Data Guard中MRP无法启动的问题分析和解决-Mysql Tutorial-php.cn

Home

Database

Mysql Tutorial

Data Guard中MRP无法启动的问题分析和解决

WBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWB

Jun 07, 2016 pm 03:53 PM

自己手头有一套dataguard环境，因为也有些日子没有用了，结果突然心血来潮准备启动起来学习一下，突然发现在敲了命令 recover ma

自己手头有一套dataguard环境，因为也有些日子没有用了，，结果突然心血来潮准备启动起来学习一下，突然发现在敲了命令 recover managed standby database disconnect from session之后,命令运行正常,但是后台却报了ora错误。
Sat Jun 27 23:16:39 2015
Recovery Slave PR00 previously exited with exception 1157
Errors in file /u02/dg11g/diag/rdbms/dg11g/DG11G/trace/DG11G_mrp0_6514.trc:
ORA-01157: cannot identify/lock data file 7 - see DBWR trace file
ORA-01110: data file 7: '/u02/dg11g/oradata/DG11G/test_new01.dbf'
MRP0: Background Media Recovery process shutdown (DG11G)
Sat Jun 27 23:16:39 2015
Completed: ALTER DATABASE RECOVER managed standby database disconnect from session
RFS[162]: Opened log for thread 1 sequence 171 dbid 1028247664 branch 880742847
RFS[161]: Opened log for thread 1 sequence 173 dbid 1028247664 branch 880742847
RFS[160]: Opened log for thread 1 sequence 172 dbid 1028247664 branch 880742847
通过上面的日志我们可以看到，MRP进程是在做数据恢复的时候报了ora错误ora-01157
但是RFS还是没有问题，RFS主要是从主库来传输归档文件的，可以看到能够正常从主库中传输归档日志，sequence#号为171,173,172的归档日志都传输到了备库。

本来这个问题没有引起多大的关注，想可能是哪些归档文件没有用到导致的，但是发现MRP压根用不了。所以尽管归档传输完成了，但是数据变更还是应用不到备库。
查看v$archive_gap没有任何记录，说明没有归档日志apply的时候出现问题。

我们来看看这个ora问题的一些明细信息,提示是在7号数据文件的地方报了ora-01157错误。
Errors in file /u02/dg11g/diag/rdbms/dg11g/DG11G/trace/DG11G_mrp0_6514.trc:
ORA-01157: cannot identify/lock data file 7 - see DBWR trace file
ORA-01110: data file 7: '/u02/dg11g/oradata/DG11G/test_new01.dbf'
从官方对于这个问题的描述来看，似乎是数据文件出了问题。
$ oerr ora 01157
01157, 00000, "cannot identify/lock data file %s - see DBWR trace file"
// *Cause: The background process was either unable to find one of the data
// files or failed to lock it because the file was already in use.
// The database will prohibit access to this file but other files will
// be unaffected. However the first instance to open the database will
// need to access all online data files. Accompanying error from the
// operating system describes why the file could not be identified.
// *Action: Have operating system make file available to database. Then either
// open the database or do ALTER SYSTEM CHECK DATAFILES.
因为这个环境被折腾了不知道多少遍，反复切换，反复测试，我都不记得是哪些特殊的操作导致了这个问题了。所以这个问题还得从头来分析。
首先查看了一下/u02/dg11g/oradata/DG11G/test_new01.dbf 这个文件，发现在文件系统中竟然不存在。
但是在数据字典信息中却存在，使用的sql语句为，可以返回对应的记录来。
select name,file# from v$datafile where file#=7;

从这个情况来看，可能是在备库端误删除了这个数据文件造成的。对于删除的数据文件我们怎么来评估呢，首先得查看主库，查看主库中的文件情况,但是在主库中这个数据文件和表空间压根不存在。
这样一来这个问题就有些棘手了。
如果能够修复MRP的问题，看似这个问题就引刃而解，如果修复不了，可能这个dataguard就不可用了，可能得考虑重建一个物理备库了。
对此我们采取保守态度，带着一丝尝试看看备库能不能启动到open read only状态。
但是这三个操作的结果让我有些迷茫了。
open不了，说可能需要恢复，恢复的文件竟然是system01.dbf，尝试recover until cancel也未果。
idle> alter database open read only;
alter database open read only
*
ERROR at line 1:
ORA-10458: standby database requires recovery
ORA-01196: file 1 is inconsistent due to a failed media recovery session
ORA-01110: data file 1: '/u02/dg11g/oradata/DG11G/system01.dbf'

idle> recover database until cancel;
ORA-00283: recovery session canceled due to errors
ORA-01610: recovery using the BACKUP CONTROLFILE option must be done

idle> alter database open read only;
alter database open read only
*
ERROR at line 1:
ORA-10458: standby database requires recovery
ORA-01196: file 1 is inconsistent due to a failed media recovery session
ORA-01110: data file 1: '/u02/dg11g/oradata/DG11G/system01.dbf'

对于这个问题，如果有一个sql语句能够一针见血的解决问题就好了，自己在反复尝试之后发现还是有的，问题的解决思路就是先解决ORA-01157问题，然后dataguard中的MRP问题就能引刃而解。
对于ora-01157这个问题中的数据文件在主库中不存在，但是在备库的数据字典中存在，我们可以直接在备库中把数据字典中的问题先解决了。
idle> alter database datafile '/u02/dg11g/oradata/DG11G/test_new01.dbf' offline drop;
Database altered.
然后dataguard的日志中就出现而来转机，在后台会去校验这个文件的问题，只是抛出了一个警告。Warning: Datafile 7 (/u02/ora11g/oradata/TEST11G/test_new01.dbf) is offline during full database recovery and will not be recovered
然后MRP就正常启动了。后台开始使用归档文件做数据恢复了。

Statement

The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn

Explain the role of InnoDB redo logs and undo logs.Apr 15, 2025 am 12:16 AM

InnoDB uses redologs and undologs to ensure data consistency and reliability. 1.redologs record data page modification to ensure crash recovery and transaction persistence. 2.undologs records the original data value and supports transaction rollback and MVCC.

What are the key metrics to look for in an EXPLAIN output (type, key, rows, Extra)?Apr 15, 2025 am 12:15 AM

Key metrics for EXPLAIN commands include type, key, rows, and Extra. 1) The type reflects the access type of the query. The higher the value, the higher the efficiency, such as const is better than ALL. 2) The key displays the index used, and NULL indicates no index. 3) rows estimates the number of scanned rows, affecting query performance. 4) Extra provides additional information, such as Usingfilesort prompts that it needs to be optimized.

What is the Using temporary status in EXPLAIN and how to avoid it?Apr 15, 2025 am 12:14 AM

Usingtemporary indicates that the need to create temporary tables in MySQL queries, which are commonly found in ORDERBY using DISTINCT, GROUPBY, or non-indexed columns. You can avoid the occurrence of indexes and rewrite queries and improve query performance. Specifically, when Usingtemporary appears in EXPLAIN output, it means that MySQL needs to create temporary tables to handle queries. This usually occurs when: 1) deduplication or grouping when using DISTINCT or GROUPBY; 2) sort when ORDERBY contains non-index columns; 3) use complex subquery or join operations. Optimization methods include: 1) ORDERBY and GROUPB

Describe the different SQL transaction isolation levels (Read Uncommitted, Read Committed, Repeatable Read, Serializable) and their implications in MySQL/InnoDB.Apr 15, 2025 am 12:11 AM

MySQL/InnoDB supports four transaction isolation levels: ReadUncommitted, ReadCommitted, RepeatableRead and Serializable. 1.ReadUncommitted allows reading of uncommitted data, which may cause dirty reading. 2. ReadCommitted avoids dirty reading, but non-repeatable reading may occur. 3.RepeatableRead is the default level, avoiding dirty reading and non-repeatable reading, but phantom reading may occur. 4. Serializable avoids all concurrency problems but reduces concurrency. Choosing the appropriate isolation level requires balancing data consistency and performance requirements.

MySQL vs. Other Databases: Comparing the OptionsApr 15, 2025 am 12:08 AM

MySQL is suitable for web applications and content management systems and is popular for its open source, high performance and ease of use. 1) Compared with PostgreSQL, MySQL performs better in simple queries and high concurrent read operations. 2) Compared with Oracle, MySQL is more popular among small and medium-sized enterprises because of its open source and low cost. 3) Compared with Microsoft SQL Server, MySQL is more suitable for cross-platform applications. 4) Unlike MongoDB, MySQL is more suitable for structured data and transaction processing.

How does MySQL index cardinality affect query performance?Apr 14, 2025 am 12:18 AM

MySQL index cardinality has a significant impact on query performance: 1. High cardinality index can more effectively narrow the data range and improve query efficiency; 2. Low cardinality index may lead to full table scanning and reduce query performance; 3. In joint index, high cardinality sequences should be placed in front to optimize query.

MySQL: Resources and Tutorials for New UsersApr 14, 2025 am 12:16 AM

The MySQL learning path includes basic knowledge, core concepts, usage examples, and optimization techniques. 1) Understand basic concepts such as tables, rows, columns, and SQL queries. 2) Learn the definition, working principles and advantages of MySQL. 3) Master basic CRUD operations and advanced usage, such as indexes and stored procedures. 4) Familiar with common error debugging and performance optimization suggestions, such as rational use of indexes and optimization queries. Through these steps, you will have a full grasp of the use and optimization of MySQL.

Real-World MySQL: Examples and Use CasesApr 14, 2025 am 12:15 AM

MySQL's real-world applications include basic database design and complex query optimization. 1) Basic usage: used to store and manage user data, such as inserting, querying, updating and deleting user information. 2) Advanced usage: Handle complex business logic, such as order and inventory management of e-commerce platforms. 3) Performance optimization: Improve performance by rationally using indexes, partition tables and query caches.

See all articles