IBM DS6000 - Manual (Page 329)

Chapter 24. Global Mirror interfaces 305
For redundancy reasons it is better to define two paths between the primary disk subsystems.
Note that the FCP ports may be shared using a SAN fabric. See Figure 24-3.
24.3.3 Establish Global Copy volume pairs
After defining the paths, you create the Global Copy volume pairs.
Figure 24-4 Establish a Global Copy pair
Figure 24-4 illustrates a Global Copy pair relationship between the primary A volume and the
secondary B volume. This relationship is maintained over the four logical paths that connect
the corresponding LSSs. These paths were defined in Example 24-9 on page 303.
Example 24-10 shows the TSO command used to define the Global Copy pair relationship.
Example 24-10 Define Global Copy pair relationship using TSO command
//* ---------------------------- TSO ------------ CREATE (2) ----- ***
//* ESTABLISH GLOBAL COPY PAIR(S) ***
//* -------------------------------------------------------------- ***
//EPAIR EXEC PGM=IKJEFT01
//SYSPRINT DD SYSOUT=*
//SYSTSPRT DD SYSOUT=*
//SYSTSIN DD DDNAME=SYSIN
CESTPAIR DEVN (X'2C01') +
PRIM (X'2C00' 27131 X'01' X'0C') +
SEC (X'3C00' 73081 X'01' X'0C') +
ONLINSEC(NO) MSGREQ(NO) CRIT(NO) +
OPTION (XD) MODE (COPY) CASCADE(NO)
OPTION(XD) indicates a Global Copy relationship. Once the command successfully ends,
Global Copy immediately does an initial copy of the primary volumes. Example 24-11 on
page 306 shows the output information from a query command to the primary volume. You
can see the pending.XD volume state, and the number of tracks out of sync, all of which is
expected for a Global Copy pair relationship that is in its initial replication phase.
LCU: 2C00
Primary
A
2C00
LCU: 3C00
Secondary
B
3C00
es
tabl
ish Global Copy pa
ir
logical paths
connecting LSSs