IBM System storage DS6000 Series, Redbook

Page: 107 / 578

Chapter 9. FlashCopy interfaces
83
򐂰 Example 2: reverse a FlashCopy relationship multiple times.
It is possible to reverse a FlashCopy relationship multiple times, thus recopying the
contents of the original FlashCopy target volume multiple times back to the original source
volume. In this example the 0002:0102 was reversed once as part of example 1. Then
changes are made to data residing on volume 0002. A subsequent
reverseflash for
0002:0102 eliminates the changes made to 0002 and brings back the data from volume
0102 to volume 0002 as it was during the initial FlashCopy.
򐂰
Example 3: reestablish original FlashCopy direction, reversing again.
It is possible to reverse a FlashCopy relationship back again. In Example 3 this is shown
for the reversed FlashCopy relationship 0102:0002. Reversing it a second time and
referring to it as FlashCopy pair 0102:0002 is similar to establishing a new FlashCopy for
the volume pair 0002:0102. In this case a sequence number provided with the
reverseflash is used to identify a new FlashCopy relationship.
Reset target to contents of last consistency point using revertflash
The command revertflash can be used to reset the target volume to the contents of the last
consistency point. Like the commitflash command, this command is intended to be used in
asynchronous environments like Global Mirror environments. Before this command can be
issued, the relationship must be made revertible, either automatically as with Global Mirror, or
manually using the
setrevertible command. See Example 9-7.
Example 9-7 revertflash command example
#--- Example 1
mkflash -dev IBM.1750-13ABC2A -record -persist -seqnum 01 0001:0101
Date/Time: July 11, 2005 9:44:27 AM CEST IBM DSCLI Version: 5.0.3.134 DS: IBM.1750-13ABC2A
CMUC00137I mkflash: FlashCopy pair 0001:0101 successfully created.
mkflash -dev IBM.1750-13ABC2A -nocp -seqnum 04 0001:0104 0001:0105
Date/Time: July 11, 2005 9:44:42 AM CEST IBM DSCLI Version: 5.0.3.134 DS: IBM.1750-13ABC2A
CMUC00137I mkflash: FlashCopy pair 0001:0104 successfully created.
CMUC00137I mkflash: FlashCopy pair 0001:0105 successfully created.
lsflash -dev IBM.1750-13ABC2A 0000-0005
Date/Time: July 11, 2005 9:44:56 AM CEST IBM DSCLI Version: 5.0.3.134 DS: IBM.1750-13ABC2A
ID SrcLSS SequenceNum Timeout ActiveCopy Recording Persistent Revertible SourceWriteEnabled TargetWriteEnabled BackgroundCopy
====================================================================================================================================
0001:0101 00 1 300 Disabled Enabled Enabled Disabled Disabled Disabled Enabled
0001:0104 00 4 300 Disabled Disabled Disabled Disabled Disabled Disabled Disabled
0001:0105 00 4 300 Disabled Disabled Disabled Disabled Disabled Disabled Disabled
setflashrevertible -dev IBM.1750-13ABC2A 0001:0101
Date/Time: July 11, 2005 10:14:33 AM CEST IBM DSCLI Version: 5.0.3.134 DS: IBM.1750-13ABC2A
CMUC00167I setflashrevertible: FlashCopy volume pair 0001:0101 successfully made revertible.
revertflash -dev IBM.1750-13ABC2A 0001
Date/Time: July 11, 2005 10:14:47 AM CEST IBM DSCLI Version: 5.0.3.134 DS: IBM.1750-13ABC2A
CMUC00171I revertflash: FlashCopy volume pair 0001:0001 successfully reverted.
In Example 9-7, three FlashCopy relationships are created for one source volume:
0001:0101, 0001:0104 and 0105. The
revertflash command is executed for source 0001
and as the FlashCopy relationship 0001:0101 has the Recording and Persistent property
enabled, this command refers to this FlashCopy relationship 0001:0101. Any updates done to
volume 0101 will be overwritten.
Run new background copy for persistent FlashCopy using rmflash
Additional background copies for persistent FlashCopy relationships can be created using the
rmflash
command in combination with its
-cp
parameter. See Example 9-8 on page 84.