ORA-12827: insufficient parallel query slaves

Question

Hi All,
We are hitting ORA-12827 after setting up parameters related to parallelism. It was a suggestion from Oracle , just to boost up the performance by setting up auto parallelism and few other parameters complementing to it. We have made changes on 2 Database , but we are hitting this only one database, which has similar in configuration in terms of hardware (32 cpus, gobs of ram , sufficient I/O) but it has less SGA setup (7G) over 30G on other database, which seems fine as if now. Here ,ORA-12827 , clearly suggest that , the server does not have sufficient parallel slaves , may be , already in use by different users. I have a question here , what do you think , what is causing this issue to occur , is it no of users or memory or anything else. I know, parallel stuff is not scalable in terms of no of increased users. Also, since we are on 11GR2, we can go for "parallel statement queuing" and that will not fail us ,because of resources getting exhausted completely, right ? What do you think , would it be a right approach to go with or you would you go different approach? thanks a lot for all of your help in past.
OS -- Enterprise Linux Server release 5.8 (Tikanga)
DB --- 11.2.0.3.0
------------- Parameters suggested by Oracle -----------------------------
change parallel_min_servers=8
change parallel_max_servers=128
change parallel_degree_limit=8
change parallel_degree_policy=AUTO
change parallel_min_percent=50
----------------------------------- Current SGA and Parallel Settings ---------------------
NAME                                 TYPE                              VALUE
fast_start_parallel_rollback         string                            LOW
parallel_adaptive_multi_user         boolean                           TRUE
parallel_automatic_tuning            boolean                           FALSE
parallel_degree_limit                string                            8
parallel_degree_policy               string                            AUTO
parallel_execution_message_size      integer                           16384
parallel_force_local                 boolean                           FALSE
parallel_instance_group              string
parallel_io_cap_enabled              boolean                           FALSE
parallel_max_servers                 integer                           128
parallel_min_percent                 integer                           50
parallel_min_servers                 integer                           8
parallel_min_time_threshold          string                            AUTO
parallel_server                      boolean                           FALSE
parallel_server_instances            integer                           1
parallel_servers_target              integer                           128
parallel_threads_per_cpu             integer                           2
recovery_parallelism                 integer                           0
SQL> show parameter sga_
NAME                                 TYPE                              VALUE
sga_max_size                         big integer                       7G
sga_target                           big integer                       7GRegards

Answer 1

why posted this question then?Fran, it's not about the "ORA-12827" only. I also asked the , what is the reason , one can think of , when comparing other database , which has more memory other then that , pretty much identical. Please go through my question once again , you would realize , what was the question actually.
Regards