Oracle 連接失敗問題
1，給安徽的同事安裝了一個生產Oracle數據庫，最近一段時間 總是在2點-10點之間出現數據庫連不上的情況，具體tomcat應用日誌如下：
08:58:09 ERROR c.d.web.controller.DBAppController - 查詢更新版本請求異常org.springframework.dao.DataAccessResourceFailureException:
### Error querying database. Cause: java.sql.SQLException: Io exception: Connection timed out
### The error may exist in file [/usr/local/tomcat/xx/WEB-INF/classes/mapper/DBAppMapper.xml]
### The error may involve com.dabay.web.dao.DBAppDao.selectProperties-Inline
### The error occurred while setting parameters
### SQL: SELECT KEY,VALUE,DESCRIPTION FROM APP_PROPERTIES WHERE KEY=? AND DATA_STATUS!=‘9‘
### Cause: java.sql.SQLException: Io exception: Connection timed out
; SQL []; Io exception: Connection timed out; nested exception is java.sql.SQLException: Io exception: Connection timed out
08:58:09 ERROR c.d.web.controller.DBAppController - DGW_0922084243406:查詢輪播圖請求異常org.springframework.dao.DataAccessResourceFailureException:
### Error querying database. Cause: java.sql.SQLException: Io exception: Connection timed out
### The error may exist in file [/usr/local/tomcat/xx/WEB-INF/classes/mapper/DBAppMapper.xml]
### The error may involve defaultParameterMap
### The error occurred while setting parameters
### SQL: SELECT TITLE, URL, REMARKS, PNGURL FROM INFO_BANNER WHERE DATA_STATUS!=‘9‘ AND ROWNUM<6 ORDER BY ORDERDESC asc,CREATE_TIME desc
### Cause: java.sql.SQLException: Io exception: Connection timed out
; SQL []; Io exception: Connection timed out; nested exception is java.sql.SQLException: Io exception: Connection timed out
2，想到排查ORACLE數據庫是否正常，百度到了如下三個結果
一：查看數據庫監聽是否啟動
lsnrctl status
二：查看數據庫運行狀態，是否open
select instance_name,status from v$instance;
三：查看alert日誌,查看是否有錯誤信息
SQL> show parameter background_dump
NAME TYPE
------------------------------------ ----------------------
VALUE
------------------------------
background_dump_dest string
/u01/app/oracle/diag/rdbms/just_test/test/trace
是的，有alert日誌，接下來查看alert日誌，如下
db_recovery_file_dest_size of 3882 MB is 45.88% used. This is a
user-specified limit on the amount of space that will be used by this
database for recovery-related files, and does not reflect the amount of
space available in the underlying filesystem or ASM diskgroup.
Fri Sep 22 02:01:05 2017
Starting background process CJQ0
Fri Sep 22 02:01:05 2017
CJQ0 started with pid=22, OS id=6797
Fri Sep 22 02:06:05 2017
Starting background process SMCO
Fri Sep 22 02:06:05 2017
SMCO started with pid=32, OS id=7393
Fri Sep 22 04:21:10 2017
Thread 1 cannot allocate new log, sequence 221
Private strand flush not complete
Current log# 1 seq# 220 mem# 0: /u01/app/oracle/oradata/hsrs_pro/redo01.log
Thread 1 advanced to log sequence 221 (LGWR switch)
Current log# 2 seq# 221 mem# 0: /u01/app/oracle/oradata/hsrs_pro/redo02.log
Fri Sep 22 09:00:35 2017
先看到了 Thread 1 cannot allocate new log, sequence 221,於是又百度了一下，找到了如下結果
（摘自 http://blog.csdn.net/zonelan/article/details/7613519）
這個實際上是個比較常見的錯誤。通常來說是因為在日誌被寫滿時會切換 日誌組，這個時候會觸發一次checkpoint，DBWR會把內存中的臟塊往數據文件中寫，只要沒寫結束就不會釋放這個日誌組。如果歸檔模式被開啟的 話，還會伴隨著ARCH寫歸檔的過程。如果redo log產生的過快，當CPK或歸檔還沒完成，LGWR已經把其余的日誌組寫滿，又要往當前的日誌組裏面寫redo log的時候，這個時候就會發生沖突，數據庫就會被掛起。並且一直會往alert.log中寫類似上面的錯誤信息。
於是有了以下的操作：
SQL> select group#,sequence#,bytes,members,status from v$log; #查看每組日誌的狀態
GROUP# SEQUENCE# BYTES MEMBERS STATUS
---------- ---------- ---------- ---------- --------------------------------
1 220 52428800 1 INACTIVE ##空閑的
2 221 52428800 1 CURRENT ##當前的
3 219 52428800 1 INACTIVE ##空閑的
SQL> alter database add logfile group 4 (‘/u01/app/oracle/oradata/xx/redo04.log‘) size 500M; 增加日誌組
Database altered.
SQL> alter database add logfile group 5 (‘/u01/app/oracle/oradata/xx/redo05.log‘) size 500M;
Database altered.
SQL> alter system switch logfile; 切換日誌組SQL> select group#,sequence#,bytes,members,status from v$log; #查看狀態發現有了區別
GROUP# SEQUENCE# BYTES MEMBERS STATUS
---------- ---------- ---------- ---------- --------------------------------
1 22052428800 1 INACTIVE
2 22152428800 1 ACTIVE
3 21952428800 1 INACTIVE
4 222 524288000 1 ACTIVE
5 223 524288000 1 CURRENT
經理過如上操作，突然看到了alert日誌中有一個recovery 並且 tomcat應用日誌中也有recovery這個單詞，於是又百度了一番。分別執行了如下命令（不懂什麽意思）
SQL> select * from v$flash_recovery_area_usage;
SQL> select * from v$recovery_file_dest; 查看recovery的實際大小：
NAME
--------------------------------------------------------------------------------
SPACE_LIMIT SPACE_USED SPACE_RECLAIMABLE NUMBER_OF_FILES
----------- ---------- ----------------- ---------------
/u01/app/oracle/recovery_area
4070572032 3926630400 2059067392 41
SQL> select * from v$flash_recovery_area_usage
2 ;
FILE_TYPE PERCENT_SPACE_USED
---------------------------------------- ------------------
PERCENT_SPACE_RECLAIMABLE NUMBER_OF_FILES
------------------------- ---------------
CONTROL FILE 0
00
REDO LOG 0
00
ARCHIVED LOG 0
00
FILE_TYPE PERCENT_SPACE_USED
---------------------------------------- ------------------
PERCENT_SPACE_RECLAIMABLE NUMBER_OF_FILES
------------------------- ---------------
BACKUP PIECE 53.96
50.58 37
IMAGE COPY 42.5
04
FLASHBACK LOG 0
00
FILE_TYPE PERCENT_SPACE_USED
---------------------------------------- ------------------
PERCENT_SPACE_RECLAIMABLE NUMBER_OF_FILES
------------------------- ---------------
FOREIGN ARCHIVED LOG 0
00
7 rows selected.
SQL> show parameter db_recovery_file_dest_size; 最後發現這個才是我要找的 查看當前recovery的限制大小
NAME TYPE
------------------------------------ ----------------------
VALUE
------------------------------
db_recovery_file_dest_size big integer
3882M
SQL> alter system set db_recovery_file_dest_size=5882M scope=spfile; 改大一點？
System altered.
SQL> show parameter db_recovery_file_dest_size; 但是好像並沒有用，還是這麽大
NAME TYPE
------------------------------------ ----------------------
VALUE
------------------------------
db_recovery_file_dest_size big integer
3882M
好吧，仍然百度：）執行了如下命令好像管用了
SQL> alter system set db_recovery_file_dest_size=10G;
System altered.
SQL> show parameter db_recovery_file_dest_size;
NAME TYPE
------------------------------------ ----------------------
VALUE
------------------------------
db_recovery_file_dest_size big integer
10G先觀察看看吧~應用日誌10點好像沒有超時報錯了~~ 完
補充一下，下面這倆貨的區別
scope=both
scope=spfile
Oracle spfile就是動態參數文件，裏面設置了Oracle 的各種參數。所謂的動態，
就是說你可以在不關閉數據庫的情況下，更改數據庫參數，記錄在spfile裏面。更改參數
的時候，有4種scope選項，scope就是範圍。
scope=spfile 僅僅更改spfile裏面的記載，不更改內存，也就是不立即生效，而是等
下次數據庫啟動生效。
有一些參數只允許用這種方法更改，scope=memory 僅僅更改內存，不改spfile。也就是下次
啟動就失效了
scope=both 內存和spfile都更改，不指定scope參數，等同於scope=both。本文出自 “隨風” 博客，請務必保留此出處http://358778493.blog.51cto.com/11386071/1967685
Oracle 連接失敗問題