Add some more undo datafiles and increase your retention period; 900 = 5 minutes which isn't long enough :) Here's a lil blurb from the docs: Specifies (in seconds) the amount of committed undo information to retain in the database. undo_retention can be used to satisfy queries that require old undo information to rollback changes to produce older images of data blocks. A setting of 7200 = 2 hours, 10800 = 3 hours, 14400 = 4 hours, 18000 = 5 hours. The undo_retention works best if the current undo tablespace has enough space for the active transactions. If an active transaction needs undo space and the undo tablespace does not have any free space, then the system will start reusing undo space that would have been retained. This may cause long queries to fail. Be sure to allocate enough space in the undo tablespace to satisfy the space requirement for the current setting of this parameter. -----Original Message----- From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Janine Sisk Sent: Tuesday, May 25, 2010 5:22 PM To: oracle-l L Subject: ORA-1555 error with AUM already enabled A full export of my database takes far longer on AWS than it does on my old Linux server (30 minutes vs 2+ hours). During the export, I receive the following error: EXP-00056: ORACLE error 1555 encountered ORA-01555: snapshot too old: rollback segment number 1 with name "_SYSSMU1_3780397527$" too small I checked the parameters that control automatic undo management and found them to be set correctly: SQL> show parameter undo NAME TYPE VALUE ------------------------------------ ----------- ------------------------------ undo_management string AUTO undo_retention integer 900 undo_tablespace string UNDOTBS1 I tried running the export again, to see whether Oracle would have automatically adjusted something to fix the problem, but it failed again. Is this just one of those freak cases where circumstances have psyched out the automatic feature, or is there something I can do to fix it, beyond whatever the manager is doing? Clearly the immediate problem is that my rollback segments are too small, but since Oracle is managing them I hesitate to go make them bigger myself. The longer range issue is the slow performance of the virtual disk drives, which is something I haven't delved into yet. thanks, janine -- //www.freelists.org/webpage/oracle-l -- //www.freelists.org/webpage/oracle-l