When you migrate V-VOL data through the host, unallocated areas of the volume might be copied as well. The used capacity of the pool increases after the data migration because the areas that were unallocated before the data migration have become allocated areas due to the migration.

To migrate the V-VOL data

1. Copy all data of V-VOLs from the source to the target.
2. Perform the operation to reclaim zero pages for each V-VOL.

   When data migration is done on a file-by-file basis, perform the operation to reclaim zero pages only if necessary.

To restore the backup data

1. Restore the V-VOL data.
2. Perform the operation to reclaim zero pages for each V-VOL.