You can expand the capacity of a DP-VOL used as a ShadowImage pair volume.

You can expand the DP-VOL capacity used in an SI pair alone. To expand the DP-VOL capacity in a configuration where an SI pair shares the same volumes with other software, see the User Guide for the remote replication that shares the same volume with the SI pair.

Therefore, the first pair resync operation (Normal Copy or Reverse Copy) after the expansion, or the first pair split operation after the pair quick resync operation (Quick Resync or Quick Restore) will take a while to complete. The copy progress percentage might be displayed as 100% even before the copy operation is complete.

- A V-Vol to be expanded is not an external volume.
- The LDEV format is being performed on a V-Vol to be expanded.
- A pool containing a V-Vol to be expanded meets any of the following conditions:
- Normal condition
- The used capacity of the pool does not exceed the threshold.
- The pool is not being shrunk.

- A V-Vol to be expanded is a volume created on the storage systems described in Expanding the DP-VOL capacity while keeping the pair status.
- A V-Vol to be expanded is not used in a pair with the clone attribute.
- The following numbers of tables required after the expansion do not exceed the maximum number allowed on the storage system:
- The number of differential tables
- The number of pair tables

## Calculating the numbers of differential and pair tables for each pair

- The number of differential tables required for each pair.
Calculate how many differential tables are required for each pair using the following formulas:

*number-of-differential-tables-for-expansion = number-of-differential-tables-after-expansion - number-of-differential-tables-before-expansion**number-of-differential-tables-per-pair*= ceiling ((volume-capacity [KB] / 256) / 20,448)In the example, 'ceiling' refers to rounding up the value enclosed in parenthesis ( ) to the next integer.

- The number of pair tables required for each pair.
Calculate how many pair tables are required for each pair using the following formulas:

*number-of-pair-tables-for-expansion = number-of-pair-tables-after-expansion - number-of-pair-tables-before-expansion**number-of-pair-tables-per-pair*= ceiling ((*number-of-pair-tables-per-pair*/ 36)In the example, 'ceiling' refers to rounding up the value enclosed in parenthesis ( ) to the next integer.

- Verify that the following numbers do not exceed the maximum number allowed on the storage system:
- The total numbers of current pair tables and pair tables required for expanding the capacity.
- The total numbers of current differential tables and differential tables required for expanding the capacity.

You can check the numbers of differential and pair tables in the

**Local Replication**window.