Identify Sessions with High Disk Activity

Sessions ordered by Block Changes

set linesize 120
col os_user format a10
col username format a15
select OSUSER os_user,
       username,
       PROCESS pid,
       ses.SID sid,
       SERIAL#,
       PHYSICAL_READS,
       BLOCK_CHANGES
  from v$session ses,
       v$sess_io sio
 where ses.SID = sio.SID
   and username is not null
   and status='ACTIVE'
   and username != 'SYS'
 order by block_changes desc
/

Sample Output:

OS_USER    USERNAME        PID                 SID    SERIAL# PHYSICAL_READS BLOCK_CHANGES
---------- --------------- ------------ ---------- ---------- -------------- -------------
SRPAGS     MAPSERVICES     13932:53996         172      63887           1495        440563
SRPAGS     MAPSERVICES     467568:47486        231      54138           1363        338529
SRPAGS     MAPSERVICES     470120:47208        288       8620             64        323507