HP StorageWorks XP Remote Web Console Software - Manual (Page 21)

ShadowImage for z/OS user guide 21
Split Type
When splitting pairs, you can also select the split type: Quick Split or Steady Split.
• When you specify Quick Split:
When the quick split operation starts, the pair status changes to V-split. You have full read/write access
to the split T-VOL (even though it is still reserved). The whole S-VOL data or differential data at that time
will be copied to the T-VOL in the background.
For information about Read/Write operations from host servers to S-VOLs and T-VOLs of SIz pairs
during quick split operations, see Table 4 .
• When you specify Steady Split:
When the steady split operation starts, the pair status changes to SP-pending. The whole S-VOL data or
differential data at that time will be copied to the T-VOL. When the steady split operation is complete,
you have full read/write access to the split T-VOL (even though it is still reserved). If you want to quickly
finish the copy operation to access the T-VOL, make the S-VOL offline before the operation.
For information about Read/Write operations from host servers to S-VOLs and T-VOLs of SIz pairs
during steady split operations, see Table 4 .
The following table shows read/write operations from the host servers to the volumes during the split pair
operation.
NOTE: Use the CSUSPEND and PPRCOPY SUSPEND commands to split SI390 volume pairs. For more
information on using PPRC commands to perform SI390 operations on the
XP128/XP1024/XP10000/XP12000, see ” Using PPRC Commands for ShadowImage ” on page 68.
Table 4 Operations from the Host Servers During the Split Pair Operation
Operations Volumes Quick Split Steady Split
Read S-VOL Both areas which are not copied and areas which are already copied can be read
as usual.
T-VOL The areas which are already copied can
be read as usual.
If the host server tries to read the area
which is not copied yet, firstly
ShadowImage for z/OS copies that area
from the S-VOL, and then the host server
will read the area after the copy
operation completes. Therefore, the result
will be the same as when the host server
reads the area which is already copied.
Cannot be read. Read processing will
finish abnormally.
Write S-VOL Write operation for the area which is already copied to the T-VOL is performed
normally.
If the host server tries to write data to the area which is not copied yet, new data will
be written after the old data is copied to the T-VOL. S-VOL data during the split
operation will therefore be copied to the T-VOL for sure.
T-VOL The areas which are already copied can
be written as usual.
If the host server tries to write data to the
area which is not copied yet, firstly
ShadowImage for z/OS copies that area
from the S-VOL, and then the host server
will write data to the area after the copy
operation completes. Therefore, the result
will be the same as when the host server
writes data to the area which is already
copied.
Cannot be written. Write processing will
finish abnormally.