Hi
As the copy is already running there's nothing you can do. You should not open the source system to user, as it would create inconsistencies (tables are copied by alphabetic order and a user transaction could write data to tables that are already copied and some that are not copied yet).
Copying a 250 Gb client should not be an issue, even if this is a local copy that always run slower as is running on one host/db.
Remote client copy could run at an average speed of 10 MB/s, let say a local copy is running twice slower, if so it should take around 14 hours.
Since how long you copy is running ?
Few quick tips to speed up a copy.
Spend some time searching on SCN there are many post on that subject
- delete target client before copy
- exclude as many tables as possible
- start copying biggest table first (need to set option SINGLECOPY => 446485 - CC-ADMIN: Special copying options)
- raise parallelism as much as possible (increase dialog WP on target, check RFC quotas in RZ12 see attachment of note 142419 - Resource distribution for RFC and tRFC/qRFC configuration)
- if possible disable logging at DB level on target (489690 - CC INFO: Copying large production clients)
Less supported tip
- drop indexes on biggest copied table & recreate them after the copy (ideally in nologging mode)
Regards