2012-05-21

  今天在检查oracle alert日志的时候发现这样一个提示：

 

Beginning log switch checkpoint up to RBA [0xdc63.2.10], SCN: 0x0000.877b8625
Thread 1 advanced to log sequence 56419
  Current log# 5 seq# 56419 mem# 0: /u01/oraprod/proddata/log05a.dbf
  Current log# 5 seq# 56419 mem# 1: /u01/oraprod/proddata/log05b.dbf
Fri Aug 28 16:18:57 2009
ARC1: Evaluating archive   log 4 thread 1 sequence 56418
ARC1: Beginning to archive log 4 thread 1 sequence 56418
Creating archive destination LOG_ARCHIVE_DEST_1: '/install/prod_archivelog/1_56418.dbf'
Fri Aug 28 16:19:08 2009
Completed checkpoint up to RBA [0xdc63.2.10], SCN: 0x0000.877b8625
Fri Aug 28 16:19:32 2009
Beginning log switch checkpoint up to RBA [0xdc64.2.10], SCN: 0x0000.877bf9bb
Thread 1 advanced to log sequence 56420
  Current log# 6 seq# 56420 mem# 0: /u01/oraprod/proddata/log06a.dbf
  Current log# 6 seq# 56420 mem# 1: /u01/oraprod/proddata/log06b.dbf
Fri Aug 28 16:19:32 2009
ARC0: Evaluating archive   log 4 thread 1 sequence 56418
ARC0: Unable to archive log 4 thread 1 sequence 56418
      Log actively being archived by another process
ARC0: Evaluating archive   log 5 thread 1 sequence 56419
ARC0: Beginning to archive log 5 thread 1 sequence 56419
Creating archive destination LOG_ARCHIVE_DEST_1: '/install/prod_archivelog/1_56419.dbf'
Fri Aug 28 16:19:34 2009
ARC1: Completed archiving  log 4 thread 1 sequence 56418
ARC1: Evaluating archive   log 5 thread 1 sequence 56419
ARC1: Unable to archive log 5 thread 1 sequence 56419
      Log actively being archived by another process
ARC1: Evaluating archive   log 5 thread 1 sequence 56419
ARC1: Unable to archive log 5 thread 1 sequence 56419
      Log actively being archived by another process
Fri Aug 28 16:19:45 2009
Completed checkpoint up to RBA [0xdc64.2.10], SCN: 0x0000.877bf9bb
Fri Aug 28 16:20:05 2009
Beginning log switch checkpoint up to RBA [0xdc65.2.10], SCN: 0x0000.877c6ab7
Thread 1 advanced to log sequence 56421
  Current log# 3 seq# 56421 mem# 0: /u01/oraprod/proddata/log03a.dbf
  Current log# 3 seq# 56421 mem# 1: /u01/oraprod/proddata/log03b.dbf
Fri Aug 28 16:20:05 2009
ARC1: Evaluating archive   log 5 thread 1 sequence 56419
ARC1: Unable to archive log 5 thread 1 sequence 56419
      Log actively being archived by another process
ARC1: Evaluating archive   log 6 thread 1 sequence 56420
ARC1: Beginning to archive log 6 thread 1 sequence 56420
Creating archive destination LOG_ARCHIVE_DEST_1: '/install/prod_archivelog/1_56420.dbf'
Fri Aug 28 16:20:08 2009
ARC0: Completed archiving  log 5 thread 1 sequence 56419
ARC0: Evaluating archive   log 6 thread 1 sequence 56420
ARC0: Unable to archive log 6 thread 1 sequence 56420
      Log actively being archived by another process
Fri Aug 28 16:20:14 2009
Completed checkpoint up to RBA [0xdc65.2.10], SCN: 0x0000.877c6ab7
Fri Aug 28 16:20:32 2009
ARC1: Completed archiving  log 6 thread 1 sequence 56420
Fri Aug 28 16:20:49 2009
Beginning log switch checkpoint up to RBA [0xdc66.2.10], SCN: 0x0000.877cceab
Thread 1 advanced to log sequence 56422
  Current log# 4 seq# 56422 mem# 0: /u01/oraprod/proddata/log04a.dbf
  Current log# 4 seq# 56422 mem# 1: /u01/oraprod/proddata/log04b.dbf
Fri Aug 28 16:20:49 2009
ARC0: Evaluating archive   log 3 thread 1 sequence 56421
ARC0: Beginning to archive log 3 thread 1 sequence 56421
Creating archive destination LOG_ARCHIVE_DEST_1: '/install/prod_archivelog/1_56421.dbf'
Fri Aug 28 16:21:02 2009
Completed checkpoint up to RBA [0xdc66.2.10], SCN: 0x0000.877cceab

 

检查了一下数据库的归档进程数：

 

SQL> show parameter archive_max_process;

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
log_archive_max_processes            integer     2

 

两个archive进程出现了相互竞争的现象。这说明了日志的产生量很大，两个归档进程都同时在工作。如果其中一个正在归档某个日志，而另一个进程来尝试归档该日志的话，则会出现这个提示。虽然不是什么错误但提醒我I/O的问题要引起注意了。到网上查了一下资料出现这种可能的还有在RMAN备份的情况下（rman执行backup加选项plus archivelog 的时候）。另外还有一种可能就是：某个归档进程出现异常或者归档目的地有问题造成归档进程阻塞而没有及时完成。eygle在他的blog里提到即使你的归档进程是1竞争也是存在的（）