Space is allocated to thin provisioned volumes in units of pages by Dynamic Provisioning for Mainframe. Space is allocated to a TSE-VOL on a track basis inside an allocated page. Even if the pool becomes full, data updated on the CFCSE S-VOL will be copied to the T-VOL as long as the pages allocated to the TSE-VOL being used as the CFCSE T-VOL have tracks available.
When the target location is not allocated and there is no space avaliable on the T-VOL page, read and write operations cannot be performed. However, if the target location has already been allocated, read operations can be performed. When there is no space available to allocate a new page for write operations on the S-VOL, copy operations to the T-VOL fail and the relationship enters the failed state. The failed state causes all read and write operations to the T-VOL to fail. To recover from the failed state, you must release the relationship.
Even if the pool is completely full (no pages available to allocate to V-VOLs), you can create a relationship in which the T-VOL is a TSE-VOL. However, if you attempt to write to the S-VOL for the relationship, the relationship enters the failed state.