Rollback/Undo segments are not written from beginning to end. Blocks in an undo segment are reused, perhaps by the original segment, perhaps 'stolen' by another segment or deallocated. I've never done any formal testing (if anyone has, please correct me), but it is logical to me that undo i/o patterns are similar to data/index segments. It would not suprise me if the i/o pattern of temp tablespaces are closer to data/index/undo than redo. Redo is written from beginning to end. Daniel Fink "Nelson, Allan" wrote: > You should also separate rollback segments and temp space as they have > markedly different use patterns as opposed to data and index segments. > Rollback segments tend to be written from beginning to end and over > again and temp also tends to be sequential type i/o > > Allan ---------------------------------------------------------------- Please see the official ORACLE-L FAQ: http://www.orafaq.com ---------------------------------------------------------------- To unsubscribe send email to: oracle-l-request@xxxxxxxxxxxxx put 'unsubscribe' in the subject line. -- Archives are at //www.freelists.org/archives/oracle-l/ FAQ is at //www.freelists.org/help/fom-serve/cache/1.html -----------------------------------------------------------------