记一次Oracle DG备库实例宕分析-编程知识

记一次Oracle DG备库实例宕分析

一、问题现象

同事反馈国外点在国内的XXX备库实例宕，尝试将该实例重启，结果重启报如下错误，未能正常启动该数据库。

Standby crash recovery failed to bring standby database to a consistent
point because needed redo hasn't arrived yet.
MRP: Wait timeout: thread 1 sequence# 0
Errors with log +DG/xxxx/archivelog/2021_12_29/thread_2_seq_24193.3766.1092589235
Standby Crash Recovery aborted due to error 16016.
Errors in file /u01/app/oracle/diag/rdbms/xxxx/xxxx/trace/xxxx_ora_67164.trc:
ORA-16016: archived log for thread 1 sequence# 22789 unavailable
Recovery interrupted!
Some recovered datafiles maybe left media fuzzy
Media recovery may continue but open resetlogs may fail
Completed Standby Crash Recovery.
Errors in file /u01/app/oracle/diag/rdbms/xxxx/xxxx/trace/xxxx_ora_67164.trc:
ORA-10458: standby database requires recovery
ORA-01196: file 1 is inconsistent due to a failed media recovery session
ORA-01110: data file 1: '+DG/xxxx/datafile/system.419.941189591'
ORA-10458 signalled during: ALTER DATABASE OPEN...

帮同事看了下问题，经过多次尝试，最终将数据库重新open，并正常接收主库传来的日志，数据库同步正常。

二、问题分析

问题看似解决了，其实只是做了一半，就是为什么这个实例会宕，另外就是这个数据库之前也配置了告警，为什么本次没有发出告警，要分析下原因，避免下次再重新改情况。

该数据库是国外点在国内的一个备库，和主库实时同步，数据库版本是Oracle 11.2.0.4 ,该数据库服务器上共部署了两个实例，而本次是只宕了其中一个实例，另一个实例正常。

首先查看了下问题发生时段的alert日志，在日志里看到了在数据库发生故障时所报的日志信息：

Errors in file /u01/app/oracle/diag/rdbms/xxxx/xxxx/trace/xxxx_lgwr_45171.trc:
ORA-04021: timeout occurred while waiting to lock object
LGWR (ospid: 45171): terminating the instance due to error 4021
Wed Dec 29 17:20:02 2021
System state dump requested by (instance=1, osid=45171 (LGWR)), summary=[abnormal instance termination].
System State dumped to trace file /u01/app/oracle/diag/rdbms/xxxx/xxxx/trace/xxxx_diag_45155_20211229172002.trc
Dumping diagnostic data in directory=[cdmp_20211229172002], requested by (instance=1, osid=45171 (LGWR)), summary=[abnormal instance termination].
Wed Dec 29 17:20:02 2021
ORA-1092 : opitsk aborting process
Wed Dec 29 17:20:02 2021
License high water mark = 49
Instance terminated by LGWR, pid = 45171
USER (ospid: 159932): terminating the instance
Instance terminated by USER, pid = 159932
Wed Dec 29 17:20:04 2021
Adjusting the default value of parameter parallel_max_servers
from 1280 to 970 due to the value of parameter processes (1000)
Starting ORACLE instance (normal)
************************ Large Pages Information *******************
Per process system memlock (soft) limit = 143 GBTotal Shared Global Region in Large Pages = 14 GB (75%)Large Pages used by this instance: 7329 (14 GB)
Large Pages unused system wide = 6 (12 MB)
Large Pages configured system wide = 17000 (33 GB)
Large Page size = 2048 KB

从日志里可以看到由于产生了ORA-1092 : opitsk aborting process报错，导致该数据库实例宕。此时就要去分析是什么原因导致产生ORA-1092报错。首先看了下报错时产生的/u01/app/oracle/diag/rdbms/xxxx/xxxx/trace/xxxx_diag_45155_20211229172002.trc文件，文件内容太多，格式化输出后也不太好排查，希望能从其它地方获取到一些价值信息。

首先在MOS上查询了 ORA-1092 : opitsk aborting process报错原因，MOS上讲该问题产生的原因也比较多，此时尝试看下操作系统日志，看下是否有什么价值的信息。

从操作系统的 /var/log/messages里，发现日志不停的有xxx-xxx-standby-db1 kernel: EXT4-fs warning (device sda2): ext4_dx_add_entry: Directory index full!这样的报错：

该报错的原因是因为操作系统小文件太多，导致innode块被占用完了，然后查了下数据库相关文件，发现是两个数据库的审计文件占用了大量innode，通过du -sh 查看都被夯住了，是否是该问题导致数据库实例宕呢。