gpadmin=# \d gp_persistent_database_node

Table "pg_catalog.gp_persistent_database_node"

Column | Type | Modifiers
----------------------------------------------+----------+-----------
tablespace_oid | oid | not null
database_oid | oid | not null
persistent_state | smallint | not null
create_mirror_data_loss_tracking_session_num | bigint | not null
mirror_existence_state | smallint | not null
reserved | integer | not null
parent_xid | integer | not null
persistent_serial_num | bigint | not null
previous_free_tid | tid | not null

Tablespace: "pg_global"

The gp_persistent_database_node table keeps track of the status of file system objects in relation to the transaction status of database objects. This information is used to make sure the state of the system catalogs and the file system files persisted to disk are synchronized. This information is used by the primary to mirror file replication process.