"gc buffer busy" wait Cause ?

From: VIVEK_SHARMA <VIVEK_SHARMA_at_infosys.com>
Date: Wed, 14 Mar 2007 20:55:57 +0530
Message-ID: <BBD944BCAC3AB4499DFBAFB1D8AF302002B9E5D0@BLRKECMSG11.ad.infosys.com>

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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Received on Wed Mar 14 2007 - 10:25:57 CDT