HP StorageWorks XP24000 for FlashCopy Mirroring Software User's Guide (T5240-96001, June 2007)

T-VOL T-VOL S-VOL
Cannot be
created
Legend
: Copy source extent
: Copy target extent
: Copy by
Version 2
Figure 14 Ex
ample of the Case When a Version 2 Relationship Cannot Be Created
Copy Modes
When you establish a relationship, Version 2 allows you to select COPY mode or NOCOPY mode.
When you select COPY mode, Version 2 copies all the data in the S-VOL to the T-VOL. This process is
called
background copying. Version 2 automatically withdraws the pair when the background copying is
complete. Note that when you select NOCOPY mode, the background copying operation will not be
performed.
If there is a request for a write operation to the space in the S-VOL from which the data is not yet copied
or a
request for a read/write operation to the space in the T-VOL to which the data is not yet copied,
Version 2 first copies the old data in the S-VOL to the T-VOL. This p rocess is called on-demand copying.
The figure below illustrates the process of on-demand copying.
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