This morning we had our production 10.2.0.4 database come to practically a grinding halt with lots of I/O requests in Grid. running ADDM and ASH reports, there were, at first, problems with Segments that needed to be tuned. Then the next ADDM reports talked about "read by other session" events being 100% the major problem. After looking through Oracle Support and more and more help desk calls coming in, we decided to bounce the database. This, of course, solved our problem. I don't really understand what "read by other session" events are, so if someone can clarify that, that would be helpful. From what i read, they are memory waits for the data blocks in the buffer cache. Different logins requesting the same blocks in memory... i think. Even if that's right, i guess i still don't really understand what that means. The other thing that i'd really like to know, if we ever encounter this again since we don't really know how it happened, what other options do i have instead of bouncing the database? Flushing the buffer cache and SGA? Killing peoples session that i see in ASH reports that have these "read by other session" wait events? Thanks for any replies! Lyall