One of the other DBA's I work with has been trying to debug a rollback problem. Here is the issue:

An application keeps getting an Ora 1555 - Snapshot to old error. We have copied the application and DB to a test machine for debugging purposes. Only one user is using the application and db. We have experimented numerous times with increasing the rollback segments/extent sizes to eliminate the error. Currently, we are up to 4 rollback segments totaling 600meg in space. Initial/next extents are 31 meg each. The database itself is only 300 meg. We are monitoring the undo(header) in v$waitstat. It is always between 1-5. The wraps in v$rollstat is small (1-5), the extends in v$rollstat is usually 1-5. We can't seem to get rid of the error message. We are at a loss. Does anyone have any suggestions? One other thing. The process(application) will only use one rollback segment at a time. The other three remain unused. It doesn't use the same one everytime. As we start and stop the application, Oracle ramdonly chooses the rbs to use.

Thanks.