It is necessary to create the Snap Data Volume for the SnapOPC+ operation.
The formula for estimating the physical capacity of Snap Data Volume is as follows:
Physical capacity = (number of updated blocks for the copy source volume) x (safety factor)
Strictly speaking, both the number of blocks that have been updated on the Snap Data Volume and the management area used by the hardware (about 0.1% of the logical capacity) should also be taken into account before the SnapOPC+ is taken, however this can be covered by increasing the safety factor.
The number of blocks that have been updated on the copy source volume can be estimated by using updated estimation function.
The estimation can be performed by the following procedure:
Start the estimation of the update amount by configuring a monitor session on the copy source volume.
[Execution example]
> acsnap start -estimate -v ET001/0x1 Successful completion
Start transactions. Blocks that are updated by transactions will be recorded on the hardware.
After the estimation period has elapsed, check the number of blocks that have been updated.
[Execution example]
> acsnap query -estimate -v ET001/0x1 Update ------ 10M
After the estimation is completed, cancel the monitor session.
[Execution example]
> acsnap cancel -estimate -v ET001/0x1
See
Refer to the following sections for detail of commands.
