9.例項活動

Instance Activity Stats for DB: BLISSDB Instance: blissdb Snaps: 4 -5

Statistic Total per Second per Trans
--------------------------------- ------------------ -------------- ------------
CPU used by this session 4,870 4.5 194.8
CPU used when call started 4,870 4.5 194.8
CR blocks created 45 0.0 1.8
DBWR buffers scanned 24,589 22.8 983.6
DBWR checkpoint buffers written 14,013 13.0 560.5
DBWR checkpoints 5 0.0 0.2
……
dirty buffers inspected 38,834 36.0 1,553.4 --髒緩衝的個數
free buffer inspected 40,463 37.5 1,618.5 --如果數量很大,說明緩衝區過小
……

10.I/O

下面兩個報表是面向I/O的。通常，在這裡期望在各裝置上的讀取和寫入操作是均勻分佈的。要找出什麼檔案可能非常“熱”。一旦DBA瞭解瞭如何讀取和寫入這些資料，他們也許能夠透過磁碟間更均勻的分配I/O而得到某些效能提升。

Tablespace IO Stats for DB: BLISSDB Instance: blissdb Snaps: 4 -5
->ordered by IOs (Reads + Writes) desc

Tablespace
------------------------------
Av Av Av Av Buffer Av Buf
Reads Reads/s Rd(ms) Blks/Rd Writes Writes/s Waits Wt(ms)
-------------- ------- ------ ------- ------------ -------- ---------- ------
BLISS_DATA
17,649 16 12.3 1.2 44,134 41 0 0.0
UNDOTBS1
4,484 4 9.6 1.0 29,228 27 0 0.0
SYSTEM
340 0 31.0 1.1 36 0 0 0.0

File IO Stats for DB: BLISSDB Instance: blissdb Snaps: 4 -5
->ordered by Tablespace, File

Tablespace Filename
------------------------ ----------------------------------------------------
Av Av Av Av Buffer Av Buf
Reads Reads/s Rd(ms) Blks/Rd Writes Writes/s Waits Wt(ms)
-------------- ------- ------ ------- ------------ -------- ---------- ------
BLISS_DATA D:ORACLEORADATABLISSDBBLISS01.DBF
5,779 5 12.0 1.2 14,454 13 0
D:ORACLEORADATABLISSDBBLISS02.DBF
5,889 5 12.1 1.2 14,772 14 0
D:ORACLEORADATABLISSDBBLISS03.DBF
5,981 6 12.6 1.2 14,908 14 0

11.緩衝池

Buffer Pool Statistics for DB: BLISSDB Instance: blissdb Snaps: 4 -5
-> Standard block size Pools D: default, K: keep, R: recycle
-> Default Pools for other block sizes: 2k, 4k, 8k, 16k, 32k

Free Write Buffer
Number of Cache Buffer Physical Physical Buffer Complete Busy
P Buffers Hit % Gets Reads Writes Waits Waits Waits
--- ---------- ----- ----------- ----------- ---------- ------- -------- ------
D 3,000 99.4 4,482,816 25,756 73,470 11 9 0
-------------------------------------------------------------

如果我們使用多緩衝池的功能，上面的報表會告訴我們緩衝池引起的使用故障。實際上這只是我們在報表的開頭看到的資訊的重複。

12．回滾段活動

Instance Recovery Stats for DB: BLISSDB Instance: blissdb Snaps: 4 -5
-> B: Begin snapshot, E: End snapshot

Targt Estd Log File Log Ckpt Log Ckpt
MTTR MTTR Recovery Actual Target Size Timeout Interval
(s) (s) Estd IOs Redo Blks Redo Blks Redo Blks Redo Blks Redo Blks
- ----- ----- ---------- ---------- ---------- ---------- ---------- ----------
B 37 17 169 4012 3453 184320 3453
E 37 32 1385 57132 184320 184320 436361
-------------------------------------------------------------
一般期望活動在各回滾段間(除了SYSTEM回滾段外)均勻分佈。在檢查報表的這一部分時，報表標題也具有需要記住的最有用資訊。尤其是，如果完全使用最佳設定時關於Optmal比Avg Active更大的建議。因為這是與DBA最有關的活動(I/O和回滾段資訊)。

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