Copy, Start change recording, When initializing a flashcopy with – IBM DS6000 User Manual
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Chapter 7. FlashCopy options
57
FlashCopy with copy option
If the original FlashCopy was established with the
copy
option (full volume copy), then the
updates that took place on the source volume since the last FlashCopy will be copied to
the target volume. Also, the updates done on the target volume will be overwritten with the
contents of the source volume.
.
Figure 7-3 Updates to the target volume caused by a refresh
When initializing a FlashCopy with
Start Change Recording
activated, a second and third
bitmap will be used to identify writes done to the source or the target volume (see Figure 7-4).
Figure 7-4 FlashCopy with Start Change Recording set
no updates in source
no updates in source
updates took place
in source volume
updates took place
in source volume
no updates in target
updates took place
in target volume
no updates in target volume
updates took place
in target volume
nothing to be
done as data
was already
copied from
source to target
and is identical
on both sides
current source
data will be
copied to target
source volume
target volume
time
Reads and writes with Start Change Recording option set
t
0
0
0
1
0
0
0
bitmap
t
t
t
t
t
t
data
0
0
z
t
t
t
t
t
t
target
data
x
0
0
0
b
write x
write y
t
x
t
y
read
read 1 read 2
before physical write to the source:
copy time-zero data from the source to the target
source
write z
t
z
0
0
1
1
0
0
a
b
write a
t
write b
t
a
bitmap
write c
c
t
time-zero data
not yet available
in target :
read it from
source.
0