN DD DDNAME=SYSIN
CESTPAIR DEVN (X'3C00') +
PRIM (X'3C00' 73081 X'00' X'0C') +
SEC (X'2C00' 27131 X'00' X'0C') +
ACTION(FAILOVER) +
ONLINSEC(NO) MSGREQ(NO) CRIT(NO) +
OPTION(XD) CASCADE(NO)
CESTPAIR DEVN (X'3D00') +
PRIM (X'3D00' 73081 X'00' X'0D') +
SEC (X'2D00' 27131 X'00' X'0D') +
ACTION(FAILOVER) +
ONLINSEC(NO) MSGREQ(NO) CRIT(NO) +
OPTION(XD) CASCADE(NO)
CESTPAIR DEVN (X'3D01') +
PRIM (X'3D00' 73081 X'01' X'0D') +
SEC (X'2D00' 27131 X'01' X'0D') +
ACTION(FAILOVER) +
ONLINSEC(NO) MSGREQ(NO) CRIT(NO) +
OPTION(XD) CASCADE(NO)
The FAILOVER parameter value does not need to communicate to the primary volumes. This
parameter just changes the status of the secondary volumes to primary suspended. This
includes the creation of a change recording bit map for the B volumes, which allows the
re-synchronization at a later time when returning to the local site.
26.4.4 Check Global Mirror FlashCopy status between B and C volumes
At this stage you have to verify the FlashCopy status of each FlashCopy pair. For a detailed
discussion on this verification activity, refer to 23.7.4, “Check for valid Consistency Group
state” on page 285. In our test scenario all FlashCopy pairs were in good state, with the same
FlashCopy sequence number, and all FlashCopy pairs were in non-revertible state, so no
further corrective action had to be taken.
Note: Address all Global Mirror session commands to the Master LSS. This is the LSS that
was used when the Global Mirror START command was given