"gc buffer busy" wait Cause ?

Folks



Qs What is the Cause of "gc buffer busy" wait? Is it always due to a DML
i.e. "INSERT / UPDATE" or can it be due to a "SELECT" too?



NOTE - IDX_LOGIN_TABLE (on session_id), IDX_LOGIN_VAL_ITEMS_ (on
session_id), indexes belong to Tables which maintain unique session
information of each logged in Application User.



Qs Are dedicated server processes on the Different RAC nodes attempting
to "concurrently" do DML on the SAME BLOCK/ROW of the Respective Table &
hence index?



Will share Statspack, as needed.



Cheers



Config info:-

Oracle ver RAC 10gR2

Solaris 10

Veritas CFS 5.0

Tran. Nature OLTP

Application Banking



Top 5 Timed Events
Avg %Total

~~~~~~~~~~~~~~~~~~
wait   Call

Event                                            Waits    Time (s)
(ms)   Time

----------------------------------------- ------------ -----------
------ ------

CPU time                                                     2,552
49.1

gc buffer busy                                  30,938       2,043
66   39.3

gc cr block 2-way                              135,826         132
1    2.5

gc current block 2-way                         148,931         127
1    2.5

log file sync                                   29,922          53
2    1.0

          -------------------------------------------------------------



Segments by Global Cache Buffer Busy Waits  DB/Inst: PNBRAC/PNBRAC1
Snaps: 301-

-> There is no specific Threshold for Segment GC Buffer Busy Waits



                                                                 GC
Buffer

                                           Subobject    Obj.
Busy   Pct

Owner      Tablespace Object Name          Name         Type
Waits Total

---------- ---------- -------------------- ------------ -----
------------ -----

TBAADM     IDX_B2K_TE IDX_LOGIN_TABLE                   INDEX
24,255  53.3

TBAADM     IDX_B2K_TE IDX_LOGIN_VAL_ITEMS_              INDEX
16,406  36.1

TBAADM     TRANS      INW_CLG_ZONE_HDR_TAB              TABLE
1,850   4.1

TBAADM     ICP_TBLSPC INW_CLG_PART_TRAN_TA ICP_PART1    TABLE
909   2.0

TBAADM     PART_TAB_I INW_CLG_INST_TABLE   ICI_PART1    TABLE
769   1.7

          -------------------------------------------------------------





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