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356 IBM System Storage DS6000 Series: Copy Services with IBM System z
26.4.5 Create a data consistent set of B volumes
The next step is to create a set of consistent volumes. This requires a specific FlashCopy
operation, which is
fast reverse restore, FRR; see Figure 26-4.
Figure 26-4 Establish FlashCopy from last consistent C to B
This FlashCopy command uses the C volume as the source volume and the B volume as the
target volume.
Example 26-19 shows the ACTION(FRR) command parameter. In the example we use
source and target z/OS device numbers, which implies that there is host connectivity to the
secondary storage disk subsystem.
Example 26-19 Create a set of consistent B volumes
//* -------------------------------------------------------------- ***
//FCFRR EXEC PGM=IKJEFT01
//SYSPRINT DD SYSOUT=*
//SYSTSPRT DD SYSOUT=*
//SYSTSIN DD DDNAME=SYSIN
FCESTABL SDEVN(X'3E00') TDEVN(X'3C00') ACTION(FRR)
FCESTABL SDEVN(X'3F00') TDEVN(X'3D00') ACTION(FRR)
FCESTABL SDEVN(X'3F01') TDEVN(X'3D01') ACTION(FRR)
The FCESTABL command with the ACTION(FRR) parameter value does a background copy
operation that copies only the changed tracks from the C to the B volumes, those which
changed since the last Consistency Group formation. Once the background copy completes,
the FlashCopy relationship between the C and B volumes is withdrawn and ends. After that,
the C volumes are not usable and only the B volumes are now a set of data consistent
volumes.
26.4.6 Optionally create a data consistent set of D volumes
Optionally, you can create a second copy of valid data by doing a copy of the B volumes on a
set of D volumes. Example 26-20 on page 357 shows how to do this.
Global Copy
Primary
Primary
A
Primary
Primary
A
Primary
A
Primary
Primary
A
3F01
Primary
Primary
A
3F00
Tertiary
C
3E00
Primary
Primary
A
3D01
Primary
Primary
A
3D00
Secondary
B
3C00
Host
Local site
FRR
FlashCopy
2D01
2D00
2C00
Remote site
FICON
Primary