we are doing DG version 11.1.0.7 "snapshot DB" practice. Currently we have problem can NOT change. ====== procedures === SQL*Plus: Release 11.1.0.7.0 - Production on Thu Aug 18 11:28:17 2011 Copyright (c) 1982, 2008, Oracle. All rights reserved. Connected to an idle instance. SQL> startup mount; ORACLE instance started. Total System Global Area 2087780352 bytes Fixed Size 2161272 bytes Variable Size 1795163528 bytes Database Buffers 251658240 bytes Redo Buffers 38797312 bytes Database mounted. SQL> alter database convert to snapshot standby; Database altered. SQL> alter database open; alter database open * ERROR at line 1: ORA-01507: database not mounted -- //www.freelists.org/webpage/oracle-l