Checkpoints and Locking
By default, an exclusive lock is not taken on the database when you take a checkpoint. Other users who are using the database at the time of the checkpoint can continue working online. During this time, transactions in progress are placed in the dump file for the database.
When you perform a roll forward, the dump files are used to restore the database to its state when the checkpoint was taken. It updates the database from journals, if the database is journaled.
The following options on the ckpdb command, however, cause an exclusive database lock to be taken:
• -l to take the checkpoint offline
• +j or -j to enable or disable journaling
If you want to continue the present journaling status, use neither journaling option.