Folks, I need some help in understanding why a job is taking longer when it is run in multiple nodes under RAC versus a single node in RAC and with RAC disabled. I generated trace files with 10046 at level 12 under the following scenarios: 1. two-node RAC 2. one-node RAC 3. Single instance with RAC disabled In each of the above runs the same job was run in the same environment. When I look at the tkprof output, I do not see any significant global cache related waits and that is why I am a little confused that why the job takes longer as we increase the number of nodes. I am pasting a section that is taking the longest amount of time from trace files from each run. 1. TKPROF output from two-node run BEGIN XRX_MAIN_CUST_PROD_PKG.CUST_PROD_MAIN( :errbuf, :rc,:A0); END; call count cpu elapsed disk query current rows ------- ------ -------- ---------- ---------- ---------- ---------- ---------- Parse 1 0.00 0.00 0 0 0 0 Execute 1 523.60 552.10 1318 1213932 415042 1 Fetch 0 0.00 0.00 0 0 0 0 ------- ------ -------- ---------- ---------- ---------- ---------- ---------- total 2 523.60 552.11 1318 1213932 415042 1 Misses in library cache during parse: 1 Optimizer goal: CHOOSE Parsing user id: 173 Elapsed times include waiting on following events: Event waited on Times Max. Wait Total Waited ---------------------------------------- Waited ---------- ------------ SQL*Net message to client 4 0.00 0.00 SQL*Net message from client 4 0.00 0.00 library cache pin 30 0.00 0.04 row cache lock 29 0.00 0.04 rdbms ipc reply 29 0.00 0.03 log file sync 1 0.09 0.09 ************************************************************************ ******** 2. TKPROF from one-node RAC BEGIN XRX_MAIN_CUST_PROD_PKG.CUST_PROD_MAIN( :errbuf, :rc,:A0); END; call count cpu elapsed disk query current rows ------- ------ -------- ---------- ---------- ---------- ---------- ---------- Parse 1 0.00 0.00 0 0 0 0 Execute 1 444.98 450.08 2244 1220178 415182 1 Fetch 0 0.00 0.00 0 0 0 0 ------- ------ -------- ---------- ---------- ---------- ---------- ---------- total 2 444.98 450.08 2244 1220178 415182 1 Misses in library cache during parse: 1 Optimizer goal: CHOOSE Parsing user id: 173 Elapsed times include waiting on following events: Event waited on Times Max. Wait Total Waited ---------------------------------------- Waited ---------- ------------ SQL*Net message to client 4 0.00 0.00 SQL*Net message from client 4 0.00 0.00 log file sync 1 0.00 0.00 ************************************************************************ ******** 3. TKPROF from single-instance with RAC disabled: BEGIN XRX_MAIN_CUST_PROD_PKG.CUST_PROD_MAIN( :errbuf, :rc,:A0); END; call count cpu elapsed disk query current rows ------- ------ -------- ---------- ---------- ---------- ---------- ---------- Parse 1 0.00 0.00 0 0 0 0 Execute 1 460.04 459.60 1170 1208212 415492 1 Fetch 0 0.00 0.00 0 0 0 0 ------- ------ -------- ---------- ---------- ---------- ---------- ---------- total 2 460.04 459.61 1170 1208212 415492 1 Misses in library cache during parse: 0 Optimizer goal: CHOOSE Parsing user id: 173 Elapsed times include waiting on following events: Event waited on Times Max. Wait Total Waited ---------------------------------------- Waited ---------- ------------ SQL*Net message to client 4 0.00 0.00 SQL*Net message from client 4 0.00 0.00 library cache pin 6 0.00 0.00 rdbms ipc reply 6 0.00 0.00 row cache lock 1 0.00 0.00 ************************************************************************ ******** It seems to me that the database CPU usage related to the work done also increases with RAC regardless whether there are any GC related waits or not. Any help would be appreciated. Thanks Amir -- //www.freelists.org/webpage/oracle-l